Developmental defects, Nevi & benignDevelopmental defects, Nevi & benign
epithelial tumorsepithelial tumors
Dr Mesfin Hune...
 Developmental defects are errors in morphogenesis.Developmental defects are errors in morphogenesis.
 They largely aris...
1-Malformations1-Malformations:: are primary anatomical defectsare primary anatomical defects
that occur during the develo...
2-Deformations2-Deformations reflect abnormal moulding of thereflect abnormal moulding of the
growing fetus by intrauterin...
3-Disruptions3-Disruptions:: Occur when the fetus is subject to aOccur when the fetus is subject to a
destructive intraute...
• A chimeraA chimera is an individual formed from two differentis an individual formed from two different
zygotes.zygotes....
• MosaicismMosaicism is a term that denotes the presence of twois a term that denotes the presence of two
or more genetica...
 Mosaicism most commonly appears to arise from post-Mosaicism most commonly appears to arise from post-
zygotic chromosom...
 Congenital malformations may be caused by genetic orCongenital malformations may be caused by genetic or
environmental f...
Environmental factors provoking congenitalEnvironmental factors provoking congenital
malformations (i.e. teratogens) inclu...
Classification of benign epithelial tumors basedClassification of benign epithelial tumors based
on histologyon histology
Classification….Classification….
ClassificationClassification ……
NEVUS:NEVUS:
 A nevus, or mole, is a benign proliferation of normalA nevus, or mole, is a benign proliferation of normal
...
NEVUS…NEVUS…
 It has been proposed that the definition should includeIt has been proposed that the definition should incl...
Classification of naeviClassification of naevi According to Rook)According to Rook)
I-Epidermal naeviI-Epidermal naevi
1...
II-Dermal and subcutaneous naevi -II-Dermal and subcutaneous naevi -
1- Connective tissue naevi1- Connective tissue naevi
...
BENIGN EPITHELIAL TUMORSBENIGN EPITHELIAL TUMORS (Classification according to FITZPATRIK):(Classification according to FIT...
2- Epidermal nevi2- Epidermal nevi
Linear verrucous epidermal nevusLinear verrucous epidermal nevus
- Localized,- Localize...
3- Clear cell acanthoma3- Clear cell acanthoma
4- Warty dyskeratoma4- Warty dyskeratoma
5- Acanthoma fissuratum5- Acanthom...
6- Cysts of epithelial origin6- Cysts of epithelial origin
- Epidermoid cyst- Epidermoid cyst
- Trichilemmal cyst- Trichil...
Nevi…Nevi…
I-Epidermal NevusI-Epidermal Nevus
 Epidermal nevus is a developmental (hamartomatous)Epidermal nevus is a dev...
Epidemiology:Epidemiology:
 The incidence:1 per 1000 live births.The incidence:1 per 1000 live births.
 The majority occ...
Classification of Epidermal NeviClassification of Epidermal Nevi
Classification…Classification…
 Verrucus epidermalVerrucus epidermal
nevus:nevus:
- Localized,- Localized,
-Systematized,...
1.1-Verrucous Epidermal Nevus1.1-Verrucous Epidermal Nevus
Synonyms:linear verrucous epidermal nevus, linear epidermal nev...
 An epidermal nevus with diffuse or extensiveAn epidermal nevus with diffuse or extensive
distribution is calleddistribut...
 Inflammatory linear verrucous epidermalInflammatory linear verrucous epidermal
nevusnevus ((ILVENILVEN),), is an inflamm...
ILVENILVEN
Extensive epidermal nevusExtensive epidermal nevus
Epidermal nevusEpidermal nevus
LVENLVEN
Epidermal nevusEpidermal nevus
Epidermal nevusEpidermal nevus
Epidermal nevusEpidermal nevus
Epidermal nevusEpidermal nevus
NB: Linear psoriasisNB: Linear psoriasis
Linear LPLinear LP
Course and complicationsCourse and complications
 A verrucous epidermal nevus may enlarge slowly during childhood.A verru...
Course…Course…
 Rarely, BCC & SCC have been reported to develop in aRarely, BCC & SCC have been reported to develop in a
...
PathologyPathology
 There is hyperkeratosis, acanthosis, & papillomatosis.There is hyperkeratosis, acanthosis, & papillom...
Differential diagnosis:Differential diagnosis:
Verrucous epidermal nevi should be differentiated fromVerrucous epidermal n...
 Linear porokeratosis is distinguished by itsLinear porokeratosis is distinguished by its
pathognomonic cornoid lamellae....
 Lichen striatus may be difficult to exclude clinically andLichen striatus may be difficult to exclude clinically and
his...
TreatmentTreatment
 Excision is the most reliable treatment.Excision is the most reliable treatment.
 However, this may ...
 Topical treatment include:Topical treatment include:
podophyllin,retinoic acid,anthralin,alpha-hydroxy acidspodophyllin,...
1.2-1.2-Nevus SebaceousNevus Sebaceous
Synonym:Synonym: nevus sebaceous of Jadassohn.nevus sebaceous of Jadassohn.
Clinica...
 The well-developed lesion with its characteristic yellowThe well-developed lesion with its characteristic yellow
or yell...
Course and complicationsCourse and complications
 Nevus sebaceous appears to be under some hormonalNevus sebaceous appear...
 It is believed that nevus sebaceous arises fromIt is believed that nevus sebaceous arises from
pleuripotential primary e...
 Less common associations include sebaceousLess common associations include sebaceous
epithelioma, hidradenoma, syringoma...
Syringocystadenoma papilliferumSyringocystadenoma papilliferum
PathologyPathology
The epidermis shows papillomatous hyperplasia. In theThe epidermis shows papillomatous hyperplasia. In ...
Differential diagnosisDifferential diagnosis
 In a well-developed lesion, nevus sebaceous is easy toIn a well-developed l...
TreatmentTreatment
 Surgical excision of a nevus sebaceous is recommendedSurgical excision of a nevus sebaceous is recomm...
1.3-Nevus comedonicus1.3-Nevus comedonicus
1.4-Becker's Nevus1.4-Becker's Nevus
Syn.:Syn.:Becker's pigmented hairy nevus,Becker's melanosis.Becker's pigmented hairy ...
Becker's…Becker's…
Clinical features:Clinical features:
 It appears to be more common in men.It appears to be more common...
 Becker's nevus is sharply demarcated hyperpigmentedBecker's nevus is sharply demarcated hyperpigmented
patch that is cha...
 Occasionally, Becker's nevus may appear onOccasionally, Becker's nevus may appear on atypicalatypical
sitessites such as...
 Several months to years after the appearance of pigmentation,Several months to years after the appearance of pigmentatio...
Pathophysiology:Pathophysiology:
• The pathogenesis of Becker nevus remains uncertain.The pathogenesis of Becker nevus rem...
Course and complicationsCourse and complications
 A Becker's nevus may enlarge slowly for a year or twoA Becker's nevus m...
 Rarely, Becker's nevus may be associatedRarely, Becker's nevus may be associated
with hypoplasia of underlying structure...
Other associations seen with Becker nevus include:Other associations seen with Becker nevus include:
 Unilateral or ipsil...
 Becker nevus is considered a benign process; however, anBecker nevus is considered a benign process; however, an
associa...
PathologyPathology
 The epidermis shows slight acanthosis and papillomatosis.The epidermis shows slight acanthosis and pa...
Differential diagnosisDifferential diagnosis
 A congenital Becker's nevus may be confused with aA congenital Becker's nev...
TreatmentTreatment
 Because a Becker's nevus does not have any malignantBecause a Becker's nevus does not have any malign...
Nevus SpilusNevus Spilus
 Nevus spilus is a congenital, isolated benign lesionNevus spilus is a congenital, isolated beni...
 Histologic studies of the background CALM show aHistologic studies of the background CALM show a
slight increase in the ...
 The relationship of nevus spilus to NF is unresolved.The relationship of nevus spilus to NF is unresolved.
 Nevus spilu...
Seborrheic KeratosisSeborrheic Keratosis
 Synonyms: senile wart, senile keratosis, seborrheicSynonyms: senile wart, senil...
Classification of benign epithelial tumorsClassification of benign epithelial tumors
 They are very common & most people will develop atThey are very common & most people will develop at
least one such tumo...
 Seborrheic keratoses typically begin as flat, sharplySeborrheic keratoses typically begin as flat, sharply
demarcated, b...
 Seborrheic keratoses typically have a “stuck-on”Seborrheic keratoses typically have a “stuck-on”
appearance secondary to...
 A clinical variant of the typical seborrheicA clinical variant of the typical seborrheic
keratosis described is a varian...
 They show a surface morphology similar to that of theThey show a surface morphology similar to that of the
classic sebor...
 Lesions around the neck can catch on clothing, as canLesions around the neck can catch on clothing, as can
lesions aroun...
EtiologyEtiology
 The etiology of seborrheic keratoses is not known.The etiology of seborrheic keratoses is not known.
 ...
 B/c of the verrucous appearance of, HPV is suggestedB/c of the verrucous appearance of, HPV is suggested
as a possible c...
 The eruptive appearance of multiple seborrheicThe eruptive appearance of multiple seborrheic
keratoses (keratoses (the s...
Clinicopathologic Variants:Clinicopathologic Variants:
1-Common Seborrheic Keratosis1-Common Seborrheic Keratosis
Synonyms...
 Keratin cysts are often prominent and may be follicularKeratin cysts are often prominent and may be follicular
or extraf...
2-Reticulated Seborrheic Keratosis2-Reticulated Seborrheic Keratosis
Synonym:Synonym: adenoid seborrheic keratosis.adenoid...
3-Clonal Seborrheic Keratosis3-Clonal Seborrheic Keratosis
 Nests, usually but not always well defined, of round,Nests, u...
4-Stucco Keratosis4-Stucco Keratosis
Synonyms: hyperkeratotic seborrheic keratosis,acanthoticSynonyms: hyperkeratotic sebo...
5-Irritated Seborrheic Keratosis5-Irritated Seborrheic Keratosis
• Synonyms:Synonyms: inflamed seborrheic keratosis,inflam...
 These resemble poorly differentiated keratin pearls inThese resemble poorly differentiated keratin pearls in
squamous ce...
6-Seborrheic Keratosis with Squamous Atypia6-Seborrheic Keratosis with Squamous Atypia
 Cellular atypia and dyskeratosis ...
7-Melanoacanthoma7-Melanoacanthoma
Synonym:Synonym: pigmented seborrheic keratosis.pigmented seborrheic keratosis.
 Melan...
8-Dermatosis Papulosa Nigra8-Dermatosis Papulosa Nigra
 These small facial papules, originally described inThese small fa...
Skin Cancer AssociationsSkin Cancer Associations
• BCC and other common skin cancers have beenBCC and other common skin ca...
The Sign of Leser-TrelatThe Sign of Leser-Trelat
 Multiple eruptive seborrheic keratoses, also known asMultiple eruptive ...
 A hallmark of many patients with so-called eruptiveA hallmark of many patients with so-called eruptive
seborrheic kerato...
 It is common clinical experience to see an increase inIt is common clinical experience to see an increase in
the promine...
TreatmentTreatment
• Lesions that are bothering the patient functionally orLesions that are bothering the patient function...
 Laser therapy using a pigmented lesion laser such asLaser therapy using a pigmented lesion laser such as
the Q-switched ...
 Surgical excision is also effective but is usually not theSurgical excision is also effective but is usually not the
tre...
Disorders of MelanocytesDisorders of Melanocytes
ACQUIRED MELANOCYTIC NEVOCELLULAR NEVIACQUIRED MELANOCYTIC NEVOCELLULAR NEVI
 Melanocytic nevocellular nevi are small (<1...
EpidemiologyEpidemiology
 One of the most common acquired new growths in CaucasiansOne of the most common acquired new gr...
HistoryHistory
 Duration of LesionsDuration of Lesions These lesions, which are commonlyThese lesions, which are commonly...
Skin SymptomsSkin Symptoms
 Nevocellular nevi are asymptomatic, and if a lesion persistentlyNevocellular nevi are asympto...
Classification:Classification:
1-Junctional Melanocytic NCN1-Junctional Melanocytic NCN
 Cells at the dermal-epidermal ju...
3.3. Dermal melanocytic NCNDermal melanocytic NCN::
These represent the last stage of the evolution of NCN.These represent...
Evolution:Evolution:
 Melanocytic NCN develop during childhood and usually haveMelanocytic NCN develop during childhood a...
 Since common melanocytic NCN lose their capacity forSince common melanocytic NCN lose their capacity for
melanization, t...
I-Junctional Melanocytic Nevocellular NeviI-Junctional Melanocytic Nevocellular Nevi
Skin Lesions:Skin Lesions: Macule, or...
Junctional NMNJunctional NMN
II-Compound Melanocytic Nevocellular NeviII-Compound Melanocytic Nevocellular Nevi
 Compound melanocytic nevocellular nev...
Skin Lesions:Skin Lesions: Papules or nodules.Papules or nodules.
 COLORCOLOR Dark brown, sometimes even black; color may...
Differential DiagnosisDifferential Diagnosis
 Tan/Brown/Black Papule :Tan/Brown/Black Papule :
 Seborrheic keratosis,Seb...
Compound NMNCompound NMN
III-Dermal Melanocytic Nevocellular NeviIII-Dermal Melanocytic Nevocellular Nevi
Skin Lesions:Skin Lesions: Papule or Nodu...
Differential Diagnosis:Differential Diagnosis:
Skin-Colored PapuleSkin-Colored Papule
 Basal cell carcinoma,Basal cell ca...
HALO NEVOMELANOCYTIC NEVUSHALO NEVOMELANOCYTIC NEVUS
 This lesion is a nevomelanocytic nevus that is encircled by aThis l...
