[Blue nevus of the prostate. Differential diagnosis of prostatic pigmented lesions]

Abstract

Objective: To describe a case of blue nevus of the prostate and propose a more precise terminology in order to avoid the confusion arising from the presence of melanin pigment in the prostatic epithelium and/or stroma.

Methods/results: A 58-year-old patient with adult polycystic kidney is described. The patient demonstrated clinical and radiological findings compatible with benign prostatic hyperplasia and had a PSA of 11.4 ng/ml. After three transrectal biopsies showing no malignancy, the patient underwent transurethral resection. Pathological examination of the specimen disclosed glandular-stromal hyperplasia and extensive melanin pigmentation of stroma or blue nevus of the prostate.

Conclusion: The presence of pigment in the prostate is an extraordinary histological finding that can be ascribed, in most of the cases, to one of the following conditions: a) melanosis or true melanocytosis, in which the melanin pigmentation is produced by the prostatic stromal cells, with or without involvement of the surrounding epithelium (probably in a secondary passive process); b) pseudomelanosis, in which the lipofuscin pigmentation is produced and stored by epithelial cells. In both cases the histopathological findings have no clinical significance or prognostic implications.