Melanocytic naevus

1. DR .YUGANDAR

2.  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.

3.  Epidermal nevi
 Melanocytic nevi
 Dermal & Subcutaneous nevi

4. Melanocytic nevi
 Cong. Melanocytic nevi
 Acquired Melanocytic nevi
 Dermal MN
 Clinically atypical nevi
 Special variants of acquired nevi

5.  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.

6.  Present at birth
 Greater malignant Potential
 Larger size
 Nevus cells have deeper penetration around
skin appendages, nerves and blood vessels

8.  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

10.  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

11.  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

12.  As they mature, they often develop
thickness, and become elevated, although
Prominent terminal hairs often form,
especially after puberty.

13.  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

14.  Common over scalp,
 skin coloured plaque
 Convoluted surface

15.  Closely set brown to black plaques forming
clusters
 Usually intradermal
 Could be follicle or eccrine centred

16.  Multiple nevi of head, neck, post midline
tumors ( Leptomeningeal melanocytosis)
 Epilepsy, MR, Inc ICT symptoms
 Other spinal dysraphism, Club foot,
Lipoma, vascular nevi

17.  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

18.  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

19.  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

20. •single row/ sheets/ combinations
i.e. INDIAN FILE APPERANCE
•nevus cells in reticular dermis

21.  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

22.  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

23.  Q switched Ruby laser
 Dermabrasion
 Pulsed Co2 laser
 Use of artificial dermis
 Fresh autologous cultured epithelium Under

24.  Defects in development of Epidermal
melanocytes
 Depend on melanocytic distribution in
skin divide
 Junctional N
 Compound N
 Intradermal N

25.  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

26.  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

27.  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

28. • Nests of nevus
•Decrease in size & melanin
content of nevus cells

29.  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

30.  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

31.  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

32.  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

33.  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

35.  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

36.  Diametre > 7cm
 Irregular edge
 Variable color
 Inflammation
 Bleeding
 Crusting
 Oozing
 Risk of melanoma in AMN

37.  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

38.  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

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

40.  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

41. Thank You Very Much for Your Kind
Attention