Intradermal Nevous

ACQUIRED MELANOCYTIC NEVUS (MOLE) a benign, localized proliferation of nevus cells (originated from the neural crest)………..their ability to produce melanin These melanocytic cells migrate to the epidermis during development lesions may first appear shortly after birth. the most common of all human "tumors Intraoral lesions occur but are not common

several clinical stages which tend to correlate with specific histopathologic features. The earliest presentation microscopically as a junctional nevus A sharply demarcated, brown or black macule <6 mm in diameter this lesional appearance may persist into adulthood

compound nevus more often the nevus cells proliferate over a period of years to produce a slightly elevated, soft papule with a relatively smooth surface The degree of pigmentation becomes less most lesions appear brown or tan

intradermal nevus the nevus usually remains less than 6 mm in diameter As time passes…….. ……….loss of pigmentation the surface may become somewhat papillomatous hairs may be seen growing from the center the nevus usually remains less than 6 mm in diameter

Origin of nevus cells……. histopathologic Features a benign, unencapsulated proliferation of small, ovoid cells ( nevus cells)……. tend to be organized into small, round aggregates (theques). Origin of nevus cells……. from cells that migrate from the neural crest to the epi. and submucosa or from altered resident melanocytes

The lesional cells have small, uniform nuclei and a moderate amount of eosinophilic cytoplasm, with indistinct cell boundaries lack the dendritic processes A characteristic microscopic feature: that the superficial nevus cells tend to be organized into small, round aggregates (theques).

classified histopathologically according to their stage of development

Zones of differentiation often are seen throughout the lesion. type A: The superficial cells ………larger and epithelioid, with abundant cytoplasm, frequent intracellular melanin, and a tendency to cluster into theques

type B: Nevus cells of the middle portion of the lesion…… type B: Nevus cells of the middle portion of the lesion…….. less cytoplasm, are seldom pigmented, and appear much like lymphocytes

type C: Deeper nevus cells appear elongated and spindle shaped, much like Schwann cells or fibroblasts

1 1-Theque 2-Hair Follicle 2

1-Theque 1

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