[III. Paraproteinemia: 3. Cryoglobulinemia]

A case of rapid amelioration of hepatitis C virus-associated cryoglobulinemic membranoproliferative glomerulonephritis treated by interferon-free directly acting antivirals for HCV in the absence of immunosuppressant

Mixed cryoglobulinemic syndrome, which is a systemic vasculitis characterized by the immune complex deposition in small- and medium-sized arteries and most often due to chronic hepatitis C virus (HCV) infection, sometimes clinically manifests as refractory glomerulonephritis or nephritic syndrome. Patients with mixed cryoglobulinemic nephropathy who have a rapidly progressive glomerulonephritis should receive immunosuppressive therapy. After disease stabilization, patients should receive concurrent therapy for the underlying HCV infection. The standard therapy of a chronic HCV infection is IFN monotherapy or IFN combined with ribavirin; however, after the introduction of direct-acting antivirals (DAAs), the standard therapy for patients with HCV genotype 1 has dramatically changed. We report a case of HCV-associated cryoglobulinemic membranoproliferative glomerulonephritis (MPGN) successfully treated by daclatasvir and asunaprevir, which are IFN-free DAAs for HCV, in combination with angiotensin II receptor blocker without immunosuppressive therapy. The patient developed severe nephrotic syndrome with progressive kidney dysfunction. Blood examination revealed a high copy number of HCV-RNA (6.4 log IU/mL, type 1), cryoglobulinemia, paraproteinemia of IgM-κ, and hypocomplementemia. Histological analysis showed MPGN type 1. These findings were compatible with those observed in HCV-associated cryoglobulinemic MPGN. This case offers original evidence for the application of newer generation of IFN-free DAAs in the treatment of HCV-associated cryoglobulinemic nephropathy.