When Hepatitis B Virus-Associated Glomerulonephritis Mimics Lupus Nephritis: A Case of Adult-Onset Disease With Full-House Pattern.

Although membranous nephritis represents the classic presentation of hepatitis B virus--associated glomerulonephritis (HBV-GN) in children, adult cases can exhibit quite different features. In 1992, a 41-year-old man with recurrent nephrotic syndrome since 20 years was admitted for renal evaluation and underwent kidney biopsy. Light microscopy showed periodic acid methenamine silver staining with spike formation consistent with membranous nephropathy. However, electron microscopy demonstrated large electron-dense deposits distributed throughout subepithelial, subendothelial, and mesangial areas-an unusual pattern. Immunofluorescence showed a complete "full-house" pattern with positive staining for immunoglobulin (Ig)G (IgG2-IgG4), IgA, IgM, C3, C4, and C1q along the glomerular basement membrane. These findings initially suggested lupus nephritis, but comprehensive autoimmune testing proved negative, including antinuclear antibodies and anti--double-stranded DNA antibodies, with no characteristic clinical manifestations. Further evaluation showed positive serum HBV e antigen and DNA polymerase. Crucially, tissue immunostaining confirmed HBV e antigen deposition along the glomerular basement membrane, with high-magnification electron microscopy revealing virus-like particles, establishing the diagnosis of HBV-GN. Unlike the typical membranous pattern seen in pediatric HBV-GN, this adult case demonstrated lupus-like features with diverse glomerular lesions. To our knowledge, this represents the first English-language publication of this diagnostically challenging case, highlighting the need for heightened awareness of atypical adult HBV-GN presentations.