Epidemiology and EtiologyEpidemiology and Etiology
 AgeAge First three decades,First three decades,
 Race and SexRace an...
HistoryHistory
Three StagesThree Stages
1-Development (in months) of halo around preexisting nevus cell1-Development (in m...
Physical Examination:Physical Examination:
Skin Lesions: -Skin Lesions: - Papular brown nevus (5.0mm) with halo,Papular br...
Differential DiagnosisDifferential Diagnosis
 ““Halo” Depigmentation around Other LesionsHalo” Depigmentation around Othe...
PathophysiologyPathophysiology
 Immunologic phenomena are responsible for the dynamicImmunologic phenomena are responsibl...
CourseCourse
 The lesions undergo spontaneous resolution.The lesions undergo spontaneous resolution.
 Nevus cell nevi wi...
BLUE NEVUS:BLUE NEVUS:
 A blue nevus is an acquired, benign, firm, dark-blue to gray-to-A blue nevus is an acquired, beni...
Epidemiology:Epidemiology:
 AgeAge Onset in late adolescence,Onset in late adolescence,
 SexSex Equal distribution,Equal...
Physical ExaminationPhysical Examination
Skin LesionsSkin Lesions Papules to nodules usually <10.0 mm in diameter.Papules ...
Differential DiagnosisDifferential Diagnosis
Blue/Gray Papule:Blue/Gray Papule:
 Dermatofibroma,Dermatofibroma,
 Glomus ...
DermatopathologyDermatopathology
 Melanin-containing fibroblast-like dermal melanocytes groupedMelanin-containing fibrobl...
PathogenesisPathogenesis
 Probably represents ectopic accumulations of melanin-Probably represents ectopic accumulations ...
ManagementManagement
 Blue nevi smaller than 10.0 mm in diameter and stable forBlue nevi smaller than 10.0 mm in diameter...
SPITZ NEVUSSPITZ NEVUS
 Spitz nevus is a benign, dome-shaped, hairless, smallSpitz nevus is a benign, dome-shaped, hairle...
EpidemiologyEpidemiology
 IncidenceIncidence 1.4 : 100,000 (Australia)1.4 : 100,000 (Australia)
 Age:Age:
 Occurs at al...
Physical ExaminationPhysical Examination
 Skin LesionsSkin Lesions Papule or nodule, smooth-topped, hairless.Papule or no...
Spitz nevusSpitz nevus
Nevus spilusNevus spilus
Spitz nevusSpitz nevus
Differential DiagnosisDifferential Diagnosis
 Pink or Tan PapulePink or Tan Papule Pigmented spindle cell nevus ofPigment...
DermatopathologyDermatopathology
LIGHT MICROSCOPYLIGHT MICROSCOPY
 SiteSite Reticular dermis and epidermisReticular dermi...
DiagnosisDiagnosis
 Although the clinical appearance and recent growthAlthough the clinical appearance and recent growth
...
SignificanceSignificance
 Excision in its entirety is important because the condition recursExcision in its entirety is i...
Course and PrognosisCourse and Prognosis
 Spitz tumors probably do not involute, as do common acquiredSpitz tumors probab...
Congenital neviCongenital nevi
 Congenital nevi are present at birth & resultCongenital nevi are present at birth & resul...
Pathophysiology:Pathophysiology:
 The etiology of congenital melanocytic nevi remains unclear.The etiology of congenital ...
Stratified into 3 groups according to size:Stratified into 3 groups according to size:
1-Small nevi are less than 1.5 cm i...
Giant nevi are often surrounded by several smaller satellite nevi.Giant nevi are often surrounded by several smaller satel...
The current diagnostic criteria forThe current diagnostic criteria for
neurocutaneous melanosis are:neurocutaneous melano...
 Neurocutaneous melanosis may result from an error in theNeurocutaneous melanosis may result from an error in the
morphog...
Frequency:Frequency:
Internationally:Internationally: present in 1-2% of newborn infants.present in 1-2% of newborn infant...
Mortality/Morbidity:Mortality/Morbidity:
 For giant congenital melanocytic nevi, the risk ofFor giant congenital melanocy...
DDx:DDx:
 Becker nevusBecker nevus
 Spitz nevus,Spitz nevus,
 Seborrheic keratosis,Seborrheic keratosis,
 Pagets disea...
Ageminated nevusAgeminated nevus
Nevomelanocytic neviNevomelanocytic nevi
Etiology and PathogenesisEtiology and Pathogenesis
 Congenital and acquired nevo...
Course and PrognosisCourse and Prognosis
 By definition, CNN appear at birth, but varieties of CNNBy definition, CNN appe...
Congenital nevomelanocytic neviCongenital nevomelanocytic nevi
Congenital nevomelanocytic neviCongenital nevomelanocytic nevi
Very Large (“Giant”) CNNVery Large (“Giant”) CNN
 Giant CNN of the head and neck may beGiant CNN of the head and neck may be
associated with involvement of theassociated ...
 Differential DiagnosisDifferential Diagnosis
 Common acquired nevomelanocytic nevi, dysplasticCommon acquired nevomelan...
BirthmarksBirthmarks
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
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Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
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Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
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Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
Developmental defects, nevi & benign epithelial tumors
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Developmental defects, nevi & benign epithelial tumors

  1. 1. Developmental defects, Nevi & benignDevelopmental defects, Nevi & benign epithelial tumorsepithelial tumors Dr Mesfin Hunegnaw,Dr Mesfin Hunegnaw, Consultant dermatologist andConsultant dermatologist and venerologist, AAU, Medicalvenerologist, AAU, Medical faculty, Dept. offaculty, Dept. of DermatovenerologyDermatovenerology
  2. 2.  Developmental defects are errors in morphogenesis.Developmental defects are errors in morphogenesis.  They largely arise during intrauterine life; most areThey largely arise during intrauterine life; most are congenital, i.e. present at birth.congenital, i.e. present at birth.  The term embraces malformations, deformations andThe term embraces malformations, deformations and disruptions.disruptions.
  3. 3. 1-Malformations1-Malformations:: are primary anatomical defectsare primary anatomical defects that occur during the development of an organ orthat occur during the development of an organ or tissue.tissue.  Such malformations are most commonly single, orSuch malformations are most commonly single, or isolated, usually occurring in normal children, orisolated, usually occurring in normal children, or multiple, affecting several body systems.multiple, affecting several body systems.  When multiple malformations occur in a recognizableWhen multiple malformations occur in a recognizable pattern, they constitute apattern, they constitute a multiple malformationmultiple malformation syndromesyndrome, and are the frequently accompanied by, and are the frequently accompanied by mental retardation.mental retardation.
  4. 4. 2-Deformations2-Deformations reflect abnormal moulding of thereflect abnormal moulding of the growing fetus by intrauterine mechanical forces.growing fetus by intrauterine mechanical forces.  Deformations are most commonly musculoskeletal,Deformations are most commonly musculoskeletal, and generally affect fetuses with neuromuscularand generally affect fetuses with neuromuscular problems.problems.  For example, paralysis in fetuses with spina bifidaFor example, paralysis in fetuses with spina bifida characteristically results in positional deformation ofcharacteristically results in positional deformation of the legs and feet.the legs and feet.  Oligohydramnios, whatever the cause, may result in aOligohydramnios, whatever the cause, may result in a characteristic combination of congenital abnormalities,characteristic combination of congenital abnormalities, usually referred to as Potter's syndrome.usually referred to as Potter's syndrome.
  5. 5. 3-Disruptions3-Disruptions:: Occur when the fetus is subject to aOccur when the fetus is subject to a destructive intrauterine influence, such as infection,destructive intrauterine influence, such as infection, circulatory compromise or amniotic bands.circulatory compromise or amniotic bands.  There is clearly considerable overlap between theseThere is clearly considerable overlap between these three categories.three categories.
  6. 6. • A chimeraA chimera is an individual formed from two differentis an individual formed from two different zygotes.zygotes. • Chimeras can result from the fertilization of an ovumChimeras can result from the fertilization of an ovum containing a polar body by two spermatozoa, or fromcontaining a polar body by two spermatozoa, or from the fusion of dizygotic twin embryos.the fusion of dizygotic twin embryos.
  7. 7. • MosaicismMosaicism is a term that denotes the presence of twois a term that denotes the presence of two or more genetically distinct cell populations in anor more genetically distinct cell populations in an individual derived from a single zygote.individual derived from a single zygote. • The differences can be between single genes, groups ofThe differences can be between single genes, groups of genes or entire chromosomes.genes or entire chromosomes.
  8. 8.  Mosaicism most commonly appears to arise from post-Mosaicism most commonly appears to arise from post- zygotic chromosomal non-dysjunction during mitosis orzygotic chromosomal non-dysjunction during mitosis or somatic mutation during embryogenesis.somatic mutation during embryogenesis.  A number of patients with cutaneous pigmentaryA number of patients with cutaneous pigmentary abnormalities reflecting mosaicism are now beingabnormalities reflecting mosaicism are now being reported.reported.
  9. 9.  Congenital malformations may be caused by genetic orCongenital malformations may be caused by genetic or environmental factors, or combinations of the two,environmental factors, or combinations of the two, although, in practice, the aetiology is often obscure.although, in practice, the aetiology is often obscure.  Skin lesions that occur in the linear configurationsSkin lesions that occur in the linear configurations originally described by Blaschko appear to reflectoriginally described by Blaschko appear to reflect genetic mosaicism.genetic mosaicism.
  10. 10. Environmental factors provoking congenitalEnvironmental factors provoking congenital malformations (i.e. teratogens) include:-malformations (i.e. teratogens) include:-  Intrauterine infections,Intrauterine infections,  Ionizing radiation,Ionizing radiation,  Drugs taken during pregnancy: sp. anti-cancer agents…Drugs taken during pregnancy: sp. anti-cancer agents…  Alcohol abuse during pregnancy,Alcohol abuse during pregnancy,  Trace metal excesses or deficiency during pregnancy,Trace metal excesses or deficiency during pregnancy, particularly mercury exposure, Zn def.particularly mercury exposure, Zn def.  Maternal diseases, such as DM and phenylketonuria.Maternal diseases, such as DM and phenylketonuria.
  11. 11. Classification of benign epithelial tumors basedClassification of benign epithelial tumors based on histologyon histology
  12. 12. Classification….Classification….
  13. 13. ClassificationClassification ……
  14. 14. NEVUS:NEVUS:  A nevus, or mole, is a benign proliferation of normalA nevus, or mole, is a benign proliferation of normal skin constituents.skin constituents.  Melanocytic nevus is a benign proliferation ofMelanocytic nevus is a benign proliferation of melanocytes or melanocytic nevus cells that appears inmelanocytes or melanocytic nevus cells that appears in childhood.childhood.  The number of nevi peaks in early adulthood andThe number of nevi peaks in early adulthood and decreases thereafter.decreases thereafter.  Indicate circumscribed lesions of the skin and/orIndicate circumscribed lesions of the skin and/or neighbouring mucosae, which are permanent or at leastneighbouring mucosae, which are permanent or at least very long-lasting, & which are not neoplastic.very long-lasting, & which are not neoplastic.
  15. 15. NEVUS…NEVUS…  It has been proposed that the definition should includeIt has been proposed that the definition should include a requirement that lesions must be caused by genetica requirement that lesions must be caused by genetic mosaism.mosaism.  Lesions resembling naevi but not fulfilling all the criteriaLesions resembling naevi but not fulfilling all the criteria should be called naevoid.should be called naevoid.  Naevi are classified according to whether they ariseNaevi are classified according to whether they arise from epidermal or dermal structures, andfrom epidermal or dermal structures, and  In the second, according to the presumed organ ofIn the second, according to the presumed organ of origin or to the predominant cell type.origin or to the predominant cell type.
  16. 16. Classification of naeviClassification of naevi According to Rook)According to Rook) I-Epidermal naeviI-Epidermal naevi 1- Keratinocyte naevi1- Keratinocyte naevi Verrucous epidermal naevusVerrucous epidermal naevus Linear porokeratosisLinear porokeratosis Inflammatory epidermal naeviInflammatory epidermal naevi 2- Follicular naevi2- Follicular naevi Hairy malformation of palms & solesHairy malformation of palms & soles 3- Eccrine naevi3- Eccrine naevi Eccrine naeviEccrine naevi Pure eccrine naevusPure eccrine naevus Eccrine angiomatous hamartomaEccrine angiomatous hamartoma 4- Becekers nevus4- Becekers nevus
  17. 17. II-Dermal and subcutaneous naevi -II-Dermal and subcutaneous naevi - 1- Connective tissue naevi1- Connective tissue naevi - Collagen nevi: Familial cutaneous collagenoma, TSC…- Collagen nevi: Familial cutaneous collagenoma, TSC… - Elastic naevi- Elastic naevi 2- Smooth-muscle naevi2- Smooth-muscle naevi - Comedo naevus- Comedo naevus - Congenital smooth-muscle hamartoma- Congenital smooth-muscle hamartoma - Linear basal cell naevus- Linear basal cell naevus - Diffuse smooth-muscle hamartoma- Diffuse smooth-muscle hamartoma 3-Vascular naevi3-Vascular naevi - Haemangiomas- Haemangiomas - Verrucus haemangioma- Verrucus haemangioma - Hamartoma- Hamartoma - Vascular (capillary) malformations- Vascular (capillary) malformations - Port wine’s stain- Port wine’s stain 4- Fat nevi4- Fat nevi:: Congenital lipoma, Fibrolipoma…Congenital lipoma, Fibrolipoma…
  18. 18. BENIGN EPITHELIAL TUMORSBENIGN EPITHELIAL TUMORS (Classification according to FITZPATRIK):(Classification according to FITZPATRIK): 1-Seborrheic keratosis1-Seborrheic keratosis • Common seborrheic keratosis,Common seborrheic keratosis, • Reticulated seborrheic keratosis,Reticulated seborrheic keratosis, • Stucco keratosis,Stucco keratosis, • Clonal seborrheic keratosis,Clonal seborrheic keratosis, • Irritated seborrheic keratosis,Irritated seborrheic keratosis, • Seborrheic keratosis with squamous atypia,Seborrheic keratosis with squamous atypia, • Melanoacanthoma (pigmented seborrheic keratosis),Melanoacanthoma (pigmented seborrheic keratosis), • Dermatosis papulosa nigra,Dermatosis papulosa nigra, • Sign of Leser-Trelat,Sign of Leser-Trelat,
  19. 19. 2- Epidermal nevi2- Epidermal nevi Linear verrucous epidermal nevusLinear verrucous epidermal nevus - Localized,- Localized, - Systematized,- Systematized, Nevus unius lateris,Nevus unius lateris, Ichthyosis hystrix,Ichthyosis hystrix, Inflammatory linear verrucous epidermal nevus (ILVEN),Inflammatory linear verrucous epidermal nevus (ILVEN), Nevus sebaceous of Jadassohn,Nevus sebaceous of Jadassohn, Nevus comedonicus,Nevus comedonicus, Eccrine nevus,Eccrine nevus, Apocrine nevus,Apocrine nevus, Becker's nevus,Becker's nevus, White sponge nevus,White sponge nevus, Epidermal nevus syndrome.Epidermal nevus syndrome.
