o Thickness - 0.07-12 mm
o Stratified sq. epithelium
o Different layers
Cells of the Epidermis
basal layer protect against UV irradiation
Racial differences are due to variation in
melanin production, not melanocyte numbers
Merkel cells sensation
One of the most common benign tumors of the skin
Often confused with malignancies
Seborrheic keratoses unusual before age 30
Most people develop at least one seborrheic
keratosis in their lifetime
Seborrheic keratoses are cosmetically bothersome,
but may also be subject to irritation and
Most often seen on the trunk
The size and surface appearance of the lesions
Most are 2 mm to 2.0 cm, although larger lesions
Lesions may be flat or raised
The surface may be smooth, velvety, or
Color and structure
The color of lesions is extremely variable,
Lesions tend to be sharply demarcated,
oval, and often oriented along skin
Most have a “stuck-on” appearance and
waxy texture. The surface tends to
crumble when picked.
Raised or pedunculated seborrheic
keratoses may be indistinguishable from
skin tags and compound melanocytic nevi.
Irritated seborrheic keratosis
When inflamed, SKs become slightly swollen and develop
an irregular, red flare in the surrounding skin.
Itching and erythema can then appear spontaneously in
other SKs that have not been manipulated and in areas
With continued inflammation, the SK loses most of its
normal characteristics and becomes a bright red, oozing
mass with a friable surface that itches intensely and
resembles an advanced melanoma or a pyogenic
Seborrheic keratosis vs. Melanoma
SKs can show many of the features of a
malignant melanoma, including an irregular
border and variable pigmentation.
The key differential diagnostic features are the
Melanomas have a smooth surface that varies in
elevation and in color, density, and shade.
SKs preserve a uniform appearance over their
Many SKs occur in sun-exposed areas.
Dermatosis papulosa nigra
Cryosurgery is effective for flat to
minimally raised lesions
Thicker lesions are best removed by
cautery and curettage under local
Hypopigmentation or hyperpigmentation
are possible side effects
Residual scarring is minimal. Applying
gentle pressure to the surrounding skin
often provides enough tension to allow for
easy curettage of lesions.
Moles (melanocytic naevi) as they are due to a
proliferation of melanocytes
Moles may be flat or protruding. They vary in
colour from pink to dark brown or black.
The number of moles a person has depends on
genetic factors and on sun exposure.
Melanocytic naevi may be present at birth
(congenital) but more usually begin to grow
during childhood although new ones can appear
at any age, sometimes in crops
Moles may darken following sun exposure
or during pregnancy.
During adulthood they often lose their
pigmentation, and they may even
disappear in old age.
Risk of melanoma
Malignant melanoma sometimes develops within
congenital melanocytic naevi.
The risk in a small or medium-sized mole is under
Melanoma is more likely in the giant naevi
(perhaps about 5% over a lifetime) especially in
those that lie across the spine; the cancer can
start in the skin or within the central nervous
system. It is then very difficult to detect and
Removal of moles
Although most moles are harmless and can be
safely left alone, moles may be treated under the
Possible malignancy: a mole that has bled, has
an unusual shape, is growing rapidly or changing
Nuisance moles: a mole that is irritated by
clothing, comb or razor.
Cosmetic reasons: the mole is unsightly.
scalpel or by electrosurgery. The wound heals to leave a
flat white mark, but sometimes the colour remains the
same as the original mole.
if the mole is a flat one or melanoma is suspected
Dermatofibroma is a common, benign,
The etiology is unknown.
Pontaneous benign neoplastic process Vs.
reactive hyperplasia in response to injury
These lesions occur more often in women
Most are asymptomatic, but itching and
tenderness may occur occasionally
Dermatofibromas discrete firm dermal papules, 3-
7 mm in diameter.
Most are dome shaped
Dermatofibromas typically flesh colored to pink
with a poorly defined rim of tan to brown
Larger ( >3cm) lesions can be worrisome and
may require a biopsy for definitive diagnosis
Dermatofibromas should be stable in size,
appearance, and color.
If they are not, they should be biopsied to
confirm their benign nature.
The lesion is fixed within the skin, but movable over the
underlying subcutaneous fat. On palpation, the lesion feels
like a firm button. Pinching a dome-shaped dermatofibroma
between two fingers causes the lesion to retract and dimple
below the level of surrounding skin.
Rarely, lesions may be blue to black in color as a result of
hemosiderin deposition, which may resemble melanoma.
