[Renal or perirenal malignant lymphoma: report of three cases].

We report three cases of renal or perirenal malignant lymphoma. The patients were a 69-year-old woman presenting with lumbago, a 43-year-old man with fever and erythema, and a 69-year-old woman with general malaise. In each case, renal or perirenal tumor was discovered by abdominal ultrasound. Biopsy and microscopic examination revealed the diagnosis of non-Hodgkin's malignant lymphoma. The computerized tomography patterns of the cases were different from each other; "direct invasion" in the first case, "solitary nodule" in the second case, and "engulfment" in the third case. Chemotherapy and/or radiation therapy were performed. Only the third case is still alive at present. The computerized tomography pattern of renal or perirenal malignant lymphoma was classified into five groups; I) multiple nodules, II) solitary nodule, III) engulfment, IV) direct invasion, V) diffuse infiltration. This classification should be useful in making an accurate and early diagnosis.