  20. 20. 3- Clear cell acanthoma3- Clear cell acanthoma 4- Warty dyskeratoma4- Warty dyskeratoma 5- Acanthoma fissuratum5- Acanthoma fissuratum
  21. 21. 6- Cysts of epithelial origin6- Cysts of epithelial origin - Epidermoid cyst- Epidermoid cyst - Trichilemmal cyst- Trichilemmal cyst - Milium- Milium - Steatocystoma multiplex- Steatocystoma multiplex - Dermoid cyst- Dermoid cyst - Branchial cyst- Branchial cyst - Preauricular cyst and sinus- Preauricular cyst and sinus
  22. 22. Nevi…Nevi… I-Epidermal NevusI-Epidermal Nevus  Epidermal nevus is a developmental (hamartomatous)Epidermal nevus is a developmental (hamartomatous) disorder xcd by hyperplasia of epidermal structuresdisorder xcd by hyperplasia of epidermal structures (surface epidermis and adnexal structures) in a(surface epidermis and adnexal structures) in a circumscribed area of the skin.circumscribed area of the skin.  The term nevus is used here to denote aThe term nevus is used here to denote a developmental defect;developmental defect;  There is no proliferation of nevocellular nevus cellsThere is no proliferation of nevocellular nevus cells (melanocytes) in the lesion.(melanocytes) in the lesion.
  23. 23. Epidemiology:Epidemiology:  The incidence:1 per 1000 live births.The incidence:1 per 1000 live births.  The majority occur sporadically; familial cases have beenThe majority occur sporadically; familial cases have been described.described.  Sex: equal.Sex: equal.  Most epidermal nevi are present at birth or infancy, rarely lesionsMost epidermal nevi are present at birth or infancy, rarely lesions appear as late as puberty.appear as late as puberty.  Over 80 % of the cases have onset of their epidermal nevi in theOver 80 % of the cases have onset of their epidermal nevi in the first year of life;first year of life;  The remainder develop b/n the ages 1 & 7 years.The remainder develop b/n the ages 1 & 7 years.  Late-developing lesions probably represent lesions that haveLate-developing lesions probably represent lesions that have always been present, but new inspection of recent growth resultedalways been present, but new inspection of recent growth resulted in their recognition.in their recognition.  Everyone has at least one nevus.Everyone has at least one nevus.
  24. 24. Classification of Epidermal NeviClassification of Epidermal Nevi
  25. 25. Classification…Classification…  Verrucus epidermalVerrucus epidermal nevus:nevus: - Localized,- Localized, -Systematized,-Systematized,  Nevus unis lateralis,Nevus unis lateralis,  Ichthyosis hysterix,Ichthyosis hysterix,  ILVEN.ILVEN.  Nevus sebaceus,Nevus sebaceus,  Eccrine nevus,Eccrine nevus,  Apocrine nevus,Apocrine nevus,  Nevus comedonicus,Nevus comedonicus,  Becker's nevus,Becker's nevus,  Spongiform nevusSpongiform nevus
  26. 26. 1.1-Verrucous Epidermal Nevus1.1-Verrucous Epidermal Nevus Synonyms:linear verrucous epidermal nevus, linear epidermal nevus.Synonyms:linear verrucous epidermal nevus, linear epidermal nevus. Clinical featuresClinical features  The lesion consists of closely set verrucous papules that mayThe lesion consists of closely set verrucous papules that may coalesce to form well-demarcated papillomatous plaques.coalesce to form well-demarcated papillomatous plaques.  It may be skin-colored, brown, or gray-brown.It may be skin-colored, brown, or gray-brown.  A linear configuration is common, sp. limb lesions.A linear configuration is common, sp. limb lesions.  Such lesions may appear to follow skin tension lines, or Blaschko'sSuch lesions may appear to follow skin tension lines, or Blaschko's lines.lines.  Verrucous epidermal nevi may be localized or diffuse.Verrucous epidermal nevi may be localized or diffuse.
  27. 27.  An epidermal nevus with diffuse or extensiveAn epidermal nevus with diffuse or extensive distribution is calleddistribution is called systematized epidermal nevus.systematized epidermal nevus.  When the lesions are distributed on one-half of theWhen the lesions are distributed on one-half of the body, it is termedbody, it is termed nevus unius laterisnevus unius lateris..  Ichthyosis hystrixIchthyosis hystrix refers to an epidermal nevusrefers to an epidermal nevus with extensive bilateral distributionwith extensive bilateral distribution..  In these systematized nevi, the lesions on the limbs areIn these systematized nevi, the lesions on the limbs are usually linear in configuration,usually linear in configuration,  Those on trunk tend to form wavy, transverse bands.Those on trunk tend to form wavy, transverse bands.
  28. 28.  Inflammatory linear verrucous epidermalInflammatory linear verrucous epidermal nevusnevus ((ILVENILVEN),), is an inflammatory variant ofis an inflammatory variant of epidermal nevus.epidermal nevus.  The lesion is pruritic and clinically showsThe lesion is pruritic and clinically shows erythema, scaling, and crusting.erythema, scaling, and crusting.
  29. 29. ILVENILVEN
  30. 30. Extensive epidermal nevusExtensive epidermal nevus
  31. 31. Epidermal nevusEpidermal nevus
  32. 32. LVENLVEN
  33. 33. Epidermal nevusEpidermal nevus
  34. 34. Epidermal nevusEpidermal nevus
  35. 35. Epidermal nevusEpidermal nevus
  36. 36. Epidermal nevusEpidermal nevus
  37. 37. NB: Linear psoriasisNB: Linear psoriasis
  38. 38. Linear LPLinear LP
  39. 39. Course and complicationsCourse and complications  A verrucous epidermal nevus may enlarge slowly during childhood.A verrucous epidermal nevus may enlarge slowly during childhood.  By adolescence, the lesion usually reaches a stable size andBy adolescence, the lesion usually reaches a stable size and further extension is unlikely.further extension is unlikely.  In Rogers' series of 131 cases, only 16 % of the epidermal neviIn Rogers' series of 131 cases, only 16 % of the epidermal nevi present at birth showed extension, compared with 65 % of lesionspresent at birth showed extension, compared with 65 % of lesions of later onset; extension rarely lasts for more than 2 years.of later onset; extension rarely lasts for more than 2 years.  Epidermal nevus, especially if extensive, may be associated withEpidermal nevus, especially if extensive, may be associated with developmental abnormalities in other systemsdevelopmental abnormalities in other systems (“Epidermal(“Epidermal Nevus Syndrome”).Nevus Syndrome”).
  40. 40. Course…Course…  Rarely, BCC & SCC have been reported to develop in aRarely, BCC & SCC have been reported to develop in a verrucous epidermal nevus;verrucous epidermal nevus;  This malignant transformation should be suspectedThis malignant transformation should be suspected when sudden localized growth, nodules, or ulcerswhen sudden localized growth, nodules, or ulcers appear.appear.  Epidermal nevi in intertriginous areas may becomeEpidermal nevi in intertriginous areas may become macerated and secondarily infected.macerated and secondarily infected.
  41. 41. PathologyPathology  There is hyperkeratosis, acanthosis, & papillomatosis.There is hyperkeratosis, acanthosis, & papillomatosis.  The rete ridges are elongated. The histologic picture is essentiallyThe rete ridges are elongated. The histologic picture is essentially that of a benign papilloma.that of a benign papilloma.  Epidermolytic hyperkeratosis may be seen.Epidermolytic hyperkeratosis may be seen. This is characterized by compact hyperkeratosis, vacuolization ofThis is characterized by compact hyperkeratosis, vacuolization of the upper and middle prickle cell layer, and large keratohyalinethe upper and middle prickle cell layer, and large keratohyaline granules within or outside the cells.granules within or outside the cells.  Epidermolytic hyperkeratosis is most frequently seen in ichthyosisEpidermolytic hyperkeratosis is most frequently seen in ichthyosis hystrix but may also be found in localized epidermal nevi.hystrix but may also be found in localized epidermal nevi.  The ILVEN lesion shows a dermal chronic inflammatory infiltrate inThe ILVEN lesion shows a dermal chronic inflammatory infiltrate in the dermis in addition to above findings.the dermis in addition to above findings.  Furthermore, the characteristic feature of alternatingFurthermore, the characteristic feature of alternating areas of hyperkeratosis with a thickened granular layer andareas of hyperkeratosis with a thickened granular layer and parakeratosis without a granular area may be present.parakeratosis without a granular area may be present.
  42. 42. Differential diagnosis:Differential diagnosis: Verrucous epidermal nevi should be differentiated fromVerrucous epidermal nevi should be differentiated from other linear hyperkeratotic or verrucous lesions:other linear hyperkeratotic or verrucous lesions:  Incontinentia pigmenti (verrucous stage),Incontinentia pigmenti (verrucous stage),  Lichen striatus,Lichen striatus,  Linear porokeratosis,Linear porokeratosis,  Linear lichen planus,andLinear lichen planus,and  Linear psoriasis.Linear psoriasis. The latter two conditions are considered by someThe latter two conditions are considered by some authors as lichenoid & psoriasiform variants ofauthors as lichenoid & psoriasiform variants of linear epidermal nevus.linear epidermal nevus.
  43. 43.  Linear porokeratosis is distinguished by itsLinear porokeratosis is distinguished by its pathognomonic cornoid lamellae.pathognomonic cornoid lamellae.  The history of an antecedent vesicular stage and theThe history of an antecedent vesicular stage and the transient nature of the linear verrucous lesions oftransient nature of the linear verrucous lesions of incontinentia pigmenti allow differentiation of thisincontinentia pigmenti allow differentiation of this condition from an epidermal nevus;condition from an epidermal nevus;  Histologically, incontinentia pigmenti showsHistologically, incontinentia pigmenti shows eosinophilic exocytosis, dyskeratosis, basal layereosinophilic exocytosis, dyskeratosis, basal layer vacuolization, and pigment incontinence that arevacuolization, and pigment incontinence that are absent in an epidermal nevus.absent in an epidermal nevus.
  44. 44.  Lichen striatus may be difficult to exclude clinically andLichen striatus may be difficult to exclude clinically and histologically fromhistologically from ILVENILVEN..  Their differentiation is important from a prognosticTheir differentiation is important from a prognostic point of view as lichen striatus is self-limited, whereaspoint of view as lichen striatus is self-limited, whereas ILVEN persist indefinitely.ILVEN persist indefinitely.  Clinically, lichen striatus is asymptomatic, whereasClinically, lichen striatus is asymptomatic, whereas ILVEN is usually pruritic;ILVEN is usually pruritic;  Histologically,lichen striatus shows little or noHistologically,lichen striatus shows little or no acanthosis & may have lichenoid inflammatoryacanthosis & may have lichenoid inflammatory infiltrateinfiltrate..
  45. 45. TreatmentTreatment  Excision is the most reliable treatment.Excision is the most reliable treatment.  However, this may not be practical or advisable if the epidermalHowever, this may not be practical or advisable if the epidermal nevus is very extensive or at sites not amenable to simplenevus is very extensive or at sites not amenable to simple surgery.surgery.  The excision should extend to the deep dermis; otherwise theThe excision should extend to the deep dermis; otherwise the lesion may recur.lesion may recur.  Alternative treatments include:Alternative treatments include: laser, Cryotherapy,laser, Cryotherapy, electrofulguration, dermabrasion, or chemical peels withelectrofulguration, dermabrasion, or chemical peels with trichloroacetic acid or phenol.trichloroacetic acid or phenol.  These treatment modalities usually remove only the superficialThese treatment modalities usually remove only the superficial portion of the nevus and recurrence is common.portion of the nevus and recurrence is common.
  46. 46.  Topical treatment include:Topical treatment include: podophyllin,retinoic acid,anthralin,alpha-hydroxy acidspodophyllin,retinoic acid,anthralin,alpha-hydroxy acids and is relatively ineffective.and is relatively ineffective.  Systemic retinoids can produce a partial but usuallySystemic retinoids can produce a partial but usually temporary response in some patients with extensivetemporary response in some patients with extensive disease.disease.  Since epidermal nevus is associated with a small risk ofSince epidermal nevus is associated with a small risk of malignancy, suspect areas of any lesion should bemalignancy, suspect areas of any lesion should be biopsied.biopsied.  If malignancy is confirmed, the entire lesion should beIf malignancy is confirmed, the entire lesion should be excised if possible.excised if possible.
