Skin-nontumor / Clinical Dermatology
Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Memorial University of Newfoundland (see Reviewers page)
Revised: 24 August 2011, last major update August 2010
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.
● Neural crest origin
● In basal epidermis, hair follicles, most squamous mucous membranes, leptomeninges
● The ratio of melanocytes to basal cells ranges from approximately 1:4 on the cheek to 1:10 on the limbs
● Contain dendrites, delicate cytoplasmic processes that extend between keratinocytes
● Upwards or lateral migration within epidermis or into papillary dermis does not necessarily indicate malignancy
● Cytoplasm is clear due to retraction, nuclei typically are smaller and slightly more hyperchromatic than nuclei of adjacent keratinocytes, have uniform chromatin, indented nuclear contour, no nucleoli
● Produce melanin from tyrosine, transfer it (via cytocrinia) to adjacent epithelial cells to protect against ultraviolet rays
● Racial skin color is due to amount of melanin in keratinocytes, not number of melanocytes
Skin and melanocytes
● Fontana-Masson, tyrosinase, S100, NSE, MelanA/Mart1, microphthalmia transcription factor, vimentin, bcl2, HMB45 (activated melanocytes)
● Variable keratin in activated melanocytes
● GFAP, neurofilament; HMB45 and keratin in resting melanocytes
● Melanosomes: melanin-synthesizing organelle derived from Golgi
● Melanoblasts: immature counterpart
● Melanophages: macrophages with ingested melanin
American Academy of Dermatology
End of Skin-nontumor / Clinical Dermatology > General > Melanocytes
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