Benign Elanocytic Lesions | COMMON ACQUIRED MELANOCYTIC NEVI

COMMON ACQUIRED MELANOCYTIC NEVI
Nevocellular nevus / “Mole”

▪ A benign cluster of melanocytic naevus cells
arising as a result of
proliferation of melanocytes at the dermal–epidermal junction.

▪ the melanocytes proliferate for some time
but then cease proliferation and differentiate
and come to resemble cells of neural or fibroblast lineage.

CLASSIFICATION
1. Junctional
2. Compound
3. Dermal
4. Naevi of unusual sites (palms/soles/nail unit)
5. Spitz naevi
6. Blue naevi
7. Halo naevus 8. Meyerson naevus 9. Naevus en cockade
8. Atypical naevi

Junctional naevus
Junctional nevus–
dark brown macule
with lighter brown rim.
Single, nested melanocytes at DEJ and lower spinous layer.

Compound naevus
Compound nevus –
light to medium brown
papule.
Single and nested melanocytes at the DEJ, papillary dermis and/or reticular dermis.

Intradermal naevus
Intradermal nevus –
soft light pink papule.
Single and nested melanocytes confined to the reticular dermis.

Natural history
▪ develop through childhood
▪ continue to erupt in adult life
▪ After 45 yrs of age, naevi involute
(so elderly usually have very few.)
* new naevi developing in later life should be viewed with suspicion

Junctional naevus
Dermoscopically
a uniform pigment network.

Compound naevus
Dermoscopically
Exophytic papillary structures (blue circle)
and
reticular pattern (square).

Intradermal naevus
Dermoscopically
Focal globular-like structures
whitish structureless areas,
and fine comma vessels.

▪ Relation to melanoma:
▪ Significant proportion of melanoma patients report the prior presence of a longstanding melanocytic naevus
▪ Histolog.: 1/3 of melanomas have naevus remnants
▪ Increased number of melanocytic naevi correlates with increased melanoma risk

▪ Compound and dermal nevi typically show zonation with depth (maturation) in the dermis.
▪ Type A cells: Large epithelioid melanocytes in the superficial dermis
▪ Type B cells: melanocytes tend to have less cytoplasm with descent into the reticular dermis
▪ Type C cells: become fusiform at the base of a lesion

▪ Type A cells: Large epithelioid melanocytes in the superficial
dermis

▪ Type B cells: melanocytes tend to have less cytoplasm with descent
into the reticular dermis

▪ Type C cells: become fusiform at the base of a lesion

▪ The full range of cytologic appearances from type A to type C melanocytes is seen only in a minority of
nevi.

differential diagnosis
1. Seborrhoeic keratosis
– In older adults
– ‘stuck on’ appearance
– Bulk above the normal skin contour
– More grey brown
– Surface: dull/ pitted/ tendency to crumble

2. Early malignant melanoma
▪ * very rapid growth / tenderness
: not features of malignant
change

3. Dermatofibroma
▪ Very firm consistency
▪ ‘dimpling’ on lateral compression
▪ Central white patch on dermoscopy
▪ If the skin over the dermatofibroma is squeezed a dimple forms which indicates tethering of the
skin to the underlying fibrous tissue (dimple sign).

4. Neurofibroma
5. Fibroepithelial poyps

Management:
Indications for removing melanocytic nevi:
▪ A changing lesion
▪ Atypical clinical appearance (suspicious of melanoma)
▪ Repeated irritation
▪ Cosmetic concerns

Management:
▪ If excised, always send for pathological examination.