  47. 47. 1.2-1.2-Nevus SebaceousNevus Sebaceous Synonym:Synonym: nevus sebaceous of Jadassohn.nevus sebaceous of Jadassohn. Clinical featuresClinical features  This usually presents as a solitary lesion at birth or inThis usually presents as a solitary lesion at birth or in early childhood.early childhood.  There is a predilection for the scalp, where it manifestsThere is a predilection for the scalp, where it manifests as a patch or slightly elevated yellowish plaque withas a patch or slightly elevated yellowish plaque with alopecia.alopecia.  Less commonly, nevus sebaceous may be found on theLess commonly, nevus sebaceous may be found on the face, neck, or trunk.face, neck, or trunk.  Nevus sebaceous occurring exclusively in the oral cavityNevus sebaceous occurring exclusively in the oral cavity has also been reported.has also been reported.
  48. 48.  The well-developed lesion with its characteristic yellowThe well-developed lesion with its characteristic yellow or yellow-brown color, linear configuration, andor yellow-brown color, linear configuration, and verrucous surface is quite distinctive.verrucous surface is quite distinctive.  However, in early childhood, the lesion may be flat andHowever, in early childhood, the lesion may be flat and inconspicuous; the characteristic appearance may notinconspicuous; the characteristic appearance may not develop until puberty.develop until puberty.  Nevus sebaceous occurs sporadically; familial nevusNevus sebaceous occurs sporadically; familial nevus sebaceous has been described but is exceedingly rare.sebaceous has been described but is exceedingly rare.
  49. 49. Course and complicationsCourse and complications  Nevus sebaceous appears to be under some hormonalNevus sebaceous appears to be under some hormonal control.control.  The lesion can be raised at birth, flatten in childhood,The lesion can be raised at birth, flatten in childhood, and become raised again during puberty.and become raised again during puberty.  Further extension after puberty is uncommon.Further extension after puberty is uncommon.  Systemic abnormalities may occur in association with aSystemic abnormalities may occur in association with a nevus sebaceous (“Epidermal Nevus Syndrome,”).nevus sebaceous (“Epidermal Nevus Syndrome,”).  This is more common in patients with multiple orThis is more common in patients with multiple or extensive lesions.extensive lesions.  Another significant complication is the development ofAnother significant complication is the development of secondary tumors that may be benign or malignant.secondary tumors that may be benign or malignant.
  50. 50.  It is believed that nevus sebaceous arises fromIt is believed that nevus sebaceous arises from pleuripotential primary epithelial germ cells and thatpleuripotential primary epithelial germ cells and that these cells have the capacity to dedifferentiate intothese cells have the capacity to dedifferentiate into various epithelial tumors, of which the most frequentvarious epithelial tumors, of which the most frequent are syringocystadenoma papilliferum (8 to 19 %) andare syringocystadenoma papilliferum (8 to 19 %) and BCC (5 to 7 %).BCC (5 to 7 %).
  51. 51.  Less common associations include sebaceousLess common associations include sebaceous epithelioma, hidradenoma, syringoma, chondroidepithelioma, hidradenoma, syringoma, chondroid syringoma, trichilemmoma, desmoplasticsyringoma, trichilemmoma, desmoplastic trichilemmoma, proliferating trichilemmal tumor, andtrichilemmoma, proliferating trichilemmal tumor, and metaplastic synovial cysts.metaplastic synovial cysts.  The development of squamous cell carcinoma, apocrineThe development of squamous cell carcinoma, apocrine carcinoma, and malignant eccrine poroma has beencarcinoma, and malignant eccrine poroma has been reported but is rare.reported but is rare.
  52. 52. Syringocystadenoma papilliferumSyringocystadenoma papilliferum
  53. 53. PathologyPathology The epidermis shows papillomatous hyperplasia. In theThe epidermis shows papillomatous hyperplasia. In the dermis, there are increased numbers of maturedermis, there are increased numbers of mature sebaceous glands.sebaceous glands. Apocrine glands are often found in the deep dermis.Apocrine glands are often found in the deep dermis. Frequently, small hair follicles and buds of basaloid cellsFrequently, small hair follicles and buds of basaloid cells that may represent malformed hair germs are present.that may represent malformed hair germs are present. In childhood, the sebaceous glands in nevus sebaceousIn childhood, the sebaceous glands in nevus sebaceous areare underdeveloped and the histologic finding may consistunderdeveloped and the histologic finding may consist of only immature hair structures.of only immature hair structures.
  54. 54. Differential diagnosisDifferential diagnosis  In a well-developed lesion, nevus sebaceous is easy toIn a well-developed lesion, nevus sebaceous is easy to diagnose and should not be confused with otherdiagnose and should not be confused with other conditions.conditions.  Although some authors make a distinction between anAlthough some authors make a distinction between an epidermal nevus with a predominant sebaceousepidermal nevus with a predominant sebaceous component and a nevus sebaceous, this may well be acomponent and a nevus sebaceous, this may well be a matter of semantics.matter of semantics.  In childhood, when the lesion may not be wellIn childhood, when the lesion may not be well developed, the differential diagnosis should includedeveloped, the differential diagnosis should include other congenital causes of localized alopecia, such asother congenital causes of localized alopecia, such as aplasia cutis and congenital triangular alopecia.aplasia cutis and congenital triangular alopecia.
  55. 55. TreatmentTreatment  Surgical excision of a nevus sebaceous is recommendedSurgical excision of a nevus sebaceous is recommended because of the high potential for development of basalbecause of the high potential for development of basal cell carcinoma and other tumors.cell carcinoma and other tumors.  The lesion should preferably be excised before pubertyThe lesion should preferably be excised before puberty because it may enlarge and the risk of malignancybecause it may enlarge and the risk of malignancy increases after puberty.increases after puberty.
  56. 56. 1.3-Nevus comedonicus1.3-Nevus comedonicus
  57. 57. 1.4-Becker's Nevus1.4-Becker's Nevus Syn.:Syn.:Becker's pigmented hairy nevus,Becker's melanosis.Becker's pigmented hairy nevus,Becker's melanosis. First described by Becker in 1949, this lesion is fairlyFirst described by Becker in 1949, this lesion is fairly common and is found in all races.common and is found in all races.
  58. 58. Becker's…Becker's… Clinical features:Clinical features:  It appears to be more common in men.It appears to be more common in men.  Prevalence of 0.52 % in men.Prevalence of 0.52 % in men.  The lesion may be present at birth or may develop inThe lesion may be present at birth or may develop in early childhood, but the majority of cases are firstearly childhood, but the majority of cases are first noticed shortly before, at, or after puberty.noticed shortly before, at, or after puberty.  Familial cases have been described.Familial cases have been described.
  59. 59.  Becker's nevus is sharply demarcated hyperpigmentedBecker's nevus is sharply demarcated hyperpigmented patch that is characteristically situated over thepatch that is characteristically situated over the shoulder, anterior chest, or scapula.shoulder, anterior chest, or scapula.  Typically, coarse dark hairs are seen within the lesion,Typically, coarse dark hairs are seen within the lesion, but this may not be evident in early lesions or in fair-but this may not be evident in early lesions or in fair- complexioned individuals.complexioned individuals.  Sometimes, the skin texture may be slightly thickened.Sometimes, the skin texture may be slightly thickened.
  60. 60.  Occasionally, Becker's nevus may appear onOccasionally, Becker's nevus may appear on atypicalatypical sitessites such as the face, arms, low back & legs.such as the face, arms, low back & legs.  The patch enlarges slowly and in an irregular fashion toThe patch enlarges slowly and in an irregular fashion to give a geographic configuration; the ultimate sizegive a geographic configuration; the ultimate size ranges from a few to the usual 10-20 cm in diameter.ranges from a few to the usual 10-20 cm in diameter.  The hyperpigmentation may vary from light brown toThe hyperpigmentation may vary from light brown to dark brown.dark brown.
  61. 61.  Several months to years after the appearance of pigmentation,Several months to years after the appearance of pigmentation, thick brown-to-black hairs develop both within and in closethick brown-to-black hairs develop both within and in close proximity to the patch.proximity to the patch.  Hair density is highly variable andHair density is highly variable and occasionally,occasionally, hypertrichosis does not occur.hypertrichosis does not occur.  The central area in the patch may thicken, and acne vulgarisThe central area in the patch may thicken, and acne vulgaris may develop.may develop.  Once present, the patch remains indefinitely, although minimalOnce present, the patch remains indefinitely, although minimal pigmentary fading may occur in adulthood.pigmentary fading may occur in adulthood.
  62. 62. Pathophysiology:Pathophysiology: • The pathogenesis of Becker nevus remains uncertain.The pathogenesis of Becker nevus remains uncertain. • Androgens may play a role as evidenced by:Androgens may play a role as evidenced by: - Peripubertal development,- Peripubertal development, - Male preponderance,- Male preponderance, - Hypertrichosis,- Hypertrichosis, - Occasional development of acneform lesions within the patch- Occasional development of acneform lesions within the patch - Rare association with accessory scrotum in genital region.- Rare association with accessory scrotum in genital region. • In addition, a significant increase in the number of androgenIn addition, a significant increase in the number of androgen receptors in lesional skin has been reported.receptors in lesional skin has been reported.
  63. 63. Course and complicationsCourse and complications  A Becker's nevus may enlarge slowly for a year or twoA Becker's nevus may enlarge slowly for a year or two after presentation.after presentation.  It then stabilizes and appears to persist indefinitely,It then stabilizes and appears to persist indefinitely, although there may be some fading of the lesion in latealthough there may be some fading of the lesion in late adulthood.adulthood.  It is usually asymptomatic.It is usually asymptomatic.  A benign asymptomatic smooth muscle hamartomaA benign asymptomatic smooth muscle hamartoma may underlie a Becker's nevus.may underlie a Becker's nevus.
  64. 64.  Rarely, Becker's nevus may be associatedRarely, Becker's nevus may be associated with hypoplasia of underlying structures,with hypoplasia of underlying structures, e.g., hypoplasia of the breast ore.g., hypoplasia of the breast or shortening of the arm.shortening of the arm.
  65. 65. Other associations seen with Becker nevus include:Other associations seen with Becker nevus include:  Unilateral or ipsilateral pectoralis major aplasia,Unilateral or ipsilateral pectoralis major aplasia,  Ipsilateral limb shortening,Ipsilateral limb shortening,  Ipsilateral foot enlargement,Ipsilateral foot enlargement,  Spina bifida,Spina bifida,  Scoliosis,Scoliosis,  Pectus carinatum,Pectus carinatum,  Localized lipoatrophy,Localized lipoatrophy,  Congenital adrenal hyperplasia,Congenital adrenal hyperplasia,  Polythelia, andPolythelia, and  Accessory scrotum.Accessory scrotum.
  66. 66.  Becker nevus is considered a benign process; however, anBecker nevus is considered a benign process; however, an association with melanoma was discussed in a series of 9association with melanoma was discussed in a series of 9 patients in whom both Becker nevus and melanoma developed.patients in whom both Becker nevus and melanoma developed.  In this series, 5 patients developed melanoma on the sameIn this series, 5 patients developed melanoma on the same body site as the Becker nevus, but in 1 patient only didbody site as the Becker nevus, but in 1 patient only did melanoma develop within the Becker nevus.melanoma develop within the Becker nevus.
  67. 67. PathologyPathology  The epidermis shows slight acanthosis and papillomatosis.The epidermis shows slight acanthosis and papillomatosis.  There is hyperpigmentation of the basal layer.There is hyperpigmentation of the basal layer.  The number of melanocytes is usually normal or only slightlyThe number of melanocytes is usually normal or only slightly increased.increased.  The hair follicles appear normal.The hair follicles appear normal.  There is variable increase in dermal smooth muscle fibers.There is variable increase in dermal smooth muscle fibers.  Ultrastructural studies reveal an increased number ofUltrastructural studies reveal an increased number of melanosomes in the melanocytes and increased number and sizemelanosomes in the melanocytes and increased number and size of melanosome complexes in the keratinocytes.of melanosome complexes in the keratinocytes.  There is an increased expression of testosterone receptors, andThere is an increased expression of testosterone receptors, and this hormonal feature may account for the expression of the lesionthis hormonal feature may account for the expression of the lesion around puberty.around puberty.
  68. 68. Differential diagnosisDifferential diagnosis  A congenital Becker's nevus may be confused with aA congenital Becker's nevus may be confused with a congenital nevocellular nevus.congenital nevocellular nevus.  The latter is usually raised, more corrugated, and mayThe latter is usually raised, more corrugated, and may show variegation of pigment.show variegation of pigment.  Histologically, there is no difficulty differentiating theHistologically, there is no difficulty differentiating the two conditions, as Becker's nevus does not havetwo conditions, as Becker's nevus does not have nevocellular nevus cells.nevocellular nevus cells.
  69. 69. TreatmentTreatment  Because a Becker's nevus does not have any malignantBecause a Becker's nevus does not have any malignant potential, excision is usually not practical or advisable.potential, excision is usually not practical or advisable.  The skin hyperpigmentation may respond to therapyThe skin hyperpigmentation may respond to therapy with a pigmented lesion laserwith a pigmented lesion laser (e.g.,Q-switched ruby laser), but the results are(e.g.,Q-switched ruby laser), but the results are unpredictable and recurrences common.unpredictable and recurrences common.
  70. 70. Nevus SpilusNevus Spilus  Nevus spilus is a congenital, isolated benign lesionNevus spilus is a congenital, isolated benign lesion characterized by a CALM sprinkled with flat melanoticcharacterized by a CALM sprinkled with flat melanotic macules or with pigmented papules.macules or with pigmented papules.  The clustering of 1- to 2-mm pigmented lesions isThe clustering of 1- to 2-mm pigmented lesions is usually apparent, but a Wood's lamp may be requiredusually apparent, but a Wood's lamp may be required to identify the underlying CALM.to identify the underlying CALM.
