[Lymphomatous renal involvement].

The incidence of lymphomas, especially non-Hodgkin's lymphoma (NHL), has shown a steady increase over the last decades. At the same time, the prognosis has improved. Given the longer survival of lymphoma patients, pathological manifestations related to malignancy might become more frequent. In this setting, the kidney is one of the most important solid organs affected by direct or indirect lymphomatous involvement. Kidney involvement can be related to obstruction or treatment-induced toxicity, but more intriguing are 1) direct infiltration (NHL); 2) renal malignancies in patients affected by Hodgkin's disease or NHL; 3) associated glomerular diseases. Primary infiltration is rarely seen, while secondary infiltration is described most frequently in autopsy series, even in the absence of renal failure. These alterations may mimic glomerular and/or interstitial disease. The association with kidney malignancies, mostly renal cell carcinoma but also urothelial tumors in Hodgkin''s disease, is higher in lymphoma patients than in the general population: the relative risk at 10 years is about 1.5. Glomerulonephritis is described in patients with Hodgkin's disease or NHL; in the former minimal change disease is most frequent, in the latter the glomerular pattern varies widely. Glomerulonephritis can precede, be concurrent with, or follow lymphoma manifestations. Renal biopsy is often needed in this setting.