[Malignant lymphoma of the prostate--a case report].

We report a case of prostatic malignant lymphoma causing bilateral hydronephrosis. A 73-year-old man was referred to our department, suffering from urinary frequency and gross hematuria. The mild elevation of serum prostatic tumor markers made us suspect prostatic carcinoma. He was admitted to our hospital and needle biopsy of the prostate was performed. Unexpectedly histological findings revealed "malignant lymphoma, diffuse large cell type". CT scan showed bilateral hydronephrosis, and renal function was decreased. As the patient suddenly vomited blood, gastric fiberscopy and biopsy was performed. Histological diagnosis of stomach was the same as for the prostate. After systemic chemotherapy of cyclophosphamide, adriamycin, vincristine, prednisone (CHOP) regimen, renal function improved and the tumor of stomach reduced, but his respiratory condition rapidly worsened, and he died about 1 month after chemotherapy. Malignant lymphoma involving the prostate is very rare. Especially in Japan only 19 cases have been reported including our case. Four of the 19 men were in their twenties and so we remind the urologists of the possibility of "malignant lymphoma of the prostate" in young patients with dysuria or frequency.