Diagnostic dilemmas in the interpretation of fine-needle aspirates of granulomatous prostatitis.

We have reassessed the fine-needle aspirates of ten cases previously diagnosed as granulomatous prostatitis (GP). Presence of unequivocal epithelioid granulomas (EG) or typical caseous necrosis was required for a smear to be diagnosed as nonspecific granulomatous prostatitis (NGP) or tuberculous prostatitis (TP), respectively. As a consequence only six cases met the criteria set up for the diagnosis of NGP and two for TP. The purpose of this revision was fourfold: to find out if there are other prostatic conditions which may be confused with GP cytologically, to investigate if there is a single cytologic finding that permits a confident diagnosis of GP, to find out if the etiology can be suggested on cytologic grounds alone, and, finally, to assess if carcinoma can be ruled out safely. We conclude the following: 1) There are various prostatic conditions which share some cytologic findings with GP; 2) the presence of distinct EG is the hallmark criterion of GP; 3) NGP and TP can be safely diagnosed cytologically but other forms of GP would require additional clinical data and ancillary techniques; and 4) carcinoma can be safely distinguished from GP cytologically. To succeed in this task the cytopathologist must diagnose carcinoma only if clear-cut carcinoma cells are present and must be aware of the reactive changes induced by the inflammatory infiltrate both in duct/acinar and metaplastic cells.