Management:
Avoid partial removal
Residual deep dermal naevus cells may proliferate after excision
Pathologic picture similar to early melanoma
‘Pseudomelanoma’
‘Traumatically activated nevus’

Balloon cell naevus
▪ Subtype of compound melanocytic naevus
▪ Cells with a high volume of foamy cytoplasm (‘balloon’)
▪ Not premalignant

Naevi of nail matrix
▪ Uniformly pigmented brown longitudnal bands (melanonychia striata)
▪ Regular & distinct margins
▪ D/D: early subungal melanoma

▪ Subungual melanoma often starts as melanonychia.
Over weeks to months, the pigment band:
▪ Becomes wider, especially at its proximal end (cuticle)
▪ Becomes more irregular in pigmentation(light brown, dark brown)
▪ Extends to involve the adjacent nail fold (Hutchinson sign)
▪ May develop a nodule, ulcer or bleed
▪ May cause nail dystrophy

Nail matrix naevi

▪ Whenever dermatoscopy is not accessible, criteria to help perform the biopsy are:
– A single nail affected.
– Brown or Black band > 3 mm.
– periungueal pigment effusion – Hutchinson's Sign.

Melanocytic nevi of genital and
flexural skin

Melanocytic nevi of genital and flexural skin
▪ Nevi in “special sites”, including genitalia, sometimes have atypical
histologic changes, making distinction from melanoma difficult.

▪ premenopausal women (ages 14 to 40 years) : vulvar lesions.
▪ larger in size than non-genital nevi,
▪ fairly regular borders
▪ Complex mahogany color (an admixture of tan, brown and red).

Pathology
▪ characterized by an overall symmetry
▪ well circumscribed
▪ absence of lateral extension of intraepidermal melanocytic components beyond the dermal nevus
elements
* Architectural and cytologic features similar to atypical melanocytic nevi.

MELANOCYTIC NEVUS OF ACRAL SKIN

Macular or only slightly elevated.
Uniform brown or dark brown color,
Often have linear striations

▪ Dermoscopy:

▪ MANIACS
Melanocytic Naevus with Intrepidermal Ascent of Cells

SPITZ NAEVUS
Spindle & epitheloid cell naevus / Juvenile melanoma

SPITZ NAEVUS
well-circumscribed, dome-shaped papules
or nodules
varying in color from pink to tan to dark
brown
color is homogeneous and the
margins are well defined.

SPITZ NAEVUS
▪ Children ( 50% cases < 14 yrs age )
▪ Rapid growth over 3-6 months, then static for years
▪ Face (esp. cheeks)
▪ Bleeds easy

SPITZ NAEVUS
▪ Spitzoid lesions are composed of varying proportions of spindled and epithelioid cells that display a
characteristic cytomorphology that is the common thread between the classic Spitz nevus and all its
variants.

SPITZ NAEVUS
▪ cells are large, contain abundant eosinophilic cytoplasm
▪ have nuclei with smooth nuclear membranes, delicate chromatin and prominent central nucleoli.
▪ Within a given lesion, spitzoid cells are generally uniform in size and appearance.

SPITZ NAEVUS
1. Classic : compound (most common), junctional or intradermal
2. Agminated (grouped) Spitz nevi
3. Pigmented spindle cell nevus of Reed
4. Desmoplastic
5. Atypical Spitz nevi
6. Malignant or metastasizing Spitz nevi

SPITZ NAEVUS
Pigmented spindle cell nevus of Reed
More deeply pigmented variant
Thighs of young females
Dark brown / black nodules

Dermoscopy :
▪ ‘STARBUST’ APPEARANCE

▪ Predominantly junctional melanocytic proliferation
▪ well-defined margins, symmetry.
▪ Several nests have a vertical configuration.

▪ Several nests have a vertical
configuration.
▪ Melanocytes are spindle-shaped .

SPITZ NAEVUS
Desmoplastic
Adults
Firm/ pink or red/ raised nodules
Little or no clinically visible melanocytic
pigmentation

SPITZ NAEVUS
▪ proliferation of large polygonal to
spindled melanocytes
▪ within a fibrotic dermis
▪ often with no junctional component

SPITZ NAEVUS
▪ infiltrate as single cells
between the thickened dermal
collagen bundles

SPITZ NAEVUS
Agminate spitz naevi
varying numbers
of raised nevi
in a localized or segmental distribution,
arising in otherwise clinically normal skin

SPITZ NAEVUS
Atypical
lesions demonstrating one or more features that deviate from conventional Spitz nevi:
▪ large size (e.g. >1 cm in diameter) / ulceration / asymmetry
▪ deep involvement of the dermis or subcutis;
▪ Dermal mitoses (>2–3 mitoses/mm2)
▪ Significant pagetoid spread;
▪ prominent confluence and high density of melanocytes in the dermis
▪ lack of maturation.

