Lupus membranous glomerulonephritis mimicking hepatitis C-associated nephropathy.

About 20% to 40% of hepatitis C virus (HCV)-infected patients have antinuclear antibody (ANA) seropositivity. Despite the high prevalence of ANA seropositivity in HCV infection, only a few cases of systemic lupus erythematosus (SLE) coinciding with HCV infection have been reported. This discrepancy may be the result of underdiagnosing SLE in patients with chronic HCV infection. The possible underdiagnosis of SLE in HCV-infected patients may be of great concern because interferon-based therapy should be avoided in patients with autoimmune diseases. We report a case of a patient with chronic HCV infection who presented with nephrotic syndrome. She had no previous history of SLE. A kidney biopsy specimen revealed characteristic lesions of lupus membranous nephritis. Further serologic studies confirmed the diagnosis of SLE in this patient. Lupus nephropathy should be ruled out in patients with chronic HCV infection who present with kidney disease and moderate-to-high titers of ANA seropositivity because (1) the association between lupus nephritis and HCV infection may not be coincidental and (2) the diagnosis of lupus nephritis has important therapeutic implications in HCV-infected patients.