Basal cell hyperplasia: an unusual diagnostic dilemma on prostate needle biopsies.

Basal cell hyperplasia (BCH) is a well-recognized entity on transurethral resection specimens, but it is an uncommon finding on prostatic needle biopsies, and the diagnostic difficulties with it have not been fully defined on this material. A 13-year (1991-2003) retrospective review of the consult files of one of the authors was performed. In all cases, the focus of BCH was referred for consultation to rule out adenocarcinoma. Thirty-three cases of prominent BCH were identified. The dominant pattern of BCH consisted of either glands (26/33) or solid nests (7/33). Other minor patterns included cribriform (5), pseudocribriform (4), cords (1), and adenoid basal (1). Twelve of 33 cases showed an infiltrative pattern. Other features of BCH included prominent nucleoli (14/33), abnormal secretions (17/33 with dense pink and/or blue mucin), mitoses (6/33), altered stroma with increased cellularity (6/33), calcifications (6/33), intraluminal crystalloids (3/33) and perineural invasion (1/33). By immunohistochemistry, 7 (100%) out of 7 were positive for p63 and 14 (88%) of 16 were positive for high molecular weight cytokeratin. No cases (0/6) were positive for alpha-methylacyl-coenzyme A racemase. Basal cell hyperplasia, as a mimicker of cancer, is an uncommon entity encountered on prostatic needle biopsies. Helpful features for its diagnosis include solid nests, pseudocribriform glands, multilayering of cells, calcifications, and cellular stroma. Immunohistochemistry can be useful for documenting the basal cell layer and demonstrating negative racemase staining.