Mucosal spreading of urothelial tumors to the seminal vesicles is very rare. We experienced a case of mucosal involvement of the seminal vesicles by a bladder tumor in a 72-year-old man. The patient had a history of transurethral resection for invasive urothelial carcinoma of the bladder 8 years previously. Radical cystoprostatectomy was performed owing to recurrent and multiple urothelial carcinoma in situ. Microscopically, the urothelial carcinoma in situ was throughout the mucosa of the urinary bladder, both ureters, the prostate, and the left seminal vesicle. To date, the implication of mucosal involvement of the seminal vesicles by urothelial carcinoma is unclear. However, careful microscopic examination is needed to avoid an erroneous diagnosis.
Keywords: Carcinoma in situ; Seminal vesicles; Urinary bladder neoplasms.