Prostatic melanosis with involvement of benign and malignant epithelium.

We report an unusual case of prostatic melanosis. Grossly, the majority of prostatic chips contained areas of black discoloration. Microscopically, pigment was identified within the prostatic stroma, in benign prostatic ducts and within the cells of a well differentiated prostatic adenocarcinoma. The pigment was identified as melanin by histochemical methods and electron microscopy. The histogenesis of prostatic melanosis is discussed and it is proposed that the melanin pigment is derived from (aberrant) stromal melanocytes.