Primary renal non‐Hodgkin's lymphoma. An unusual extranodal site

Background. Primary renal non‐Hodgkin's lymphoma (NHL) is rare. Because the renal parenchyma does not have lymphatics, the existence of this entity has been questioned. The goal of this study was to determine the clinical presentation, pathologic features, and disease course of patients with primary renal NHL and review the pertinent literature on this unusual extranodal NHL. Methods. All medical records from the Mayo Clinic from 1976 to 1992 with the diagnosis of renal NHL were retrospectively reviewed. One‐hundred seventy‐six cases were identified, five of which met the criteria for primary renal NHL. The clinical, pathologic, and radiographic features were reviewed in detail and are the basis of this report. Results. The median age at diagnosis of the five patients with primary renal NHL was 60 years (range, 52‐63 years) with a male‐to‐female ratio of 2:3. All patients had flank pain as their initial presentation. Urinalysis was abnormal in only one patient. In three patients, the serum creatinine was elevated. Tumor histology was diffuse large cell in four cases; and small noncleaved non‐Burkitt's in one. All five were B‐cell immunophenotype. All patients received combination chemotherapy. Although the median survival for the group was only eight months, two remain in complete remission longer than 80 months from therapy. These two had total removal of macroscopic lymphoma and received combination chemotherapy and consolidation radiotherapy. Conclusions. Primary renal non‐Hodgkin's lymphoma does exist. Patients whose lymphomas were completely resected macroscopically and who received combination chemotherapy with consolidation radiation therapy had long disease free survival. Patients with bilateral renal involvement or no debulking of the renal lymphoma tended to have poorer survival.