Malignant lymphoma presenting as a renal mass: four cases.

Primary lymphoma of the kidney is extremely rare; most lymphomatous renal masses represent extension from adjacent sites of disease or involvement by generalized disease (4,9,12). Three men and one woman, 45 to 71 years of age, presented with solitary renal masses clinically thought to be renal cell carcinoma. Each experienced abdominal pain, one with hematuria and one with "B" symptoms. Physical examination revealed no peripheral lymphadenopathy or hepatosplenomegaly. Lactic dehydrogenase (LDH) was elevated in three cases, and blood urea nitrogen (BUN) and creatinine were slightly increased in two. Two cases were diagnosed correctly from needle biopsy, with ultrastructural confirmation in one case and marker studies, DNA flow cytometry, and cytogenetics in the other. Because of a presumptive diagnosis of renal cell carcinoma, two patients underwent nephrectomy. Three cases were large-cell lymphoma, and one, small noncleaved cell lymphoma.