Prostate
Benign lesions / conditions
Blue nevus

Authors: Andres Matoso, M.D. (see Authors page)

Revised: 27 January 2017, last major update January 2017

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed search: prostatic blue nevus
Cite this page: Blue nevus. PathologyOutlines.com website. http://pathologyoutlines.com/topic/prostatebluenevus.html. Accessed September 25th, 2017.
Definition / general
  • Blue nevus is the term used to describe stromal melanin deposition
  • Melanosis is used to describe melanin deposition in the epithelium
  • In blue nevus, the melanin is found in S100+ prostatic stroma, probably representing stromal melanocytes (Am J Clin Pathol 1988;90:530)
  • Glands may contain some pigment due to transfer from stromal melanocytes
  • Essential features
    • Blue nevus is characterized by spindle cells within the fibromuscular stroma which contain deeply pigmented melanin
    • Normal and tumoral glands can be pigmented as a result of transfer of pigment from the melanocytes
    Terminology
    • Blue nevus is the term used to describe stromal melanin deposition
    • Melanosis is used to describe melanin deposition in the epithelium or in the epithelium and stroma
    ICD-10 coding
    • N42.9
    Epidemiology
    • Can be seen in approximately 4% of cases
    • Cases with large grossly visible lesions are very rare, with ~30 cases reported in the literature
    • Average age at presentation 66
    • Apparently no race predilection
    Sites
    • Prostatic stroma
    Clinical features
    • No clinical significance
    Diagnosis
    • Morphology and special stains
    Prognostic factors
    • Benign, has not been associated with malignant melanoma
    Case reports
    Treatment
    • Not required
    Gross description
    • Single or multiple small pigmented foci from 1 - 20 mm
    Microscopic (histologic) description
    • Fibromuscular stroma contains deeply pigmented, melanin containing spindle cells, distributed as streaming of single cells
    • Normal and tumoral glands can be pigmented as a result of transfer of pigment from the melanocytes
    Microscopic (histologic) images
    Images hosted on other servers:

    Various images

    Polygonal and elongated cells

    Pigmented stromal cells

    Positive stains
    Negative stains
    Differential diagnosis
    • Other common pigments such as hemosiderin and lipofuscin
    • Melanoma: hypercellularity, nuclear atypia and mitoses should raise the possibility of melanoma
    Additional references