Imatinib therapy for non-infection-related type II cryoglobulinemia with membranoproliferative glomerulonephritis.

Cryoglobulinemia is a systemic immune complex-mediated vasculitis that can have significant morbidity and mortality. The current treatment for cryoglobulinemia, including chlorambucil, steroids, plasmapheresis, and rituximab, is lacking in terms of efficacy, safety, and relapse rates. Imatinib, a tyrosine kinase inhibitor, has been shown to ameliorate the phenotype and kidney injury in a thymic stromal lymphopoietin transgenic mouse model of cryoglobulinemia. We present a case of type II cryoglobulinemia with severe kidney involvement treated with 400 mg of imatinib administered orally daily, plasmapheresis, and steroids, initially with resolution of symptoms, normalization of creatinine level, and marked improvement in proteinuria and cryocrit. Furthermore, on withdrawal of imatinib therapy, proteinuria, creatinine level, and cryocrit worsened until reinstitution of therapy. After treatment resumption, creatinine level, cryocrit, proteinuria, and symptoms dramatically improved and have remained stable for more than 22 months.