A 60-year-old woman with a history of chronic cystitis is referred to a urologist because of hematuria. Cystoscopy reveals a mass in the dome of the bladder. Biopsy shows tumor cells arranged as gland-like structures. Special stains demonstrate mucin in the cytoplasm of the tumor cells. What is the appropriate diagnosis?

Adenocarcinoma of the bladder accounts for only 1% of all malignant tumors of the bladder. It originates from foci of cystitis glandularis or intestinal metaplasia or from remnants of urachal epithelium in the bladder dome. Most bladder adenocarcinomas are deeply invasive at the time of initial presentation and are not curable. The other choices do not feature mucin production. Squamous cell carcinoma of the bladder (choice C) develops in foci of squamous metaplasia, usually due to schistosomiasis.Diagnosis: Adenocarcinoma of bladder