The surface may be smooth and shiny to scaly or
Although dermatofibromas may arise on any cutaneous
surface, most are found randomly distributed on the
extremities. Lesions are usually solitary, however, multiple
lesions are not uncommon. Rarely, dermatofibromas occur
on the palms or the soles. Dermatofibromas should be
stable in size, appearance, and color
Dermatofibromas are benign skin tumors
that do not require treatment unless they
are symptomatic, repeatedly traumatized,
or cosmetically bothersome.
Surgical excision with primary closure is
the treatment of choice for symptomatic
If incompletely excised, the patient
should be warned of possible recurrence.
A pilar cyst is a firm, subcutaneous,
keratin-filled cyst originating from the
outer root sheath of the hair follicle.
Roughly 90% of pilar cysts are found on
the scalp, with the remaining 10%
occurring on the face, neck, back, and
The epithelium of the outer root sheath
undergoes a different form of
keratinization than cutaneous epithelium.
The surface is smooth and dome-shaped.
Pilar cysts may be difficult to distinguish from epidermal
cysts clinically, except by location.
Both present as a firm, subcutaneous nodules ranging
from 0.5 to 5.0 cm.
No central punctum is seen over a pilar cyst, as is found
over an epidermal cyst.
When dissected, a pilar cyst possesses a tough, white-gray
wall that is more resistant to tearing than the wall of an
The pilar cyst wall separates easily and cleanly from the
If a pilar cyst ruptures, the area becomes inflamed, red,
and tender and boggy on palpation.
Pilar cysts almost always develop after puberty.
The tendency to develop pilar cysts often has an
autosomal dominant inheritance.
Pilar cysts are multiple in 70% of patients who
Pilar cysts persist indefinitely and slowly grow to
a stable size unless they rupture.
Pilar cysts rupture less frequently than epidermal
cysts, presumably because the pilar cyst
possesses a thicker wall.
Rupture usually results from an external trauma.
A brisk foreign body inflammatory reaction
follows and can be quite painful and resembles a
Clinical findings pilar cyst
Large cysts may be cosmetically
Some cysts are so large and tender, they
may interfere with wearing hats and
Acute inflammation after rupture is often
misdiagnosed as infection.
Antibiotics are of little value in such cases.
Incision and drainage under local
anesthesia improve comfort and limit
Elective excision before rupture prevents
Pilar cysts are easily removed with excision under local
An incision is made over the cyst, exposing the cyst’s
glossy white external surface.
The cyst wall is freed easily from the surrounding
connective tissue by blunt dissection.
At this stage, smaller cysts may be expressed intact up
through the incision by steady, firm pressure on each side
of the incision.
The incised cyst wall is clamped, and through a
combination of gentle traction and pressure on each side of
the incision, the now smaller, partially emptied cyst is
delivered through the incision.
Larger cysts, which cannot be expressed in this manner,
should be incised and their contents removed by curettage.
Sutures may be needed to close the incision site.
Keratoacanthoma is a rapidly growing crateriform nodule
with a distinctive clinical appearance that is best regarded
as a low-grade squamous cell carcinoma. The peak
incidence of keratoacanthoma is between ages 50 and 70.
This tumor is rare before 40 years of age. Caucasians with
fair complexions are most often affected.
Chemical exposure and human papillomavirus have been
implicated as a cause in animal models, although their role
in humans is controversial. Historically, keratoacanthomas
have been regarded as benign regressing lesions, however,
they should be thought of as variants of squamous cell
carcinoma and treated as s
Clinical findings common features
A keratoacanthoma is a characteristic solitary
flesh-colored to red, crateriform nodule, usually
0.5 to 2.0 cm in diameter.
The lesion erupts rapidly and is often quite
A central keratotic plug or depression conceals a
deep keratinous cavity.
This plug or depression gives the nodule its
characteristic volcano-like shape.
The nodule is firm in texture, tender to palpation
Keratoacanthoma nearly always appears on sun-
Typical locations include the face, neck, dorsal
hands and sun exposed extremities.
It occurs on the legs more often in women.
Growth phases ka
Three growth phases are described:
1. Proliferative phase: a solitary papule
appears suddenly and then rapidly grows
to its maximum size over 2 to 4 weeks.
2. Mature phase: the lesion is stable in
size and appearance for weeks to months;
it may appear crateriform if the core has
been partially removed.
3. Resolving phase: the base becomes
indurated, the central core is expelled, and
the base resorbs, leaving a pitted scar.
This phase may last several months.
