Acute renal failure due to bilateral lymphomatous infiltrates. Primary extranodal non-Hodgkin's lymphoma (p-EN-NHL) of the kidneys: does it really exist?

Primary extranodal non-Hodgkin's lymphoma (p-EN-NHL) of the kidneys with acute renal failure as the only manifestation is very rare. The origin of neoplastic lymphoid cells in the kidneys, organs normally free of lymphoid tissue, is an unsolved problem. A literature review over the last ten years revealed only 9 adult cases, including ours that match the usual criteria: (1) renal failure as the initial presentation, (2) bilateral enlargement of the kidneys without obstruction and other organ or nodal involvement, (3) diagnosis only made by renal biopsy, (4) absence of other causes of renal failure, and (5) rapid improvement of renal function after radiotherapy or, as in our case, systemic chemotherapy