2019-2 / FEBRUARY 25

A 79 year old male underwent a TURP due to obstruction. The tumor was stained at the outside institution and was diffusely positive for high molecular weight cytokeratin and negative for PSA, PSAP, GATA3, synaptophysin, with a ki67 of 90%.


What is the correct diagnosis?

a) Basal cell carcinoma of the prostate
b) Small cell carcinoma
c) Adenocarcinoma of the prostate, Gleason score 5+5=10 (Grade Group 5)
d) Urothelial carcinoma

Q1. A

Basal cell carcinoma of the prostate

The tumor consists of solid basaloid nests with some peripheral palisading and focal central necrosis. Although the tumor is cellular, the cells are more uniform, and lack nuclear molding and the very high mitotic rate typically seen in small cell carcinoma. Although some small cell carcinomas do not express synaptophysin, this finding along with the morphology rules out small cell carcinoma. While some very poorly differentiated adenocarcinomas of the prostate can be negative or only show rare cells positive for prostate markers, this result along with diffuse HMWCK rules out prostate adenocarcinoma. Basal cell carcinoma of the prostate can have a wide range of morphology. The most common is adenoid cystic-like pattern and variably sized small-medium solid nests with peripheral palisading. Other patterns include basal cell hyperplasia-like which is distinguished from basal cell hyperplasia by an infiltrative growth pattern and if present admixture with other more recognizably malignant pattern. A characteristic finding that is not seen in basal cell hyperplasia is a biphasic pattern with small tubules lined by eosinophilic cells within basaloid nests. Least commonly, there are large solid nests, often with central necrosis. Most basal cell carcinomas of the prostate have an indolent course with local infiltrative behavior. A small subset behaves aggressively with local recurrences and distant metastases. The most common morphology among those with an aggressive behavior is large solid nests more often with central necrosis and high Ki67%, as seen in the current case. Basal cell carcinomas often overexpress BCL2 which was seen in the current case and not seen in basal cell hyperplasia.

Basal cell carcinoma of the prostate: a clinicopathologic study of 29 cases.
Ali TZ, Epstein JI. Am J Surg Pathol. 2007 May;31(5):697-705.

Distinction of basaloid carcinoma of the prostate from benign basal cell lesions by using immunohistochemistry for bcl-2 and Ki-67.
Yang XJ, McEntee M, Epstein JI. Hum Pathol. 1998 Dec;29(12):1447-50.

Jonathan I. Epstein
Johns Hopkins Hospital
Baltimore, MD


Basal cell carcinoma; Basal cell hyperplasia, variant