  71. 71.  Histologic studies of the background CALM show aHistologic studies of the background CALM show a slight increase in the number of dopa-positiveslight increase in the number of dopa-positive melanocytes and epidermal hyperplasia.melanocytes and epidermal hyperplasia.  The darkly pigmented macules and papules areThe darkly pigmented macules and papules are junctional or compound nevi.junctional or compound nevi.  MMG have been described in this entity.MMG have been described in this entity.
  72. 72.  The relationship of nevus spilus to NF is unresolved.The relationship of nevus spilus to NF is unresolved.  Nevus spilus may be observed in patients with multipleNevus spilus may be observed in patients with multiple neurofibromas.neurofibromas.  Melanoma has been seen in fewer than a dozen casesMelanoma has been seen in fewer than a dozen cases of nevus spilus.of nevus spilus.
  73. 73. Seborrheic KeratosisSeborrheic Keratosis  Synonyms: senile wart, senile keratosis, seborrheicSynonyms: senile wart, senile keratosis, seborrheic verruca, verruca seborrhica, basal cell papilloma.verruca, verruca seborrhica, basal cell papilloma.  Seborrheic keratoses are benign skin tumors.Seborrheic keratoses are benign skin tumors.
  74. 74. Classification of benign epithelial tumorsClassification of benign epithelial tumors
  75. 75.  They are very common & most people will develop atThey are very common & most people will develop at least one such tumor in their lifetime, with manyleast one such tumor in their lifetime, with many developing hundreds of these lesions.developing hundreds of these lesions.  Seborrheic keratoses are most commonly found in theSeborrheic keratoses are most commonly found in the over-30 age group.over-30 age group.  These lesions can appear on any part of the bodyThese lesions can appear on any part of the body except the mucous membranes.except the mucous membranes.  When they occur on the trunk & are multiple,When they occur on the trunk & are multiple, seborrheic keratoses can be seen in a “Christmasseborrheic keratoses can be seen in a “Christmas tree” pattern, lying with their long axes alongtree” pattern, lying with their long axes along skin folds, or Blaschko's linesskin folds, or Blaschko's lines..
  76. 76.  Seborrheic keratoses typically begin as flat, sharplySeborrheic keratoses typically begin as flat, sharply demarcated, brown macules.demarcated, brown macules.  As they progress, they become polypoidal,with unevenAs they progress, they become polypoidal,with uneven surface.surface.  The surface usually shows “warty” topography withThe surface usually shows “warty” topography with multiple plugged follicles and fronds and is usually dullmultiple plugged follicles and fronds and is usually dull or lack luster.or lack luster.  Follicular prominence is one of the hallmarks ofFollicular prominence is one of the hallmarks of seborrheic keratosesseborrheic keratoses..  This can be due either to pale follicular plugs within aThis can be due either to pale follicular plugs within a darker lesion or to black or brown plugs within a paledarker lesion or to black or brown plugs within a pale lesion.lesion.
  77. 77.  Seborrheic keratoses typically have a “stuck-on”Seborrheic keratoses typically have a “stuck-on” appearance secondary to their somewhat polypoidalappearance secondary to their somewhat polypoidal morphology.morphology.  Colors of these lesions can vary from a pale brown withColors of these lesions can vary from a pale brown with pink tones to dark brown or black.pink tones to dark brown or black.  Some seborrheic keratoses can be almost whiteSome seborrheic keratoses can be almost white..
  78. 78.  A clinical variant of the typical seborrheicA clinical variant of the typical seborrheic keratosis described is a variant of smallkeratosis described is a variant of small polypoidal lesions commonly called “skin tags.”polypoidal lesions commonly called “skin tags.”  Distinct from smooth skin tags, these small, furrowed,Distinct from smooth skin tags, these small, furrowed, rough-surfaced polyps appear most commonly aroundrough-surfaced polyps appear most commonly around the neck, under the breast, or in the axillae.the neck, under the breast, or in the axillae.  They seem to have a predilection for points ofThey seem to have a predilection for points of chronic traumachronic trauma..
  79. 79.  They show a surface morphology similar to that of theThey show a surface morphology similar to that of the classic seborrheic keratosis, but their diameter isclassic seborrheic keratosis, but their diameter is frequently only 1 to 2 mm, with a height above the skinfrequently only 1 to 2 mm, with a height above the skin of sometimes more than 3 mm.of sometimes more than 3 mm.  These lesions may disappear spontaneously byThese lesions may disappear spontaneously by dropping off.dropping off.
  80. 80.  Lesions around the neck can catch on clothing, as canLesions around the neck can catch on clothing, as can lesions around the waist.lesions around the waist.  Others can grow to become cosmetically undesirable.Others can grow to become cosmetically undesirable.  Many can cause concern to the patient because ofMany can cause concern to the patient because of confusion with nevi and the thought that the lesion isconfusion with nevi and the thought that the lesion is becoming a malignant melanoma.becoming a malignant melanoma.  Conversely, dysplastic nevi or malignant melanomasConversely, dysplastic nevi or malignant melanomas can lurk in a forest of seborrheic keratoses and becan lurk in a forest of seborrheic keratoses and be undetected till a late stage,posing significant danger.undetected till a late stage,posing significant danger.
  81. 81. EtiologyEtiology  The etiology of seborrheic keratoses is not known.The etiology of seborrheic keratoses is not known.  In patients with a great number of lesions, it isIn patients with a great number of lesions, it is sometimes noted that there is a family history.sometimes noted that there is a family history.  This may well reflect a genetic propensity.This may well reflect a genetic propensity.  Are blamed, usually by the patient, to sun exposure.Are blamed, usually by the patient, to sun exposure.  There is little to support this other than a propensity forThere is little to support this other than a propensity for the large type of seborrheic keratoses to develop inthe large type of seborrheic keratoses to develop in areas of intermittent sun exposure, such as the backareas of intermittent sun exposure, such as the back and anterior chest.and anterior chest.  There does not seem to be a relationship withThere does not seem to be a relationship with skin type or with areas of sun exposure.skin type or with areas of sun exposure.
  82. 82.  B/c of the verrucous appearance of, HPV is suggestedB/c of the verrucous appearance of, HPV is suggested as a possible cause,but despite repeated searches,viralas a possible cause,but despite repeated searches,viral involvement has not been confirmed.involvement has not been confirmed.  Epidermal growth factorsEpidermal growth factors have been implicated inhave been implicated in the development of seborrheic keratoses.the development of seborrheic keratoses.  Melanocytic hyperplasia is commonly seen in seborrheicMelanocytic hyperplasia is commonly seen in seborrheic keratoses.keratoses.  It has been suggested thatIt has been suggested that melanocytes ormelanocytes or melanocyte-derived growth factorsmelanocyte-derived growth factors may have amay have a role in the dvt of seborrheic keratoses.role in the dvt of seborrheic keratoses.  However,causal relationship has not been determined.However,causal relationship has not been determined.
  83. 83.  The eruptive appearance of multiple seborrheicThe eruptive appearance of multiple seborrheic keratoses (keratoses (the sign of Leser-Trelatthe sign of Leser-Trelat)) in associationin association with various internal malignancies and withwith various internal malignancies and with concomitant ANconcomitant AN, suggests the possibility that:, suggests the possibility that:  AA tumor-derived circulating growth factortumor-derived circulating growth factor may bemay be involved in the pathogenesis of these lesions.involved in the pathogenesis of these lesions.  Such factor has not yet been identified with certainty,Such factor has not yet been identified with certainty, althoughalthough transforming growth factortransforming growth factor has beenhas been implicated.implicated.
  84. 84. Clinicopathologic Variants:Clinicopathologic Variants: 1-Common Seborrheic Keratosis1-Common Seborrheic Keratosis Synonyms: basal cell papilloma, solid seborrheic keratosis.Synonyms: basal cell papilloma, solid seborrheic keratosis.  This is considered the classic lesion.This is considered the classic lesion.  The configuration is mushroom-like with sharplyThe configuration is mushroom-like with sharply demarcated hyperplastic epidermis overhanging thedemarcated hyperplastic epidermis overhanging the surrounding skin.surrounding skin.  The tumor consists of uniform basaloid cells.The tumor consists of uniform basaloid cells.
  85. 85.  Keratin cysts are often prominent and may be follicularKeratin cysts are often prominent and may be follicular or extrafollicular.or extrafollicular.  Melanocytes are often present in considerable numbersMelanocytes are often present in considerable numbers and their pigment production results in the color of theand their pigment production results in the color of the darker lesions.darker lesions.  Pigment transfer to the keratinocytes appears to bePigment transfer to the keratinocytes appears to be normal.normal.
  86. 86. 2-Reticulated Seborrheic Keratosis2-Reticulated Seborrheic Keratosis Synonym:Synonym: adenoid seborrheic keratosis.adenoid seborrheic keratosis.  Thin cords of basaloid cells descend from the base ofThin cords of basaloid cells descend from the base of the epidermis.the epidermis.  Keratin cysts are embraced by these thin strands ofKeratin cysts are embraced by these thin strands of cells.cells.  A fine eosinophilic collagen stroma wraps around theseA fine eosinophilic collagen stroma wraps around these cords and can form much of the lesion.cords and can form much of the lesion.
  87. 87. 3-Clonal Seborrheic Keratosis3-Clonal Seborrheic Keratosis  Nests, usually but not always well defined, of round,Nests, usually but not always well defined, of round, loosely packed cells are present within the epidermis.loosely packed cells are present within the epidermis.  Although the predominant cell is the keratinocyte, theAlthough the predominant cell is the keratinocyte, the nests may contain large numbers of melanocytes.nests may contain large numbers of melanocytes.  The keratinocytes vary in size.The keratinocytes vary in size.
  88. 88. 4-Stucco Keratosis4-Stucco Keratosis Synonyms: hyperkeratotic seborrheic keratosis,acanthoticSynonyms: hyperkeratotic seborrheic keratosis,acanthotic seborrheic keratosis, verrucous seborrheic keratosis.seborrheic keratosis, verrucous seborrheic keratosis.  Stucco keratoses are typically gray-white in color.Stucco keratoses are typically gray-white in color.  They tend to be multiple, about 3- to 4-mm, andThey tend to be multiple, about 3- to 4-mm, and located on the legs.located on the legs.  Church spire–like projections of the epidermal cellsChurch spire–like projections of the epidermal cells around a collagen core thrust upward into aaround a collagen core thrust upward into a basketweave type of hyperkeratosis.basketweave type of hyperkeratosis.  The vacuolated keratinocytes seen in verruca vulgarisThe vacuolated keratinocytes seen in verruca vulgaris are not seen in this lesion, although clinically it canare not seen in this lesion, although clinically it can resemble a small viral wart.resemble a small viral wart.
  89. 89. 5-Irritated Seborrheic Keratosis5-Irritated Seborrheic Keratosis • Synonyms:Synonyms: inflamed seborrheic keratosis,inflamed seborrheic keratosis, basosquamous cell acanthoma.basosquamous cell acanthoma. • Eczematous changes can occur in and around anEczematous changes can occur in and around an otherwise typical seborrheic keratosis.otherwise typical seborrheic keratosis. • The cause of this eczematous reaction is unknown.The cause of this eczematous reaction is unknown. • Trauma may play a role, but in most instances there isTrauma may play a role, but in most instances there is no apparent antecedent event.no apparent antecedent event. • Histologically, an irritated seborrheic keratosis shows,Histologically, an irritated seborrheic keratosis shows, apart from inflammatory changes, many whorls orapart from inflammatory changes, many whorls or eddies of eosinophilic flattened squamous cellseddies of eosinophilic flattened squamous cells arranged in onionskin fashion.arranged in onionskin fashion.
  90. 90.  These resemble poorly differentiated keratin pearls inThese resemble poorly differentiated keratin pearls in squamous cell carcinoma but can be distinguished bysquamous cell carcinoma but can be distinguished by their large number, small size, and circumscribedtheir large number, small size, and circumscribed configuration.configuration.  Keratinocytes within an irritated seborrheic keratosisKeratinocytes within an irritated seborrheic keratosis show a higher degree of keratinization or moreshow a higher degree of keratinization or more complete maturation as compared with the commoncomplete maturation as compared with the common seborrheic keratosis; the mechanism for thisseborrheic keratosis; the mechanism for this phenomenon is unknown.phenomenon is unknown.
  91. 91. 6-Seborrheic Keratosis with Squamous Atypia6-Seborrheic Keratosis with Squamous Atypia  Cellular atypia and dyskeratosis can be seen in someCellular atypia and dyskeratosis can be seen in some seborrheic keratoses.seborrheic keratoses.  These lesions can closely mimic Bowen's disease orThese lesions can closely mimic Bowen's disease or invasive squamous cell carcinoma.invasive squamous cell carcinoma.  It is not known what causes these changes, whetherIt is not known what causes these changes, whether they are due to irritation/activation or whether they arethey are due to irritation/activation or whether they are precursors of SCC.precursors of SCC.  It seems prudent to remove these lesions completely.It seems prudent to remove these lesions completely.
  92. 92. 7-Melanoacanthoma7-Melanoacanthoma Synonym:Synonym: pigmented seborrheic keratosis.pigmented seborrheic keratosis.  Melanoacanthoma is more than a darkly pigmentedMelanoacanthoma is more than a darkly pigmented seborrheic keratosis.seborrheic keratosis.  Within the lesion there is striking proliferation ofWithin the lesion there is striking proliferation of dendritic melanocytes.dendritic melanocytes.  These melanocytes are engorged with melanin, but theThese melanocytes are engorged with melanin, but the surrounding keratinocytes contain hardly any melanin.surrounding keratinocytes contain hardly any melanin.  The melanocytes may proliferate as nests.The melanocytes may proliferate as nests.  This lesion has no malignant potential.This lesion has no malignant potential.
