LAUSR

Diffuse crescentic involvement in fibrillary glomerulonephritis (FGN) is very rare. We describe a case of FGN with diffuse crescents in a patient who presented with clinical findings concerning for rapidly progressive kidney failure and pathologic findings suggestive of anti-glomerular basement membrane (GBM) disease. Serologies for anti-neutrophil cytoplasmic antibody (ANCA) and anti-GBM were negative. IgG subtyping showed IgG1 dominance, which has not been described in FGN. We present this unique case to emphasize the importance of considering FGN in biopsies showing diffuse crescentic glomerulonephritis with linear IgG staining of glomerular capillary walls, especially in the absence of other significant proliferative changes.