[Primary malignant lymphoma of the bladder: a case report].

An 86-year-old woman was admitted to our hospital with genitourinary bleeding. Abdominal computerized tomography demonstrated a low density mass on the posterior wall of the bladder. Cystoscopy revealed a nonpapillary bladder tumor. A transurethral cold cup biopsy showed lymphocytic infiltration with no malignant cells. She died 2 years after the initial presentation and autopsy revealed malignant lymphoma, diffuse B cell type, small cell type. A cold cup biopsy of the bladder mucosa sometimes fails to detect primary malignant lymphoma of the bladder because of its submucosal location.