Bacillus Calmette-Guerin granuloma in seminal vesicle: Report of the first case in the English literature

A 64-year-old man underwent a radical cystoprostatectomy for intravesical bacillus Calmette-Guerin (BCG) therapy-resistant, recurrent muscle invasive transitional cell carcinoma (TCC) of the urinary bladder. He had a history of left radical nephroureterectomy for a papillary TCC of the left ureter 10 months ago. On microscopic examination, not only multifocal residual papillary TCCs in the urinary bladder but also multiple small granulomas in the urinary bladder and prostate were noted. Interestingly, unusually severe granulomatous inflammation accompanying focal central caseating necrosis was identified in the subepithelial tissue of the left seminal vesicle and vas deferens. Neither prostatic adenocarcinoma nor TCC involvement was identified in the prostate and seminal vesicles. A few acid-fast bacilli were identified by the Ziehl-Neelsen staining in the seminal vesicle granulomas, confirming the BCG-induced inflammation. To the best of our knowledge, this is the first case of BCG-induced granuloma involving the seminal vesicle. It is uncertain why only the left seminal vesicle was involved with BCG granulomas and the incidence and mechanism of seminal vesicle BCG granuloma await more cases.