  93. 93. 8-Dermatosis Papulosa Nigra8-Dermatosis Papulosa Nigra  These small facial papules, originally described inThese small facial papules, originally described in African Americans but seen in darker-skinned personsAfrican Americans but seen in darker-skinned persons of many other races,of many other races,  Appear to be a variant of seborrheic keratosis.Appear to be a variant of seborrheic keratosis.  They resemble tiny melanoacanthomas.They resemble tiny melanoacanthomas.
  94. 94. Skin Cancer AssociationsSkin Cancer Associations • BCC and other common skin cancers have beenBCC and other common skin cancers have been reported, rarely, in association with seborrheicreported, rarely, in association with seborrheic keratoses.keratoses. • In a study of 4310 tumors clinically diagnosed asIn a study of 4310 tumors clinically diagnosed as seborrheic keratoses,60 (1.4 %) proved to be SCSIsitu.seborrheic keratoses,60 (1.4 %) proved to be SCSIsitu. • In another study of 108 seborrheic keratoses, a 4.6 %In another study of 108 seborrheic keratoses, a 4.6 % incidence of associated SCC was reported.incidence of associated SCC was reported. • Such lesions may represent a collision phenomenon.Such lesions may represent a collision phenomenon. • Prudence, though, dictates that seborrheic keratosesPrudence, though, dictates that seborrheic keratoses that have undergone rapid growth or are clinicallythat have undergone rapid growth or are clinically atypical be biopsied and that lesions demonstratingatypical be biopsied and that lesions demonstrating cellular atypia be completely removed.cellular atypia be completely removed.
  95. 95. The Sign of Leser-TrelatThe Sign of Leser-Trelat  Multiple eruptive seborrheic keratoses, also known asMultiple eruptive seborrheic keratoses, also known as thethe sign of Leser- Trelat,sign of Leser- Trelat, have been mentioned inhave been mentioned in association with multiple internal malignancies.association with multiple internal malignancies.  The frequent associations areThe frequent associations are adenocarcinomas ofadenocarcinomas of the stomach, colon, and breast.the stomach, colon, and breast.  This sign has also been reported with a variety of otherThis sign has also been reported with a variety of other tumors, including lymphomas, leukemias, & melanoma.tumors, including lymphomas, leukemias, & melanoma.  It has also been mentioned in association withIt has also been mentioned in association with hyperkeratosis of the palms and soles associated withhyperkeratosis of the palms and soles associated with malignant disease and with acanthosis nigricans.malignant disease and with acanthosis nigricans.
  96. 96.  A hallmark of many patients with so-called eruptiveA hallmark of many patients with so-called eruptive seborrheic keratoses is a cutaneous eruption that isseborrheic keratoses is a cutaneous eruption that is also inflammatory.also inflammatory.  It may well be that the inflammatory dermatosis isIt may well be that the inflammatory dermatosis is centering on skin papillomas and seborrheic keratoses,centering on skin papillomas and seborrheic keratoses, making them suddenly “appear.”making them suddenly “appear.”
  97. 97.  It is common clinical experience to see an increase inIt is common clinical experience to see an increase in the prominence of seborrheic keratoses in patients withthe prominence of seborrheic keratoses in patients with generalized dermatitis from any cause.generalized dermatitis from any cause.  If there is a relationship with cancer, it could beIf there is a relationship with cancer, it could be explained via growth factor or hormone effects onexplained via growth factor or hormone effects on keratinocytes, perhaps a mechanism similar to thatkeratinocytes, perhaps a mechanism similar to that involved in the production of acanthosis nigricans.involved in the production of acanthosis nigricans.  The true relationship of multiple eruptive seborrheicThe true relationship of multiple eruptive seborrheic keratoses to internal malignant disease remains to bekeratoses to internal malignant disease remains to be defined.defined.
  98. 98. TreatmentTreatment • Lesions that are bothering the patient functionally orLesions that are bothering the patient functionally or cosmetically can be treated.cosmetically can be treated. • Cryotherapy is the RX of choice for majority of lesions.Cryotherapy is the RX of choice for majority of lesions. • Following cryotherapy, postinflammatoryFollowing cryotherapy, postinflammatory hypopigmentation or hyperpigmentation may develop.hypopigmentation or hyperpigmentation may develop. • Although usually temporary, these pigmentary changesAlthough usually temporary, these pigmentary changes may persist in darker-skinned patients and can be mostmay persist in darker-skinned patients and can be most disturbing.disturbing. • Other treatment modalities include electrodesiccationOther treatment modalities include electrodesiccation followed by the removal of the lesion with a curette orfollowed by the removal of the lesion with a curette or curettage followed by light electrodesiccation.curettage followed by light electrodesiccation.
  99. 99.  Laser therapy using a pigmented lesion laser such asLaser therapy using a pigmented lesion laser such as the Q-switched ruby laser is also effective, and whenthe Q-switched ruby laser is also effective, and when used to treat flat seborrheic keratoses, it may carry aused to treat flat seborrheic keratoses, it may carry a lower risk of post-inflammatory pigmentation orlower risk of post-inflammatory pigmentation or scarring compared with cryotherapy orscarring compared with cryotherapy or electrodesiccation.electrodesiccation.
  100. 100.  Surgical excision is also effective but is usually not theSurgical excision is also effective but is usually not the treatment of choice in view of the certainty of scarring.treatment of choice in view of the certainty of scarring.  One of the greatest dangers posed by treating aOne of the greatest dangers posed by treating a “seborrheic keratosis” other than by surgical excision“seborrheic keratosis” other than by surgical excision and histologic revision is that the treated lesion couldand histologic revision is that the treated lesion could be a dysplastic nevus or a malignant melanoma.be a dysplastic nevus or a malignant melanoma.  It is strongly recommended that if the lesion is notIt is strongly recommended that if the lesion is not absolutely typical of seborrheic keratosis, it should beabsolutely typical of seborrheic keratosis, it should be submitted for histologic examination.submitted for histologic examination.
  101. 101. Disorders of MelanocytesDisorders of Melanocytes
  102. 102. ACQUIRED MELANOCYTIC NEVOCELLULAR NEVIACQUIRED MELANOCYTIC NEVOCELLULAR NEVI  Melanocytic nevocellular nevi are small (<1.0 cm),Melanocytic nevocellular nevi are small (<1.0 cm), circumscribed, acquired pigmented macules or papulescircumscribed, acquired pigmented macules or papules composed of groups of melanocytic nevus cells located in thecomposed of groups of melanocytic nevus cells located in the epidermis, dermis, and rarely, subcutaneous tissue.epidermis, dermis, and rarely, subcutaneous tissue.
  103. 103. EpidemiologyEpidemiology  One of the most common acquired new growths in CaucasiansOne of the most common acquired new growths in Caucasians (most adults have about 20 nevi), less common in blacks or(most adults have about 20 nevi), less common in blacks or pigmented peoples.pigmented peoples.  Dysplastic nevi, which are putative precursor lesions ofDysplastic nevi, which are putative precursor lesions of malignant melanoma, occur in 30 % of patients with primarymalignant melanoma, occur in 30 % of patients with primary melanoma and in 6 % of their family members.melanoma and in 6 % of their family members.  Risk of melanoma is related to the numbers of nevi.Risk of melanoma is related to the numbers of nevi.
  104. 104. HistoryHistory  Duration of LesionsDuration of Lesions These lesions, which are commonlyThese lesions, which are commonly calledcalled moles,moles, appear in early childhood and reach a maximum inappear in early childhood and reach a maximum in young adulthood.young adulthood.  There is a gradual involution of lesions, and most disappear byThere is a gradual involution of lesions, and most disappear by age 60 (the dermal melanocytic nevocellular nevus does notage 60 (the dermal melanocytic nevocellular nevus does not disappear).disappear).  Dysplastic nevi continue to appear throughout life and areDysplastic nevi continue to appear throughout life and are believed not to involute.believed not to involute.
  105. 105. Skin SymptomsSkin Symptoms  Nevocellular nevi are asymptomatic, and if a lesion persistentlyNevocellular nevi are asymptomatic, and if a lesion persistently itches or is tender, it should be followed carefully or excised,itches or is tender, it should be followed carefully or excised, since pruritus, may be an early indication of malignant change.since pruritus, may be an early indication of malignant change.
  106. 106. Classification:Classification: 1-Junctional Melanocytic NCN1-Junctional Melanocytic NCN  Cells at the dermal-epidermal junction above the basementCells at the dermal-epidermal junction above the basement membrane. (on the epidermal site of the basement membrane,membrane. (on the epidermal site of the basement membrane, they are intraepidermal.)they are intraepidermal.) 2-Compound Melanocytic NCN2-Compound Melanocytic NCN A combination of the histologicA combination of the histologic features of the junctional and dermal.features of the junctional and dermal.  Nevus cells invade the papillary dermis, and nevus cell nestsNevus cells invade the papillary dermis, and nevus cell nests are found both intraepidermally and dermally.are found both intraepidermally and dermally.
  107. 107. 3.3. Dermal melanocytic NCNDermal melanocytic NCN:: These represent the last stage of the evolution of NCN.These represent the last stage of the evolution of NCN. Cells exclusively in the dermisCells exclusively in the dermis.. ““Dropping off” (Dropping off” (AbtropfungAbtropfung) into the dermis is now completed, and) into the dermis is now completed, and the nevus grows or rests intradermally.the nevus grows or rests intradermally.
  108. 108. Evolution:Evolution:  Melanocytic NCN develop during childhood and usually haveMelanocytic NCN develop during childhood and usually have reached their final number by adolescence,reached their final number by adolescence,  Though some NCN may arise during adulthood (note theThough some NCN may arise during adulthood (note the difference with Clark’s nevi,).difference with Clark’s nevi,).  All NCN undergo a predetermined evolution, which usuallyAll NCN undergo a predetermined evolution, which usually results in involution and fibrosis in time.results in involution and fibrosis in time.  With progressive age, there will be gradual fibrosis.With progressive age, there will be gradual fibrosis.
  109. 109.  Since common melanocytic NCN lose their capacity forSince common melanocytic NCN lose their capacity for melanization, the further the nevus cells penetrate into themelanization, the further the nevus cells penetrate into the dermis, the lesser is the intensity of pigmentation with thedermis, the lesser is the intensity of pigmentation with the increase in the dermal proportion of the nevus.increase in the dermal proportion of the nevus.  Purely dermal NCN are therefore almost alwaysPurely dermal NCN are therefore almost always without pigment.without pigment.
  110. 110. I-Junctional Melanocytic Nevocellular NeviI-Junctional Melanocytic Nevocellular Nevi Skin Lesions:Skin Lesions: Macule, or only very slightly raised.Macule, or only very slightly raised.  SIZESIZE IfIf ..1.0 cm, the mole is a congenital nevomelanocytic1.0 cm, the mole is a congenital nevomelanocytic nevus or a dysplastic melanocytic nevus.nevus or a dysplastic melanocytic nevus.  COLORCOLOR Uniform tan, brown, or dark brownUniform tan, brown, or dark brown  SHAPESHAPE Round or oval with smooth, regular bordersRound or oval with smooth, regular borders  ARRANGEMENTARRANGEMENT Scattered discrete lesionsScattered discrete lesions  DISTRIBUTION:DISTRIBUTION: RandomRandom  SITES OF PREDILECTIONSITES OF PREDILECTION Trunk, upper extremities, face,Trunk, upper extremities, face, lower extremities, occasionally palmar and plantar.lower extremities, occasionally palmar and plantar. Differential DiagnosisDifferential Diagnosis  Tan/Brown/Black MaculeTan/Brown/Black Macule Solar lentigo, lentigo maligna.Solar lentigo, lentigo maligna.
  111. 111. Junctional NMNJunctional NMN
  112. 112. II-Compound Melanocytic Nevocellular NeviII-Compound Melanocytic Nevocellular Nevi  Compound melanocytic nevocellular nevi represent aCompound melanocytic nevocellular nevi represent a combination of junctional and dermal NCN and are usuallycombination of junctional and dermal NCN and are usually darkly pigmented (junctional component ofdarkly pigmented (junctional component of NCN),elevated, and often papillomatous due to theirNCN),elevated, and often papillomatous due to their dermal component.dermal component.
  113. 113. Skin Lesions:Skin Lesions: Papules or nodules.Papules or nodules.  COLORCOLOR Dark brown, sometimes even black; color mayDark brown, sometimes even black; color may become mottled as progressive conversion into dermal NCNbecome mottled as progressive conversion into dermal NCN occurs.occurs.  SHAPESHAPE Round, dome-shaped, smooth, occasionallyRound, dome-shaped, smooth, occasionally papillomatous or hyperkeratotic, often associated with bristle-papillomatous or hyperkeratotic, often associated with bristle- like terminal hairs.like terminal hairs.  DISTRIBUTIONDISTRIBUTION Face, scalp, trunk, extremities.Face, scalp, trunk, extremities.
  114. 114. Differential DiagnosisDifferential Diagnosis  Tan/Brown/Black Papule :Tan/Brown/Black Papule :  Seborrheic keratosis,Seborrheic keratosis,  Dermatofibroma,Dermatofibroma,  Dysplastic nevus,Dysplastic nevus,  Spitz nevus, blue nevus, and nodular melanoma must beSpitz nevus, blue nevus, and nodular melanoma must be considered.considered.
