Anti-glomerular basement membrane disease: A case report of an uncommon presentation

Anti-glomerular basement membrane (anti-GBM) disease is an uncommon autoimmune disease that classically presents as an aggressive necrotizing and crescentic glomerulonephritis (CG), with or without pulmonary hemorrhage, and typically does not relapse. The pathologic hallmark is linear staining of GBM for Immunoglobulin G (IgG) which binds to the alpha-3 chain of type IV collagen. Recent reports have noted the occurrence of anti-GBM disease with atypical clinical presentations. We describe a case of a 22-year-old female presenting an anti-GBM disease with typical histological features with a singular clinical presentation with lower limb edema, elevated serum creatinine and nephrotic range proteinuria. Renal biopsy showed signs of chronicity and direct immunofluorescence microscopy demonstrated diffuse, intense linear positivity for IgG. All serologic tests were negative, including anti-GBM antibodies. Hence, a diagnosis of atypical anti-GBM disease was made. The patient was treated initially with mycophenolate mofetil and corticosteroids. After 3 months she began to aggravate renal function so mycophenolate of mofetil was discontinued and a low dose cyclophosphamide was initiated