Benign lesions / conditions

Authors: Komal Arora, M.D. (see Authors page)

Revised: 28 July 2016, last major update July 2012

Copyright: (c) 2003-2016,, Inc.

PubMed search: prostatic melanosis
Cite this page: Melanosis. website. Accessed October 17th, 2018.
Definition / general
Case reports
  • None - no clinical significance by itself
Microscopic (histologic) images

Images hosted on PathOut server:

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