Immunoglobulin M 'Flare' after rituximab-associated acute tubular necrosis in Waldenström's macroglobulinemia.

Waldenström's macroglobulinemia (WM) is a low-grade lymphoplasmacytic lymphoma characterized by a circulating monoclonal IgM. Renal involvement in classical cases of WM is rare, and the pathological hallmark finding in the renal biopsy specimen is a thrombotic microangiopathy. We report the case of a 69-year-old man with the diagnosis of WM for 3 months before he presented with acute renal failure (ARF). A renal biopsy performed suggested the diagnosis of acute tubular necrosis. The diagnosis of ARF related to IgM flare after Rituximab therapy was made.