Granulomatous prostatitis: distinction among allergic, nonspecific, and post-transurethral resection lesions.

A variety of granulomatous lesions of the prostate, with and without extensive infiltration by eosinophils, have been described. Differing concepts of their pathogenesis, and especially of their relation to allergic states, have produced confusion and controversy. In a review of 62 patients in whom granulomatous lesions in the prostate were diagnosed from 1950 to 1982 at The Johns Hopkins Hospital, the authors identified four major categories. In nine cases specific granulomatous prostatitis was caused by tuberculosis and had typical caseous foci. Nonspecific granulomatous prostatitis was present in 31 cases. These lesions were densely cellular, granulomatous reactions extending throughout entire lobules; three were also characterized by extensive infiltration by eosinophils. Post-transurethral resection granulomas were found in 13 patients who had recently undergone prostatic surgery. These granulomas closely resembled rheumatoid nodules, and four were surrounded by numerous eosinophils. In nine patients the causes of granulomatous prostatitis were varied: two patients had malacoplakia, one had sarcoid, and six had foreign body-type granulomatous. No cases of allergic granulomatous prostatitis were identified. Nonspecific and post-transurethral resection granulomatous prostatitis may both show abundant infiltration by eosinophils and appear histologically identical to the condition that has been described as allergic granulomatous prostatitis; however, in this series both occurred in the absence of asthma or other allergies. The distinction between the rare allergic granulomatous prostatitis, as a reflection of a more generalized allergic reaction, and both post-transurethral resection granulomas and nonspecific granulomatous prostatitis is important, given the differences in clinical outcome and treatment.