SPITZ NAEVUS
Atypical
relative lack of symmetry.

Asymmetry
Variation in the size,
shape, orientation, spacing
or cohesion of nests
Pagetoid spread

Cytologic atypia:
▪ Pleomorphism
▪ Variation in chromatin
pattern
▪ Nucleomegaly
▪ Variation in nucleoli

Spitz vs Atypical spitz vs Spitzoid melanoma

SPITZ NAEVUS
Treatment
▪ Histological evaluation of the entire lesion is recommended.
▪ Local excision with narrow margin of 1-2 mm for confirming diagnosis
▪ Recurrence rate after complete excision : 7-16%

SPITZ NAEVUS
Treatment
▪ In presence of atypical features
▪ Margin of excision same as for melanoma
Tumors<2mm : 1 cm margin
Tumors > 2mm : 2cms or more margins

SPITZ NAEVUS
Treatment
▪ Atypical lesions : follow up 6 monthly
▪ Sentinel node biopsy : case to case basis
no survival benefit

BLUE NAEVUS
Blue naevus of Jadassohn-Tieche/ Blue neuronevus / Dermal melanocytoma

BLUE NAEVUS
▪ Comprises of aberrant collections of
pigment-producing benign melanocytes,
in the dermis rather than at the dermoepidermal junction
(as in common acquired naevi).

BLUE NAEVUS
Pathogenesis
▪ Blue color : due to TYNDALL PHENOMENON
▪ Somatic mutations In GNA 11 & GNAQ (65-75%)

BLUE NAEVUS
Childhood/ adolescence
well-circumscribed, dome-shaped solitary
papule
blue, blue–gray or blue–black
face and scalp/ dorsal aspect of the hands
and feet

BLUE NAEVUS
Variants
1. Cellular blue naevus
2. Epitheloid blue naevus
3. Pigmented epitheloid melanocytoma
4. Malignant blue naevi

BLUE NAEVUS
Cellular blue nevi
▪ blue to blue–gray or black nodules or plaques,
▪ generally 1 to 3 cm in diameter but sometimes larger .
▪ The most common sites are the buttocks, sacrococcygeal area.

BLUE NAEVUS
Epitheloid blue nevi
▪ Feature of CARNEY COMPLEX

BLUE NAEVUS
Pigmented epitheloid melanocytoma
▪ Controversial
▪ Unifies Epitheloid blue naevi & Pigment synthesizing melanoma

BLUE NAEVUS
Malignant blue nevi
▪ Cutaneous melnnoma arising in or having features of blue naevus.
▪ Multinodular/ plaque like
▪ Scalp (most common)

BLUE NAEVUS
D/D
▪ Traumatic tattoo
▪ Vascular lesions (venous lake/ angiokeratoma)
▪ Atypical naevus
▪ Melanoma
▪ dermatofibroma

BLUE NAEVUS
Treatment
▪ <1 cm in diameter,
▪ clinically stable,
▪ do not have atypical features
▪ located in a typical anatomic site
do not
require removal.

BLUE NAEVUS
Treatment
▪ lesions that appear de novo,
▪ are multinodular or plaque-like,
▪ have undergone change
▪ Atypical cellular blue nevi and pigmented epithelioid melanocytomas should be resected completely (risk
for malignant transformation)
Histological evaluation

HALO NAEVUS
Sutton’s naevus/ Leukoderma acquisitum centrifugum / Perinevoid vitiligo

HALO NAEVUS / SUTTON’S NAEVUS
▪ A melanocytic naevus surrounded by a depigmented
halo of otherwise normal skin.