  115. 115. Compound NMNCompound NMN
  116. 116. III-Dermal Melanocytic Nevocellular NeviIII-Dermal Melanocytic Nevocellular Nevi Skin Lesions:Skin Lesions: Papule or Nodule,Papule or Nodule,  COLORCOLOR Skin-colored, tan, brown, or flecks of brown, often withSkin-colored, tan, brown, or flecks of brown, often with telangiectasia.telangiectasia.  SHAPESHAPE Round, dome-shaped.Round, dome-shaped.  DISTRIBUTIONDISTRIBUTION More common on the face and neck but canMore common on the face and neck but can occur on the trunk or extremitiesoccur on the trunk or extremities  OTHER FEATURESOTHER FEATURES Usually present in the second or thirdUsually present in the second or third decade. Older lesions, mostly on the trunk, may becomedecade. Older lesions, mostly on the trunk, may become papillomatous or pedunculated and do not disappearpapillomatous or pedunculated and do not disappear spontaneously.spontaneously.
  117. 117. Differential Diagnosis:Differential Diagnosis: Skin-Colored PapuleSkin-Colored Papule  Basal cell carcinoma,Basal cell carcinoma,  Neurofibroma,Neurofibroma,  Trichoepithelioma,Trichoepithelioma,  Sebaceous hyperplasia,Sebaceous hyperplasia,  Dermatofibroma.Dermatofibroma.
  118. 118. HALO NEVOMELANOCYTIC NEVUSHALO NEVOMELANOCYTIC NEVUS  This lesion is a nevomelanocytic nevus that is encircled by aThis lesion is a nevomelanocytic nevus that is encircled by a halo of leukoderma or depigmentation.halo of leukoderma or depigmentation.  The leukoderma is based on a decrease of melanin inThe leukoderma is based on a decrease of melanin in melanocytes or disappearance of melanocytes at the DEJ.melanocytes or disappearance of melanocytes at the DEJ.  Halo nevi often undergo spontaneous involution and often withHalo nevi often undergo spontaneous involution and often with regression of the centrally located pigmented nevus.regression of the centrally located pigmented nevus. Synonym:Synonym: Sutton’s leukoderma acquisitum centrifugumSutton’s leukoderma acquisitum centrifugum..
  119. 119. Epidemiology and EtiologyEpidemiology and Etiology  AgeAge First three decades,First three decades,  Race and SexRace and Sex All races, both sexes,All races, both sexes,  IncidenceIncidence Occurs in patients with vitiligo, 18 % to 26 %. MayOccurs in patients with vitiligo, 18 % to 26 %. May herald vitiligo.herald vitiligo.  Family HistoryFamily History Halo nevi occur in siblings and with history ofHalo nevi occur in siblings and with history of vitiligo in family.vitiligo in family.  Associated DisordersAssociated Disorders Vitiligo, metastatic melanoma (aroundVitiligo, metastatic melanoma (around lesions and around nevus cell nevi).lesions and around nevus cell nevi).
  120. 120. HistoryHistory Three StagesThree Stages 1-Development (in months) of halo around preexisting nevus cell1-Development (in months) of halo around preexisting nevus cell nevus.nevus. Halo may be preceded by faint erythema,Halo may be preceded by faint erythema, 2. Disappearance (months to years) of nevus cell nevus2. Disappearance (months to years) of nevus cell nevus 3. Repigmentation (months to years) of halo.3. Repigmentation (months to years) of halo.
  121. 121. Physical Examination:Physical Examination: Skin Lesions: -Skin Lesions: - Papular brown nevus (5.0mm) with halo,Papular brown nevus (5.0mm) with halo, - Sharply marginated hypomelanosis.- Sharply marginated hypomelanosis. - The nevus is centrally located.- The nevus is centrally located. SHAPESHAPE Oval or round hypomelanosisOval or round hypomelanosis ARRANGEMENTARRANGEMENT Scattered discrete lesions (1- 90),Scattered discrete lesions (1- 90), DISTRIBUTIONDISTRIBUTION Trunk (same as distribution of nevus cellTrunk (same as distribution of nevus cell nevus).nevus).
  122. 122. Differential DiagnosisDifferential Diagnosis  ““Halo” Depigmentation around Other LesionsHalo” Depigmentation around Other Lesions Can occurCan occur around blue nevus,congenital garment nevus cell nevus, Spitz’saround blue nevus,congenital garment nevus cell nevus, Spitz’s juvenile nevus, verruca plana, primary melanoma,juvenile nevus, verruca plana, primary melanoma, dermatofibroma, and neurofibroma.dermatofibroma, and neurofibroma. DermatopathologyDermatopathology  Nevus Cell NevusNevus Cell Nevus Junctional dermal or compound nevusJunctional dermal or compound nevus surrounded by lymphocytic infiltrate (lymphocytes andsurrounded by lymphocytic infiltrate (lymphocytes and histiocytes) around and between nevus cells.histiocytes) around and between nevus cells.  Nevus cells develop evidence of cell damage & disappear.Nevus cells develop evidence of cell damage & disappear.  Halo (Epidermis)Halo (Epidermis) Decrease or total absence of melanin andDecrease or total absence of melanin and melanocytes (as shown by electron microscopy)melanocytes (as shown by electron microscopy) DiagnosisDiagnosis  If clinical findings atypical, confirm histologicallyIf clinical findings atypical, confirm histologically
  123. 123. PathophysiologyPathophysiology  Immunologic phenomena are responsible for the dynamicImmunologic phenomena are responsible for the dynamic changes through the action of circulating cytotoxic antibodieschanges through the action of circulating cytotoxic antibodies and/or cytotoxic lymphocytes.and/or cytotoxic lymphocytes.  This disease awaits a reevaluation using newer techniques.This disease awaits a reevaluation using newer techniques.
  124. 124. CourseCourse  The lesions undergo spontaneous resolution.The lesions undergo spontaneous resolution.  Nevus cell nevi within the halo always must be evaluated forNevus cell nevi within the halo always must be evaluated for clinical criteria of malignancyclinical criteria of malignancy (variegation of pigment &(variegation of pigment & irregular borders)irregular borders) because a halo can and does occasionallybecause a halo can and does occasionally develop around primary malignant melanoma.develop around primary malignant melanoma. ManagementManagement  Reassurance.Reassurance.  ExcisionExcision If clinical findings are atypical, diagnosisIf clinical findings are atypical, diagnosis uncertain, lesion should be exciseduncertain, lesion should be excised..
  125. 125. BLUE NEVUS:BLUE NEVUS:  A blue nevus is an acquired, benign, firm, dark-blue to gray-to-A blue nevus is an acquired, benign, firm, dark-blue to gray-to- black, sharply defined papule or nodule representing a localizedblack, sharply defined papule or nodule representing a localized proliferation of melanin-producing dermal melanocytes.proliferation of melanin-producing dermal melanocytes.  Synonyms:Synonyms: Blue neuronevus, dermal melanocytoma.Blue neuronevus, dermal melanocytoma.
  126. 126. Epidemiology:Epidemiology:  AgeAge Onset in late adolescence,Onset in late adolescence,  SexSex Equal distribution,Equal distribution,  VariantsVariants Cellular blue nevus, combined blue nevus–Cellular blue nevus, combined blue nevus– nevomelanocytic nevus.nevomelanocytic nevus. HistoryHistory  Nearly always asymptomatic, occasionally of cosmetic concern.Nearly always asymptomatic, occasionally of cosmetic concern.  Appearance gradual and often not observed by patient orAppearance gradual and often not observed by patient or parents.parents.
  127. 127. Physical ExaminationPhysical Examination Skin LesionsSkin Lesions Papules to nodules usually <10.0 mm in diameter.Papules to nodules usually <10.0 mm in diameter. COLORCOLOR -- Blue, blue-gray, blue-black.Blue, blue-gray, blue-black. - Occasionally has target-like pattern of pigmentation.- Occasionally has target-like pattern of pigmentation. SHAPESHAPE Usually round to oval.Usually round to oval. PALPATIONPALPATION Firm.Firm. SITE:SITE: -- Most common on dorsa of hands or feet;Most common on dorsa of hands or feet; - May occur at any site.- May occur at any site.
  128. 128. Differential DiagnosisDifferential Diagnosis Blue/Gray Papule:Blue/Gray Papule:  Dermatofibroma,Dermatofibroma,  Glomus tumor,Glomus tumor,  Primary (nodular) or metastatic melanoma,Primary (nodular) or metastatic melanoma,  Pigmented spindle cell (Spitz) nevus,Pigmented spindle cell (Spitz) nevus,  Traumatic tattoo.Traumatic tattoo.
  129. 129. DermatopathologyDermatopathology  Melanin-containing fibroblast-like dermal melanocytes groupedMelanin-containing fibroblast-like dermal melanocytes grouped in irregular bundles admixed with melanin-containingin irregular bundles admixed with melanin-containing macrophages; excessive fibrous tissue production in uppermacrophages; excessive fibrous tissue production in upper reticular dermis. Epidermis normal.reticular dermis. Epidermis normal. DiagnosisDiagnosis  Usually made on clinical findings including epiluminescenceUsually made on clinical findings including epiluminescence microscopy, at times confirmed by excision andmicroscopy, at times confirmed by excision and dermatopathologic examination to rule out nodular melanomadermatopathologic examination to rule out nodular melanoma
  130. 130. PathogenesisPathogenesis  Probably represents ectopic accumulations of melanin-Probably represents ectopic accumulations of melanin- producing melanocytes in the dermis during their migration fromproducing melanocytes in the dermis during their migration from neural crest to sites in the skin.neural crest to sites in the skin. Course and PrognosisCourse and Prognosis  Most remain unchanged.Most remain unchanged.  Malignant melanoma rarely develops in blue nevi.Malignant melanoma rarely develops in blue nevi.
  131. 131. ManagementManagement  Blue nevi smaller than 10.0 mm in diameter and stable forBlue nevi smaller than 10.0 mm in diameter and stable for many years usually do not need excision.many years usually do not need excision.  Sudden appearance or change of an apparent blue nevusSudden appearance or change of an apparent blue nevus warrants surgical excision and dermatopathologic examination.warrants surgical excision and dermatopathologic examination.
  132. 132. SPITZ NEVUSSPITZ NEVUS  Spitz nevus is a benign, dome-shaped, hairless, smallSpitz nevus is a benign, dome-shaped, hairless, small (1.0 cm in diameter) nodule, most often pink or tan.(1.0 cm in diameter) nodule, most often pink or tan.  About half the patients are children.About half the patients are children.  The clinical presentation is distinctive, and there is often aThe clinical presentation is distinctive, and there is often a history of recent rapid growth.history of recent rapid growth.  However, the pathology of Spitz nevus is misleading, consistingHowever, the pathology of Spitz nevus is misleading, consisting of spindle and epithelioid nevus cells, some of which may beof spindle and epithelioid nevus cells, some of which may be atypical.atypical.  Differentiation from nodular malignant melanoma may requireDifferentiation from nodular malignant melanoma may require an experienced dermatopathologist.an experienced dermatopathologist. Synonyms:Synonyms: Spitz tumor, formerly also juvenile melanoma, epithelioidSpitz tumor, formerly also juvenile melanoma, epithelioid cell–spindle cell nevomelanocytic nevus.cell–spindle cell nevomelanocytic nevus.
  133. 133. EpidemiologyEpidemiology  IncidenceIncidence 1.4 : 100,000 (Australia)1.4 : 100,000 (Australia)  Age:Age:  Occurs at all ages.Occurs at all ages.  A third of the patients are children under 10 years of age, aA third of the patients are children under 10 years of age, a third are 10 to 20 years old, and a third are older than 20; rarelythird are 10 to 20 years old, and a third are older than 20; rarely seen in persons 40 years of age or older.seen in persons 40 years of age or older. HistoryHistory  Onset of LesionsOnset of Lesions Recent (within months). The large majorityRecent (within months). The large majority of the lesions (of the lesions (..90 %) are acquired.90 %) are acquired.  Skin SymptomsSkin Symptoms NoneNone  Family HistoryFamily History NoneNone
  134. 134. Physical ExaminationPhysical Examination  Skin LesionsSkin Lesions Papule or nodule, smooth-topped, hairless.Papule or nodule, smooth-topped, hairless.  COLORCOLOR Uniform pink , tan , brown, dark brownUniform pink , tan , brown, dark brown  SHAPE OF INDIVIDUAL LESIONSHAPE OF INDIVIDUAL LESION Round, dome-shaped,Round, dome-shaped, well-circumscribed nodule.well-circumscribed nodule.  DISTRIBUTIONDISTRIBUTION Head and neck.Head and neck.
  135. 135. Spitz nevusSpitz nevus
  136. 136. Nevus spilusNevus spilus
  137. 137. Spitz nevusSpitz nevus
  138. 138. Differential DiagnosisDifferential Diagnosis  Pink or Tan PapulePink or Tan Papule Pigmented spindle cell nevus ofPigmented spindle cell nevus of Reed is considered by many to be a variant of SpitzReed is considered by many to be a variant of Spitz nevus.nevus.  The tumor is dome-shaped, deeply pigmented, andThe tumor is dome-shaped, deeply pigmented, and often surrounded by a lighter brown regular rim;often surrounded by a lighter brown regular rim; epiluminescence is particularly helpful; the tumor cellsepiluminescence is particularly helpful; the tumor cells are not “diffusely infiltrating,” as in the Spitz nevus, butare not “diffusely infiltrating,” as in the Spitz nevus, but grow in a compact nodular pattern.grow in a compact nodular pattern.  Other lesions in the differential diagnosis are pyogenicOther lesions in the differential diagnosis are pyogenic granuloma, hemangioma, molluscum contagiosum,granuloma, hemangioma, molluscum contagiosum, juvenile xanthogranuloma, mastocytoma,juvenile xanthogranuloma, mastocytoma, dermatofibroma, atypical melanocytic nevi, nodulardermatofibroma, atypical melanocytic nevi, nodular melanoma,and dermal melanocytic nevus.melanoma,and dermal melanocytic nevus.
