IgA nephropathy and atypical anti GBM disease: A rare dual pathology in a pediatric RPGN

Abstract

Introduction: Anti-GBM nephritis in the pediatric age group is exceedingly rare with concurrent additional pathologies being even rarer. Tissue diagnosis requires a combination of crescentic histomorphology, immunofluorescence showing “Paint brush stroke” pattern of linear IgG or rarely IgA and serum anti-GBM antibodies subject to the disease course and treatment. The authors describe one such case with a dual pathology involving IgA nephropathy and atypical anti-GBM disease. Case presentation: A thirteen-year-old girl presenting with features of rapidly progressive glomerulonephritis underwent a renal biopsy showing a mesangioproliferative histology with crescents and an immunofluorescence pattern indicating a dual pathology of IgA Nephropathy and Anti GBM Nephritis. Additional ancillary testing including staining for IgG subclasses and galactose deficient IgA (KM55) helped to confirm the diagnosis. She responded to steroid pulses and plasma exchange therapy, was off dialysis after 8 weeks with serum creatinine of 1.5 mg/dl however remains proteinuric at last follow up. Conclusion: Concurrent Anti-GBM nephritis and IgA nephropathy is a rare occurrence and possibly arises from a complex interaction between the anti-GBM antibodies and the basement membrane unmasking the antigens for IgA antibodies. Additional newer techniques like immunofluorescence for KM 55 are helpful in establishing the dual pathology.