Acute renal failure secondary to severe type I cryoglobulinemia following rituximab therapy for Waldenström's macroglobulinemia.

Waldenström's macroglobulinemia is rare lymphoproliferative disorder characterized by the presence of a monoclonal IgM paraproteinemia. Cryoglobulinemia is a common sequela of Waldenström's macroglobulinemia present in 8-18% of the patients. Cryoglobulinemia has also been described as occurring after treatment with rituximab. In the previous report, the cryoglobulinemia was a transient phenomenon and did not carry any adverse effect. We present a case of an 80-year-old male with Waldenström's macroglobulinemia in whom the rituximab-induced cryoglobulinemia resulted in acute renal failure and a vasculitic rash. Cryoglobulins level reached a peak of 63%. The patient was successfully treated with plasmapheresis, chlorambucil and prednisone, with near-complete recovery of renal function. As this case illustrates, the rituximab-induced cryoglobulin is not always benign. Pre- and post-treatment monitoring of the cryoglobulin level is advised in these patients.