An Exceptional Case of Crohn-Associated IgA-Mediated Goodpasture Disease.

Anti-glomerular basement membrane (anti-GBM) disease is typically mediated by IgG autoantibodies and presents with pulmonary hemorrhage and rapidly progressive glomerulonephritis, classically referred to as Goodpasture disease. We describe a novel IgA-mediated variant in a 53-year-old man with Crohn colitis, who presented with oligo-anuric acute kidney injury and hemoptysis. Despite having negative serology for anti-GBM antibodies, kidney biopsy revealed necrotizing crescentic glomerulonephritis with linear IgA deposition along the glomerular basement membrane. We suspect that a Crohn colitis flare may have incited a novel IgA-driven anti-GBM process which, remarkably, resolved in the absence of conventional immunosuppressive therapy, sharply deviating from previously reported IgA-mediated disease requiring aggressive intervention. Such a case suggests a possible link between abnormal IgA glycosylation in inflammatory bowel disease and the development of a unique IgA-mediated anti-GBM process. Recognition of this entity may broaden the diagnostic approach to seronegative pulmonary-renal syndromes and also highlight the potential for nonimmunosuppressive management.