Histopathological spectrum of 364 prostatic specimens including immunohistochemistry with special reference to grey zone lesions.

Purpose: Prostatic lesions on routine staining sometimes cause a diagnostic dilemma, especially when malignant tissue is limited and is mixed with benign prostatic glands or because of the presence of benign mimickers of carcinoma. The application of immunohistochemistry contributes a valuable differential diagnosis. This study aimed to evaluate a complete spectrum of various prostatic lesions and to supplement the histopathological diagnosis with immunohistochemistry in suspicious or atypical cases.

Methods: A total of 364 consecutive prostatic specimens were evaluated. Routine hematoxylin and eosin staining and immunohistochemical staining against 34βE12 cytokeratin and proliferative marker (alpha-methylacyl-CoA-racemase, AMACR) were performed by use of the peroxidase antiperoxidase method.

Results: Benign prostatic hyperplasia was the most frequent finding and involved 285 patients (78.3%). Prostatitis (majority nonspecific) formed the predominant subgroup in nonneoplastic lesions (n=119, 32.7%). The incidence of carcinoma was low (n=73, 20.1%). Of the 26 atypical or suspicious cases, 18 cases were positive for high molecular weight cytokeratin (high molecular weight cytokeratin, HMWCK) only, 4 cases were positive for AMACR only, and 4 cases showed positivity for both HMWCK and AMACR.

Conclusions: Biopsy remains the gold standard. However, as an adjunct to biopsy, proliferative markers and basal cell markers have value for resolving suspicious or atypical cases.