Clinicopathological Characteristics of Anti-Glomerular Basement Membrane Disease with Atypical Features

Objective: Anti-glomerular basement membrane (anti-GBM) disease is a rare disorder characterized by pulmonary and kidney involvement, which is a lesser-known variant of this disease with an unpredictable clinical course. The aim of this study is to present 4 cases of anti-GBM disease with atypical clinicopathological findings. Methods: This study included patients diagnosed with atypical anti-GBM disease at Gazi University Hospital between January 2012 and December 2020. Results: Four patients with atypical anti-GBM disease were included in this study. All the patients were male, and only 1 of them was seropositive for anti-GBM antibody, albeit at a low serum titer. Three of them had lung involvement, and all of them had hematuria with proteinuria (2 were in the nephrotic range). Kidney biopsy findings of the patients were heterogeneous and included endocapillary proliferation with crescents, nodular glomerulosclerosis with crescents, necrotizing diffuse crescentic glomerulonephritis, and mesangial and endocapillary proliferative glomerulonephritis without crescents. Only 1 case did not show glomerular necrotizing lesions. The presence of linear staining with IgG along the glomerular capillary walls was the common immunofluorescence finding for all. The clinical course of all 4 cases was different from each other, while 2 patients required permanent kidney replacement therapy, 1 patient died due to pulmonary complications, and 1 patient died because of immunosuppression-related complications. Conclusion: Atypical anti-GBM disease is rare and may manifest itself with both intriguing clinical and pathological findings. The first step for an accurate diagnosis is to be aware of the disease.