Primary malignant lymphoma of the urinary bladder is very rare. Less than 100 cases have been reported. The best treatment approach for this disease remained unknown.

            In this article we reported a 41-year-old-female who was admitted to Sina hospital with the chief complaint of macrohematuria that was followed by dysuria , frequency , noturia and urgency. Other examinations were normal and there was no organomegaly and lymphadenopathy.

            In ultrasonography the thickening of trigone zone of the urinary bladder was reported. The patient underwent a transurethral biopsy of the bladder that revealed malignant lymphoma , intermediate grade , diffuse mixed small and large cell type ( B-cell lymphoma). The reports of computed tomography scan of the thorax , abdomen and pelvis and bonemarrow biopsy were normal and results of metastatic work up were negative.

            Primary lymphoma of the urinary bladder was diagnosed and a combination of systemic chemotherapy and relatively low dose irradiation were done for the patient. The patient is in complete remission with this kind of treatment now.