HALO NAEVUS
under the age of 20
a central melanocytic nevus component
well-circumscribed annulus of hypo- or
depigmented
Skin
Erythema occasionally precedes

▪ upper back
▪ 50% of affected individuals have two or more halo nevi
▪ usually regresses over months to years, leaving a white macule
▪ Complete repigmentation of the skin is seen in the vast majority

Pathogenesis
▪ an immune response against antigenically altered nevus cells associated with tumor progression
(dysplasia)

Pathology
▪ Variants of compound melanocytic naevi
▪ At the time of appearance of the halo they show a very striking lymphocytic infi ltrate admixed with the
intradermal naevus cells.
▪ The use of DOPA stains will reveal a loss of epidermal melanocytes in the halo area.

Management
▪ personal or family history of cutaneous melanoma, atypical nevi and vitiligo.
▪ Inspected for features of an atypical melanocytic nevus or melanoma

Management
▪ If no atypical features, the patient should be followed with periodic skin examinations.
▪ Clinically atypical halo nevi should be examined histologically.

MEYERSON’S NAEVUS
▪ a melanocytic naevus that has developed
an associated infl ammatory reaction,
which looks like eczema.

MEYERSON’S NAEVUS
melanocytic naevi
associated epidermal scaling
a halo of infl ammation.
may be pruritic

MEYERSON’S NAEVUS
Pathology
▪ A banal, usually compound, naevus with associated spongiotic dermatitis in the overlying dermis.

MEYERSON’S NAEVUS
Treatment.
▪ 1–2 weeks of moderately potent topical steroid
▪ secondary eczematous reaction settles
▪ Then , dermoscopy to ensure that the underlying naevus is benign

Cockade naevus
Naevus en cocarde

MEYERSON’S NAEVUS
▪ rare variant of the pigmented naevus
▪ resemblance to a rosette.
▪ Young patients

MEYERSON’S NAEVUS
multiple, target-like naevi
concentric circles of increased melanin
pigmentation.
central lesion in all cases is a junctional
naevus

ATYPICAL (DYSPLASTIC) MELANOCYTIC NEVUS
Clark’s nevus/ Nevus with architectural disorder / B-K mole /
The mole of FAMM (familial atypical mole and melanoma syndrome)

▪ Elder
▪ A controversial clinical designation for :
– Various naevi that have morphological changes (asymmetry / irregular
borders / colour variation)
– Naevi with architectural changes and / or cytological atypia.

1. Nevi with atypical clinical features
2. Nevi with abnormal histopathological features
3. Nevi with both abnormal clinical and histopathological features
4. Nevi with histopathological features that are equivocal or of unknown significance

A melanocytic naevus,
– which is 5 mm or larger in diameter,
– with an irregular or diffuse edge
– variable or mottled pigmentation
* Although there are histological correlates, the diagnosis is clinical.

Natural history
▪ The naural history of benign acquired naevi
▪ Proliferation of melanocytes, until naevus reaches upto 5mm diameter
▪ Then proliferation at DEJ ceases
▪ The naevus cells migrate down into dermis

Natural history
▪ Subsequently clinical senescence occurs
▪ Resulting in developent of compound naevus
▪ finally a cellular dermal naevus

Natural history
▪ The natural history of an atypical naevi
▪ Melanocyte proliferation continues
▪ Naevus continues to grow in size (beyond the usual size)
▪ Junctional proliferative component may show
some features similar to early melanoma

Natural history
▪ Results in irregularity of shape & color clinically
▪ Majority : Minority:
▪ Proliferation cease eventually continue to grow
Compound / dermal naevus May evolve into a Melanoma

‘SKIN AT RISK’
1
2
3

Data from literature
▪ 1. Irrespective of histology,
Melanoma risk is directly related to the numbers of ordinary naevi
+
Presence & number of atypical naevi

▪ 2. very poor correlation between,
Clinically atypical melanocytic naevi
&
Histologically atypical melanocytic naevi

▪ 3. Almost no data showing relationship between,
Histologically atypical melanocytic naevi
&
Increased Melanoma risk

