Benign lesions / conditions

Topic Completed: 1 July 2012

Revised: 12 September 2019

Copyright: 2003-2019,, Inc.

PubMed search: prostatic melanosis

Komal Arora, M.D.
Page views in 2018: 286
Page views in 2019 to date: 202
Cite this page: Arora K. Melanosis. website. Accessed September 17th, 2019.
Definition / general
Case reports
  • None - no clinical significance by itself
Microscopic (histologic) images

Case of the Week #137

Various images

Positive stains
  • S100 (melanocytes)
Electron microscopy description
  • Melanosomes
Differential diagnosis
  • Lipofuscin: chracteristic of ejaculatory ducts and seminal vesicles but also found in prostatic epithelium, golden yellow-brown to gray-brown granules, positive for Fontana-Masson, PAS with diastase, Congo red, Luxol fast blue, Oil-red-O and Ziehl-Neelsen stains; bleached by permanganate, negative for Prussian blue (Am J Surg Pathol 1994;18:446, Mod Pathol 1996;9:791)
  • Blue nevus: spindled stromal cells with marked melanin deposition, nevus cells without pigment are usually present
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