Slide 135.Intradermal nevus, Skin

A. Brief Descriptions

  1. Congenital or acquired.

  2. Tan to brown, uniformly pigmented, small solid lesion of flat to elevated skin.

B. Gross Findings

  1. Papillary, pedunculated, dome shaped or flat, with or without hairs, brown or little darker than surrounding skin.

C. Micro Findings

  1. Small nests or bundles of nevus cells in dermis with thinned overlying epidermis.

  2. Nevus cells: (no necessarity to differentiate these cells described below).

  3. Cuboidal cells with regular, spheroid, moderately hyperchromatic nuclei.

    • Upper: larger cells (type A) with some multinucleated giant melanocytes.

    • Middle: smaller cells (type B) like lymphocytes.

    • Lower: spindle shaped (type C) in neuroid bundles (presumed schwannian derivation)

  4. No cellular atypia nor junctional activity.

    • Junctional activity: melanocytes proliferation or dropping off restricted to basal portion.

D. Others

  1. Melanocytes:

    • Neuroectodermal derived cells, located in the basal layer of skin, skin adnexae, & mucosal membranes.

    • Produce melanin & transfer through cytocrinia to adjacent epithelial cells.

    • Stains: silver, DOPA, S-100, vimentin.

    • Remove melanin pigments by potassium permanganate.

E. References

  1. Pathologic Basis of Disease. Ch27. p.1174-1176.



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Fig. 135-7 (40X)