Incidence & epidemiology
▪ White skinned
▪ ~ 10%
▪ Sweden
▪ FAMMM ( Familial Atypical Multiple Mole Melanoma Syndrome)
▪ Sporadic

Gross morphological features
1. Asymmetry
▪ Lack mirror-image symmetry
▪ Greater asymmetry: greater chance of atypicality

2. Size
▪ Greater size: greater chance of atypicality

3. Borders
▪ Irregular/ ill-defined
▪ Not notched / scalloped borders of melanoma

▪ 4. Coloration
▪ Irregularity of pigmentation
▪ 2-3 shades of brown (tan / brown / dark brown)

▪ Trunk > scalp > doubly covered areas (breasts / bathing trunk area)
▪ 1 – 100 in number

Pathology
▪ Scanning (20x) magnification
▪ – Shoulder
▪ – Stromal response with fibrosis and inflammation

Pathology
▪ Architectural disorder:
▪ – Circumscription: Junctional component nested at both edges vs. single-cell in at least one edge
▪ – Symmetrical: Good overall symmetry regarding edges, size of junctional nests, and stromal response
▪ – Cohesiveness of nests: >50% of nests cohesive
▪ – Pagetoid spread: prominent, at periphery
▪ – Confluent growth: in >50% of the junctional melanocytic proliferation, either as ridging of melanocytic nests or as
contiguous single cells
▪ – Single cell proliferation: Junctional melanocytes arranged as single cells in more than 20% of the lesion

Pathology
▪ Cytologic atypia
▪ – Nuclear shape and staining round-oval & euchromatic
▪ – Nuclear size > basal-layer keratinocyte nuclei
▪ – Nucleoli prominent > 50% of cells
▪ – Cell diameter >2x basal-layer keratinocyte nuclei

▪ shouldering (S), or extension of
the junctional component
beyond the dermal nests of
melanocytes (D).
▪ Rete ridges are irregular and
distorted with bridging (B)
▪ Eosinophilic fibrosis (arrows).
▪ Scattered lymphocytic infiltrate
is often present (*)

Two histologic features of architectural disorder include:
1. concentric eosinophilic fibrosis (E), in which fibrosis encircles a rete peg;
2. lamellar fibroplasia (L), in which the fibrosis is confined to the tip of the rete peg with stacks of collagen fibers.
Nests of melanocytes in the DEJ
demonstrate random cytologic
atypia (arrows).

▪ Cytological atypia in a dysplastic naevus is generally random and patchy, with atypical cells punctuating a
background of cells with minimal or no atypia.
▪ The presence of a monotonous population of severely atypical cells (in one region, or throughout the
lesion) is worrying for melanoma.

D/D
1. Melanocytic proliferations:
▪ Common acquired naevi/ small congenital naevi/ cutaneous melanoma
2. Keratinocytic lesions
▪ Pigmented seborrhoeic keratosis/ solar lentigines/ pigmented actinic keratosis/ Basal cell carcinoma

Treatment
▪ All patients diagnosed with 1 or more atypical mole (AM) should undergo a complete cutaneous
examination.
▪ self-examination to detect changes in existing moles and to recognize clinical features of melanomas.
▪ baseline and serial color photograph

Treatment
▪ the prophylactic removal of all atypical moles does not prevent the development of melanoma and is not
recommended.
▪ Regardless of the risk group, any pigmented lesion suspicious for melanoma and any persistently and
significantly changing lesion should,, be excised completely with approximately 2 mm margins for
histopathologic examination to exclude in situ melanoma.
▪ Such naevi should NEVER be punch biopsied or an incisional biopsy taken, as sampling error may cause
an early melanoma to be missed.

Treatment
▪ FAMMM ( Familial Atypical Multiple Mole Melanoma Syndrome)
▪ the phenotype is a marker of risk and that risk cannot be removed by removal of the naevi.
▪ Such patients must be counselled about avoidance of sunburn for themselves and their children.
▪ They should be taught how to self examine with the aid of images
▪ a short period of follow-up

Benign Elanocytic Lesions | COMMON ACQUIRED MELANOCYTIC NEVI

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