It is best to presume a diagnosis of
squamous cell carcinoma pending biopsy
results and clinical follow-up.
An excisional biopsy or shave removal
should be performed.
It is important to biopsy deep enough to
evaluate the dermis for possible invasion.
Treatment options include complete
excision with margins and
electrodesiccation and curettage.
Any of these options are curative in the
vast majority of cases.
An epidermal cyst is a firm, subcutaneous,
keratin-filled cyst originating from true
epidermis, most often from the hair follicle
Epidermal cysts are common, usually
solitary, and arise spontaneously.
They occur most commonly on the trunk,
postauricular fold and on the posterior
Potential to rupture
Cysts frequently develop in areas of
Most epidermal cysts arise from the
squamous epithelium of the hair follicle.
Unlike pilar cysts, the epidermal cyst wall
is fairly delicate and thus prone to rupture.
Rupture is followed by foreign body
reaction to keratin extruded into the
dermis and acute inflammation.
Such lesions appear to be infected.
However, cultures are usually sterile.
Typical findings/characteristic findings
Epidermal cysts are firm, dome-shaped,
pale yellow, cystic nodules ranging in size
from 0.5 to 5.0 cm in size.
Cysts are somewhat mobile but are
tethered to the overlying skin through a
small punctum that often appears as a
This punctum represents the follicle from
which the cyst developed.
These cysts may be flat or flush to the
surface of the skin or elevated well above
the surface. In either case, they are easily
Epidermal cysts that have not previously ruptured can be
excised easily and completely under local anesthesia.
Epidermal cysts on the face may rupture and lead to
Cosmetic considerations of elective surgical excision must
be weighed against scar formation resulting from rupture.
Such lesions are far more difficult to remove once they
Recurrent epidermal cysts that have previously ruptured
and scarred are best excised along with the surrounding
scar once the inflammation has subsided.
Asymptomatic epidermal cysts occurring elsewhere do not
Skin tags or achrocordons, are common, benign,
fleshy papules occurring in the skin folds.
They are uncommon before age 30 and common
Skin tags are more common in overweight
persons. Roughly 25% of adults have at least one
The majority of patients with skin tags have only
a few such lesions.
There may be a familial tendency toward multiple
Undisturbed lesions are usually asymptomatic.
Skin tags may become irritated by friction,
jewelry or clothing.
They may become tender and may bleed, when
traumatized, twisted, torn, or thrombosed.
Skin tags are skin-colored or slightly pigmented,
1 to 5 mm pedunculated papules.
They are typically not difficult to diagnose.
They may be flat or filiform, although most are
soft, fleshy, and pedunculated on a thin stalk.
The axillae are the most common location to find
Skin tags also occur on the neck, eyelids, as well
as in other intertriginous areas such as the
inframammary and inguinal creases.
The overwhelming majority of skin tags are
benign and have no internal disease association.
Asymptomatic skin tags do not require
Patients often request removal for
bleeding, tenderness or for cosmetic
Skin tags are best treated by scissor
excision with or without local anesthesia.
Electrocautery and cryosurgery can also
Many dermatologists feel that histologic
confirmation is usually not necessary, but
submission of all skin tags for histologic
review is a topic of debate
Syringomas are the most common tumor
of the intraepidermal eccrine sweat
These appendage tumors develop after
puberty and increase in number
throughout young adulthood.
Lesions are asymptomatic, stable in size
and appearance, and persistent.
The autosomal dominant inheritance of
multiple syringomas is well established.
Syringomas occur with increased
frequency in individuals with Down
syndrome or trisomy 21.
Syringomas are small, skin-colored to yellow, 1-
to 2-mm papules.
They are most commonly found on the lower
They also occur on the malar cheeks, axillae,
upper chest, abdomen, umbilicus, and vulva.
Papules are usually symmetrically distributed
Syringomas persist indefinitely and remain small.
They have no potential for malignancy.
They may resemble flat warts or sebaceous
Facial lesions are of cosmetic concern, and most
patients request removal of larger lesions.
The patient may be concerned that the lesions
Women seeking evaluation of vulvar lesions may
Syringomas may be removed for cosmetic
Electrodesiccation and curettage, laser
surgery, and trichloroacetic acid may be
used with variable success.
