DR .YUGANDAR

The term Naevus has been used to describe a

large variety of clinically dissimilar

lesions,often leads considerable confusion.

They usually present at birth or early

childhood.

Due to Genetic mosaicism.

Epidermal nevi

Melanocytic nevi

Dermal & Subcutaneous nevi

Melanocytic nevi

Cong. Melanocytic nevi

Acquired Melanocytic nevi

Dermal MN

Clinically atypical nevi

Special variants of acquired nevi

Synonyms like cellular nevi or

Pigmented nevi are best avoided, as not

all melanocytic nevi are pigmented ,nor

does the term cellular nevi define cell

type.

Present at birth

Greater malignant Potential

Larger size

Nevus cells have deeper penetration around

skin appendages, nerves and blood vessels

Small-sized congenital nevocytic nevus is

defined as having a diameter less than

2 cm.

Medium-sized congenital nevocytic nevus is

defined as having a diameter more than

2 cm but less than 20 cm.

Giant congenital melanocytic nevus  is

defined by one or more large, darkly

pigmented and sometimes hairy patches

Growth of cong. Nevi is very rapid and

disproportionate to the growth of particular

body area affected in first 6 months

In adults nevus remains static unless there is

infection ,trauma, development of

malignancy

Tardive nevi : early onset nevi, seen in first

2 yrs of birth.Less than 10mm size

The congenital melanocytic nevus appears as a

circumscribed, light brown to black patch or plaque,

potentially very heterogeneous in consistency, covering

any size surface area and any part of the body.

As compared with a melanocytic nevus congenital

melanocytic nevi are usually larger in diameter and may

have excess terminal Hair,condition called

hypertrichosis.

Giant variety chances are 0.002% of Births

As they mature, they often develop

thickness, and become elevated,

although Prominent terminal hairs

often form, especially after puberty.

Nevi become larger,darker and more rugose

as child grows

Finally develop warty, nodular surface

Certain other varieties

Cerebriform Cong Nevus

Spotted grouped pigmented nevus

Neurocutaneous melanocytosis

Common over scalp,

skin coloured plaque

Convoluted surface

Closely set brown to black plaques

forming clusters

Usually intradermal

Could be follicle or eccrine centred

Multiple nevi of head, neck, post

midline tumors ( Leptomeningeal

melanocytosis)

Epilepsy, MR, Inc ICT symptoms

Other spinal dysraphism, Club foot,

Lipoma, vascular nevi

Carney complex : Primary adrenocortical

disease, Lentigines, Blue nevi, Neuro

endocrine disorders

NAME: Nevi, atrial myxoma, myxoid

neurofibromata and Ephelides

LAMB : Lentigines,atrial myxoma,

mucocutaneous myxoma, Blue nevi

Depend on age,size of lesion

May be junctional, compound or

intradermal

At birth in first week – junctional

( hyperplasia seen in both epidermis

and adnexal area

Presence of nevus cells in reticular dermis

Extension of nevus cells in colleagen

bundles as single row/ sheets/ combinations

i.e. INDIAN FILE APPERANCE

Higher CONCENTRATIONS OF CELLS

around blood vessels,nerves and adnexal

structures

S100 protien by immunohistochemistry in

deep periadnexal structures

•single row/ sheets/ combinations

i.e. INDIAN FILE APPERANCE

•nevus cells in reticular dermis

Risk of melanoma in caucasians 4.5-10%

MC from large CMN than Medius and smal

size CMN

Other tumors with CMN

Neurosarcoma

Rhabdomyosarcoma

Liposarcoma

Spindle cell sarcoma

Surgical excision of nevi performed as early as 3

weeks of birth

Others considered ideal time 10 to 14 months

Serial excision with use of tissue expanders and

grafting choice of therapy

Multiple medium size removed around puberty

Q switched Ruby laser

Dermabrasion

Pulsed Co2 laser

Use of artificial dermis

Fresh autologous cultured epithelium Under

trial

Defects in development of Epidermal

melanocytes

Depend on melanocytic distribution in

skin divide

Junctional N

Compound N

Intradermal N

Ackerman described it as Neoplasm b/c

they formed after Melanocytes achieved

maturity

With age, progressive maturation a/w

decrease in pigmentation

Most nevi become intradermal by early

adult life

Nevi on palms,soles and genitalia

remains junctional for long periods

15 to 40 %

Rarely present at birth

Appear in early childhood,

Progressively increase in number

Avg 15 in male, 20 to 29 in female

Rare beyond eighth decade

Formation of Nests of nevus cells in EpiDermis

Presence of Junctional activity in Junctional &

Compound types

Decrease in size & melanin content of nevus

cells as dermis downwards i.e. Process of

maturation

Formation of multinucleated giant cells

Mucinous,fibrosis,fatty change in regressive

stage

• Nests of nevus

•Decrease in size & melanin content of nevus cells

Junctional cells express both s100 &

melanoma associated antigens NK1/c-

3 ,HMB-45

Intraderma cells express only s100 antigens

In Loose nests nevus cells may demonstrate

Dendritic processes,In compact nest no

processes

Nevus cells-Upper dermis more

pigmented,cuboidal,abundant cytoplasm &

round nucleus i.e. Type A cells/epithelioid

In Mid dermis cells smaller,rounded,sparse

melanin i.e. Type B cell or Lypmoid cells

In Lower dermis Cells spindle shaped

resembling fibroblasts and schwann

cells,melanin absent i.e. Neuroid /type C

cells

J.Nevus: flat pigmented macule 3mm to 1cm

Colour varies from tan to brown – black

Skin surface markings preserved over nevus

90% of acquired nevi in children are J.N

J.N differentiated from freckles (s/o sun exposed

areas, fade on protection)

Lentigo simplex by HP examination

Compound Nevus: slightly raised circular

plaques

Pigment varies from brown to black

Centre being darker than periphery

Well established nevi often contain coarse

hair in centre

Irregular contour, variable color, irregular

perinevoid halo – risk of malignancy

Intradermal nevi: elderly adults

Difficult identify from compound nevi

Two variants

First seen after adolescence,dome

shaped,smooth surface over face.

Second seen inn adults sessile/soft

wrinkled sac seen over flexures

K/a cholinestrase nevus b/c of enzymes in

nevus

Melanomas arising from melanocytice

nevus better prognosis.

80% cases have sup. Spreading type

Junctional nevi got greater malignancy

potential

Acral lentiginous melanoma MC in asians

IL-1alfa,IL-1Beta,IL-6 protective role

Diametre > 7cm

Irregular edge

Variable color

Inflammation

Bleeding

Crusting

Oozing

Risk of melanoma in AMN

Removal by Esthetic prolems only

J.N over soles,palms,genitalis greater risk of

malignancy

Nevi at site of friction

Suddenly increase in size with pain indication

of removal

Inflamed nevi often excised

Incomplete excision- proliferation of remaining

tissue resembles melanoma: Psuedomelanoma

Similar to Melanocytic nevi Often observed on opposing eyelids

to form round shape when closed Indicates development of nevi b/w

2&6th month of fetal life Nevi : Caruncle,Limbal area,Eyeball. One conjuctival nevi transformed to

malignant melanoma

An active junctional nevus in the matrix gives rise to a single dark black band on the undersurface.

Rare,clinically compound or intradermal

Differing by collections of clear cells

Common in first three decades

Varying amount melanin in epi & Dermis

Balloon cells:single or groups,abundant

cytoplasm,small central nucleus. few multi

nucl.

DD: balloon cell melanoma,clear cell

hidradenoma,intradermal nevi

Thank You Very Much for Your Kind

Attention