  139. 139. DermatopathologyDermatopathology LIGHT MICROSCOPYLIGHT MICROSCOPY  SiteSite Reticular dermis and epidermisReticular dermis and epidermis ProcessProcess Hyperplasia of epidermis, neoplasm of melanocytes,Hyperplasia of epidermis, neoplasm of melanocytes, dilatation of capillariesdilatation of capillaries  Cell TypesCell Types Admixed large epithelioid cells, largeAdmixed large epithelioid cells, large spindle cells with abundant cytoplasm, occasionalspindle cells with abundant cytoplasm, occasional mitotic figures; there are sometimes bizarre cytologicmitotic figures; there are sometimes bizarre cytologic patterns; nests of large cells extend from thepatterns; nests of large cells extend from the epidermis (“raining down”) into the reticular dermis asepidermis (“raining down”) into the reticular dermis as fascicles of cells form an “inverted triangle,” with thefascicles of cells form an “inverted triangle,” with the base lying at the dermal-epidermal junction and thebase lying at the dermal-epidermal junction and the apex in the reticular dermis.apex in the reticular dermis.
  140. 140. DiagnosisDiagnosis  Although the clinical appearance and recent growthAlthough the clinical appearance and recent growth are characteristic of a Spitz nevus, histologicare characteristic of a Spitz nevus, histologic examination must be done to confirm the clinicalexamination must be done to confirm the clinical diagnosis.diagnosis. ..
  141. 141. SignificanceSignificance  Excision in its entirety is important because the condition recursExcision in its entirety is important because the condition recurs in 10 % to 15 % of all cases in lesions that have not beenin 10 % to 15 % of all cases in lesions that have not been excised completely.excised completely.  This tumor poses some special problems in cytologic diagnosis.This tumor poses some special problems in cytologic diagnosis. Atypical lesions are worrisome.Atypical lesions are worrisome.  While the majority of Spitz nevi are benign, there can be aWhile the majority of Spitz nevi are benign, there can be a histologic similarity between Spitz nevi and melanoma. Also,histologic similarity between Spitz nevi and melanoma. Also, atypical Spitz nevi can occur and even have occasionalatypical Spitz nevi can occur and even have occasional “metastases” from such lesions. Melanoma has been reported“metastases” from such lesions. Melanoma has been reported to arise rarely in Spitz nevi.to arise rarely in Spitz nevi.
  142. 142. Course and PrognosisCourse and Prognosis  Spitz tumors probably do not involute, as do common acquiredSpitz tumors probably do not involute, as do common acquired nevomelanocytic nevi.nevomelanocytic nevi.  However, some lesions have been observed to transform intoHowever, some lesions have been observed to transform into common compound NMC, some undergo fibrosis and in latecommon compound NMC, some undergo fibrosis and in late stages may resemble dermatofibromas.stages may resemble dermatofibromas. ManagementManagement  Excision with a border of 5 mm.Excision with a border of 5 mm.  Follow-up in 6 to 12 months is advised, especially for atypicalFollow-up in 6 to 12 months is advised, especially for atypical lesions.lesions.
  143. 143. Congenital neviCongenital nevi  Congenital nevi are present at birth & resultCongenital nevi are present at birth & result from a proliferation offrom a proliferation of benign melanocytes inbenign melanocytes in the dermis, epidermis, or both.the dermis, epidermis, or both.  Occasionally, nevi that are not present at birthOccasionally, nevi that are not present at birth but are histologically identical to congenital nevibut are histologically identical to congenital nevi may develop during the first 2 years of life.may develop during the first 2 years of life.  This is referred to asThis is referred to as congenital nevuscongenital nevus tardive.tardive.
  144. 144. Pathophysiology:Pathophysiology:  The etiology of congenital melanocytic nevi remains unclear.The etiology of congenital melanocytic nevi remains unclear.  The melanocytes of the skin originate in the neuroectoderm,The melanocytes of the skin originate in the neuroectoderm, although the specific cell type from which they derive remainsalthough the specific cell type from which they derive remains unknown.unknown.  One hypothesis is that pluripotential nerve sheath precursorOne hypothesis is that pluripotential nerve sheath precursor cells migrate from the neural crest to the skin along paraspinalcells migrate from the neural crest to the skin along paraspinal ganglia and peripheral nerve sheaths and differentiate intoganglia and peripheral nerve sheaths and differentiate into melanocytes upon reaching the skin.melanocytes upon reaching the skin.  Congenital melanocytic nevi is that an external insult results inCongenital melanocytic nevi is that an external insult results in a mutation that affects the morphogenesis of the embryonica mutation that affects the morphogenesis of the embryonic neuroectoderm and migration of precursor cells to the skin.neuroectoderm and migration of precursor cells to the skin.
  145. 145. Stratified into 3 groups according to size:Stratified into 3 groups according to size: 1-Small nevi are less than 1.5 cm in greatest diameter,1-Small nevi are less than 1.5 cm in greatest diameter, 2-Medium nevi are 1.5-19.9 cm in greatest diameter, and2-Medium nevi are 1.5-19.9 cm in greatest diameter, and 3-Large or giant nevi are > 20 cm in greatest diameter3-Large or giant nevi are > 20 cm in greatest diameter..
  146. 146. Giant nevi are often surrounded by several smaller satellite nevi.Giant nevi are often surrounded by several smaller satellite nevi.  An alternate definition is that a small congenital nevus is one forAn alternate definition is that a small congenital nevus is one for which primary closure is possible after excision.which primary closure is possible after excision.  Congenital nevi may also be seen as a component ofCongenital nevi may also be seen as a component of neurocutaneous melanosisneurocutaneous melanosis, a rare congenital syndrome, a rare congenital syndrome characterized by the presence of congenital melanocytic nevicharacterized by the presence of congenital melanocytic nevi and melanotic neoplasms of the central nervous system.and melanotic neoplasms of the central nervous system.
  147. 147. The current diagnostic criteria forThe current diagnostic criteria for neurocutaneous melanosis are:neurocutaneous melanosis are: 1-Large (>20 cm) or multiple (>3) congenital nevi in association1-Large (>20 cm) or multiple (>3) congenital nevi in association with meningeal melanosis or melanoma,with meningeal melanosis or melanoma, 2-No evidence of meningeal melanoma except in patients in2-No evidence of meningeal melanoma except in patients in whom cutaneous lesions are histologically benign, andwhom cutaneous lesions are histologically benign, and 3-No evidence of cutaneous melanoma except in patients in3-No evidence of cutaneous melanoma except in patients in whom meningeal lesions are histologically benign .whom meningeal lesions are histologically benign .
  148. 148.  Neurocutaneous melanosis may result from an error in theNeurocutaneous melanosis may result from an error in the morphogenesis of the neuroectoderm, which gives rise tomorphogenesis of the neuroectoderm, which gives rise to the melanotic cells of both the skin and meninges.the melanotic cells of both the skin and meninges.  Clinically, patients may present with increased intracranialClinically, patients may present with increased intracranial pressure due to hydrocephalus or a mass lesion.pressure due to hydrocephalus or a mass lesion.  The prognosis of patients with symptomatic neurocutaneousThe prognosis of patients with symptomatic neurocutaneous melanosis is very poor, even in the absence of malignancy.melanosis is very poor, even in the absence of malignancy.  In one review of 39 reported cases of symptomaticIn one review of 39 reported cases of symptomatic neurocutaneous melanosis, death occurred in more than halfneurocutaneous melanosis, death occurred in more than half the patients within 3 years of the onset of neurologicalthe patients within 3 years of the onset of neurological symptoms, and most deaths were in patients younger than 10symptoms, and most deaths were in patients younger than 10 years.years.
  149. 149. Frequency:Frequency: Internationally:Internationally: present in 1-2% of newborn infants.present in 1-2% of newborn infants. Race:Race: NoNo racial predilection is recognized.racial predilection is recognized.  Sex:Sex: Congenital nevi occur in both sexes, with no knownCongenital nevi occur in both sexes, with no known predilection.predilection.  Age:Age: To be considered congenital nevi, lesions must beTo be considered congenital nevi, lesions must be present at birth.present at birth.
  150. 150. Mortality/Morbidity:Mortality/Morbidity:  For giant congenital melanocytic nevi, the risk ofFor giant congenital melanocytic nevi, the risk of developing melanoma has been reported to be asdeveloping melanoma has been reported to be as high as 5-7% by age 60 years.high as 5-7% by age 60 years.  Risk of melanoma may be greater in those with giantRisk of melanoma may be greater in those with giant congenital melanocytic nevi withcongenital melanocytic nevi with more satellitemore satellite lesions or a larger diameter.lesions or a larger diameter.  However, while the general consensus regardingHowever, while the general consensus regarding smaller nevi is that they pose a greater risk for thesmaller nevi is that they pose a greater risk for the development of melanoma than normal skin, this riskdevelopment of melanoma than normal skin, this risk has not been quantified.has not been quantified.
  151. 151. DDx:DDx:  Becker nevusBecker nevus  Spitz nevus,Spitz nevus,  Seborrheic keratosis,Seborrheic keratosis,  Pagets disease,mammary,Pagets disease,mammary,  Nevus sebacus,Nevus sebacus,  Melanocytic nevi,Melanocytic nevi,  Nevi of ito & ota,Nevi of ito & ota,  Neurofibromatosis,Neurofibromatosis,  Malignant melanoma,Malignant melanoma,  Halo nevus,Halo nevus,  Epidermal nevus syndrome,Epidermal nevus syndrome,  Epidermal nevusEpidermal nevus  Nevus spilusNevus spilus  Pigmented non-melanoma carcinomaPigmented non-melanoma carcinoma Mx;Mx;
  152. 152. Ageminated nevusAgeminated nevus
  153. 153. Nevomelanocytic neviNevomelanocytic nevi Etiology and PathogenesisEtiology and Pathogenesis  Congenital and acquired nevomelanocytic nevi areCongenital and acquired nevomelanocytic nevi are presumed to occur as the result of a developmentalpresumed to occur as the result of a developmental defect in neural crest-derived melanoblasts.defect in neural crest-derived melanoblasts.  This defect probably occurs after 10 weeks in utero butThis defect probably occurs after 10 weeks in utero but before the sixth uterine month; the occurrence of thebefore the sixth uterine month; the occurrence of the “split” nevus of the eyelid is an indication that“split” nevus of the eyelid is an indication that nevomelanocytes migrating from the neural crest werenevomelanocytes migrating from the neural crest were in place in this site before the eyelids split (24 weeks).in place in this site before the eyelids split (24 weeks).
  154. 154. Course and PrognosisCourse and Prognosis  By definition, CNN appear at birth, but varieties of CNNBy definition, CNN appear at birth, but varieties of CNN may arise during infancy (so-called tardive CNN).may arise during infancy (so-called tardive CNN).  The life history of CNN is not documented, butThe life history of CNN is not documented, but  CNN have been observed in elderly persons, an ageCNN have been observed in elderly persons, an age when acquired nevomelanocytic nevi have disappeared.when acquired nevomelanocytic nevi have disappeared.  Very large or giant CNN:Very large or giant CNN: The lifetime risk forThe lifetime risk for development of melanoma in largedevelopment of melanoma in large  CNN has been estimated to be at least 6.3 %; in 50 %CNN has been estimated to be at least 6.3 %; in 50 % of patients who develop melanoma in large CNN, theof patients who develop melanoma in large CNN, the diagnosis is made between the ages of 3 and 5 years.diagnosis is made between the ages of 3 and 5 years.  Melanoma that develops in a large CNN has a poorMelanoma that develops in a large CNN has a poor prognosis.prognosis.  Small CNN:Small CNN: The lifetime risk of developing malignantThe lifetime risk of developing malignant melanoma is 1 % to 5 %.melanoma is 1 % to 5 %.
  155. 155. Congenital nevomelanocytic neviCongenital nevomelanocytic nevi
  156. 156. Congenital nevomelanocytic neviCongenital nevomelanocytic nevi
  157. 157. Very Large (“Giant”) CNNVery Large (“Giant”) CNN
  158. 158.  Giant CNN of the head and neck may beGiant CNN of the head and neck may be associated with involvement of theassociated with involvement of the leptomeninges with the same pathologicleptomeninges with the same pathologic process; this presentation may beprocess; this presentation may be asymptomatic or be manifested by seizures,asymptomatic or be manifested by seizures, focal neurologic defects, or obstructivefocal neurologic defects, or obstructive hydrocephalus.hydrocephalus.
  159. 159.  Differential DiagnosisDifferential Diagnosis  Common acquired nevomelanocytic nevi, dysplasticCommon acquired nevomelanocytic nevi, dysplastic melanocytic nevi, congenital blue nevus, nevus spilus,melanocytic nevi, congenital blue nevus, nevus spilus, Becker’s nevus, pigmented epidermal nevi, and caféau-Becker’s nevus, pigmented epidermal nevi, and caféau- lait macules should be considered in the differentiallait macules should be considered in the differential diagnosis of CNN.diagnosis of CNN.  Small CNN are virtually indistinguishable clinically fromSmall CNN are virtually indistinguishable clinically from common acquired nevomelanocytic nevi except for size,common acquired nevomelanocytic nevi except for size, and lesions >1.5 cm may be presumed to be eitherand lesions >1.5 cm may be presumed to be either CNN or dysplastic melanocytic nevi.CNN or dysplastic melanocytic nevi.  Without a good history or photographs, it may not beWithout a good history or photographs, it may not be possible to ascertain the age of onset of apossible to ascertain the age of onset of a nevomelanocytic nevus <1.5 cm in diameter.nevomelanocytic nevus <1.5 cm in diameter.
  160. 160. BirthmarksBirthmarks
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