Sharp dissection or scissor excision of
lesions is easily performed under local
All of these procedures can lead to
scarring, so care and precision are
In some patients, syringomas are too
numerous to remove all lesions
Pyogenic granulomas are a benign
overgrowth of blood vessels. They present
as rapidly growing pinkish red nodules
which are friable and readily bleed. They
may follow trauma and are often found on
the fingers and lips. They are best excised
to exclude an amelanotic malignant
Campbell de Morgan spots
These are benign angiokeratomas that
appear as tiny pinpoint red papules,
especially on the trunk, and increase with
age. No treatment is required.
Swellings arising from the skin
Etiology : Smoking, Syphilis, Sepsis,
Sharp edge of the tooth, Spirits, Spices ---
the 6 S
Incidence: Occurs in 40 – 70 yrs of age
with male dominance
Gross feature: White hyperkeratotic patch
in the mucosa
Histology : hyperkeratosis over a
thickened acanthotic but orderly mucosal
* age = 40-70 yrs
* sex = males
* habits = tobacco ,alcohol ,use of chronic
* inf. = HPV-16
* others = ill fitting dentures
Actinic or solar keratosis
Etiology : Sun exposure (U.V) and
Incidence : in persons past middle life
Prognosis : SCC may develop
• Synonyms - solar keratosis, senile
• Age = >40
• Sex = male
• Occupation = outdoor works
• Race = fair skinned, blue eyes
• Genetics = xeroderma
Gross feature: White hyperkeratotic patch
in the mucosa
Histology : hyperkeratosis over a
thickened acanthotic but orderly mucosal
Gross feature: Lesions are less than 1 cm
in diameter; are tan brown, red or skin
colored; and have a rough, sandpaper like
Multiple lesions on the face and the backs
Histology : Building up of excess keratin,
cytological atypia and associated basal cell
A.k.a. carcinoma in situ and squamous
Etiology : Involve predominantly skin
unexposed to the sun (i.e., protected).
Role of HPV 16.
Incidence : Involves the genital region of
both men and women above the age of 35
Prognosis : May transform into SCC
Gross feature : Solitary, thickened, gray-
white, opaque plaque with shallow
ulceration and crusting
Histology : the epidermis shows
proliferation with numerous mitoses, some
BASAL CELL CARCINOMA BCC
Definition and etiology:
Basal cell carcinoma is a malignant
neoplasm arising from the basal cells of
Most basal cell carcinomas are caused by
sunlight-induced damage to the skin.
Basal cell carcinoma is the most frequent
malignancy in the United States,
with more than 750,000 new cases
reported annually. Although basal cell
almost never metastasizes, its malignant
nature is emphasized by the local
that it can cause.
As with other sun-induced neoplasms of
the skin, fair-complected
individuals and those with a lot of sunlight
exposure are most likely to develop
basal cell carcinoma.
Clinical features BCC
Clinically, there are four major types of basal cell carcinomas:
superficial, morpheaform, and pigmented.
Rarer types include cystic and keratotic carcinoma and
fibroepithelioma of Pinkus.
They are, of course, found most commonly on sun-exposed skin.
Nodular basal cell carcinomas, the most common type, appears
as a pearly semitranslucent papule or nodule that has a depressed
telangiectasia, and rolled waxy border. Crusting and ulceration
The most common location is on the face, particularly the nose.
Superficial basal cell carcinomas look quite different.
They are red, slightly scaling, slightly crusted, well-demarcated
eczematous-appearing patches that most commonly occur on the
Infiltrative or morpheaform basal cell carcinoma appears as an
atrophic, whitish, scarlike eroded or crusted plaque.
Pigmented basal cell carcinoma is a shiny brown, blue, or black
papule or nodule.
The differential diagnosis
of basal cell carcinoma depends on the
For nodular basal cell carcinoma, the
differential diagnosis includes ;
Sebaceous hyperplasia, fibrous papule of
the nose, nonpigmented nevus, and
carcinoma. Dermatitis, psoriasis, and
Bowen’s disease (squamous cell carcinoma
situ) appear similar to superficial basal cell
Seborrhoeic keratosis,pigmented nevus, and,
most important, malignant melanoma must be
ruled out in
the case of pigmented basal cell carcinoma.
For crusted nonhealing scarlike lesions,
the differential diagnosis is mainly between
basal cell and squamous cell carcinoma.
A skin biopsy, either shave, punch, or excision,
should be accomplished to confirm the diagnosis
of basal cell carcinoma.
The tumor is composed of a thickened
epidermis with invasive buds and lobules of
Curettage and electrodesiccation of the lesion or
excision are the most common surgical modalities
used to treat basal cell carcinoma.
