Primary malignant lymphoma of the bladder. We treated 11 patients with primary malignant lymphoma of the bladder. The typical patient is a woman more than 50 years old who presents with urgency and frequency of micturition, and occasionally gross hematuria. Hydronephrosis is present in half of the patients and cystoscopy usually reveals a solid tumor. Partial cystectomy, when feasible, with or without radiotherapy and chemotherapy is the usual treatment modality. When localized to the bladder, malignant lymphoma has an over-all favorable prognosis. 