Seronegative Atypical Anti-Glomerular Basement Membrane Glomerulonephritis Associated With Thrombotic Microangiopathy: Case Report and Literature Analysis

Anti-glomerular basement membrane (GBM) antibody nephritis is defined by linear immunofluorescence staining of GBM by immunoglobulin G (IgG), typically associated with GBM rupture, fibrinoid necrosis, and crescent formation. Clinically, the patients present with rapidly worsening renal function, often with hematuria. Typical renal pathologic findings include necrotizing and crescentic glomerulonephritis. In contrast, thrombotic microangiopathy (TMA) is characterized by microvascular thrombosis, which can also lead to acute kidney injury. Thrombotic microangiopathy is associated with some systemic diseases and has characteristic clinical features of microangiopathic hemolytic anemia, platelet consumption, and multiple organ failure. Anti-GBM nephritis associated with TMA has rarely been reported. We describe an unusual case of atypical anti-GBM disease without crescent formation or necrosis but with light microscopic and ultrastructural features consistent with endothelial cell injury and glomerular-limited TMA.