Because of the locally destructive nature and
potential for recurrence of the disease, treatment
should be done by an experienced clinician who
can individualize the therapeutic modality
based on location of the lesion, histopathologic
type, size of the basal cell carcinoma, and its
primary or recurrent status.
Less commonly used treatments are radiation
therapy, cryosurgery, and topical chemotherapy.
A specialized surgical technique, Mohs’ surgery,
is indicated for recurrent basal cell carcinoma and
for primary tumors with a high risk of recurrence.
Basal cell carcinoma
Synonyms: basal cell epithelioma,
A malignancy arising from the epidermal
Etiology and Pathogenesis
Ionizing radiation: 10
Carcinogens: tar, oils
Chronic skin damage:
scars of trauma and
Other factors :
Age =>60 years
Gender = > men
Race= less in dark
Geography = high
Majority in the face
Line connecting the corners of the mouth
to the bottom of the ears
Lower part of the face, scalp and upper
part of the trunk
Initial basal cell carcinoma
crusted or scabbed
Cheek and nose
Nodular basal cell carcinoma
Pearly or waxy
Central dell or
Ulcerated basal cell carcinoma
Nasolabial fold,medial canthus
and about the ear
Crusts and granulation tissues
D.D: factitial ulcers
Pigemented basal cell carcinoma
Papular or nodular
Slate-blue to black
nevus, blue nevus,
BCC in scars
Fibroepithelioma= soft pink flesh coloured
or pale coloured nodules on the trunk
Metatypical= cannot differentiate b/w BCC
and SCC under the microscope
BCC in scars= ulcer not a telangiectatic
nodule. Recurrent BCC and a scar
0.0028 to 0.1%
Large ulcerated basal cell carcinomas in
the mid face
SQUAMOUS CELL CARCINOMA
Definition and etiology:
Squamous cell carcinoma is a malignant
neoplasm of keratinocytes that is locally
invasive and has the potential to
Ultraviolet radiation, x-rays,
papillomavirus infection, and chemical
carcinogens such as soot and arsenic
cause squamous cell carcinoma.
Clinical features SCC
Squamous cell carcinoma is the second most
common skin cancer in the United States, with
more than 100,000 new cases diagnosed
As with other sunlight-induced skin cancers, the
frequency of squamous cell carcinoma is
increased in those who are fair complected or
engage in many outdoor activities.
The history of a bleeding growth or ulcer should
arouse suspicion of squamous cell carcinoma.
Squamous cell carcinoma most often arises in
It also develops on the mucous membranes and
in areas of chronic injury such as burn scars,
chronic radiodermatitic lesions, chronic draining
sinuses, and areas of erosive discoid lupus
The examination reveals a hard papule or
nodule that is erythematous to flesh-
colored, smooth, scaling, and crusted.
Squamous cell carcinoma in situ(Bowen’s
disease) has a different appearance,
being a well-demarcated, slightly scaling,
slightly crusted, eczematous-appearing
The differential diagnosis of squamous cell
keratoacanthoma, hypertrophic actinic
keratosis, wart, basal cell carcinoma, and
seborrheic keratosis. Any lesion that is
crusted or ulcerated should be suspected
of being squamous cell carcinoma, and
biopsy must be done.
This reveals a hyperkeratotic thickened
epidermis containing atypical
keratinocytes that invade the dermis.
Treatment SCC Squamous cell carcinoma should be totally
Follow-up to monitor for local recurrence as well
as metastases is required.
The squamous cell carcinomas most likely to
metastasize are those that are large or
histologically poorly differentiated, have deep
invasion, or occur in damaged skin or the mucous
membranes of the lips, glans penis, and vulva.
Metastasis is generally to the regional lymph
nodes, and careful attention should be given to
examining them for
Squamous cell carcinoma
Primary cutaneous SCC is a malignant
neoplasm of keratinising epidermal cells
Basal: squamous =5:1 to 10:1
Occupation= outdoor workers
Genetics = xeroderma
Geography= equator or high
Etiology and pathogenesis
Chronic degenerative and inflammatory
Oncogenic Viruses: HPV
Genetic disorders: xeroderma
Personal habits: alcohol and tobacco
indistinct clinical picture
Hard exophytic,inflamed nodule
Ulcerated and necrotic
Unfavourable signs: rapid growth,induration,
A squamous cell carcinoma which develops
in a chronic scar such as along standing
ulcer or osteomyelitis sinus.
Slow growth – relatively avascular
Absence of secondary deposits in regional
Extent of the tumor
epidermis + part of dermis
whole thickness of the skin