Hepatitis C virus-related heat-insoluble cryoglobulinemia and thrombotic microangiopathy.

Heat-insoluble cryoglobulinemia is rare, and its pathogenesis and comorbidities remain poorly understood. Here, the authors report a case of hepatitis C virus (HCV)-related heat-insoluble cryoglobulinemia associated with thrombotic microangiopathy and cryoglobulin-occlusive membranoproliferative glomerulonephritis. The patient, a 57-year-old woman, presented with acute kidney injury, thrombocytopenia, anemia with schistocytes, high levels of serum HCV RNA of HCV genotype 2a, rheumatoid factor positivity and high levels of serum immunoglobulin (Ig) M and Igκ. The patient's serum was positive for cryoglobulin at 4°C, and the precipitate required heating to 47°C for dissolution. Cryoglobulin immunofixation was positive for monoclonal IgM and Igκ and polyclonal IgG. However, immunofixation of the cryoglobulin supernatant was negative. Histological examination of renal biopsy revealed a membranoproliferative type I glomerulonephritis. The patient was treated with plasmapheresis, corticosteroids and antiviral therapy of peginterferon plus ribavirin, but symptoms only partially resolved.