[A case report of inflammatory pseudotumor of the urinary bladder due to diverticulitis of the sigmoid colon].

A 65-year-old female presented to our hospital with a 6-month history of pollakuria, low-grade fever and urgent incontinence. Cystoscopy revealed a nonpapillary bladder tumor that was 50 mm in diameter in the trigon. Computed tomography showed the abscess between the urinary bladder and sigmoid colon. Transurethral resection was performed and the histology consisted of inflammatory lesions with inflammatory cell infiltration, which was diagnosed as an inflammatory pseudotumor due to diverticulitis of the sigmoid colon. Sigmoidectomy was subsequently performed. A fistula between the urinary bladder and the sigmoid colon was not detected. Cystoscopy 2 months after the operation revealed no signs of a bladder tumor.