Cryptococcal Prostatitis Forming Caseous and Suppurative Granulomas Diagnosed by Needle Biopsy: A Case Report

Cryptococcal granulomatous prostatitis is extremely rare, and there have been few reports of its diagnosis by prostate needle biopsy. The patient, an 81–year–old man, was receiving immunosuppressive treatment for rheumatoid arthritis. He had an oropharyngeal ulcer, and it was diagnosed alongside a methotrexate-related diffuse large B-cell lymphoma. A systemic imaging examination revealed a prostatic tumor-like mass clinically suspected to be prostatic cancer, and a needle biopsy was performed. The biopsy specimen showed various types of inflammatory cell infiltration, and suppurative granuloma and caseous granuloma were observed. Both granulomas showed multiple round and oval organisms that were revealed with Grocott methenamine silver staining. Acid–fast bacilli were not detected by Ziehl–Neelsen staining. We histologically diagnosed granulomatous prostatitis caused by Cryptococcus infection. Caseous granulomas often develop in the prostate after bacillus Calmette–Guerin immunotherapy for bladder cancer, although the possibility of cryptococcal granulomatous prostatitis should also be considered.