Sequential development of anti-GBM nephritis and ANCA-associated Pauci-immune glomerulonephritis

The medical history is presented of a 23-year-old man experiencing three episodes of pulmonary-renal syndrome. On the first occasion, a diagnosis of anti-glomerular basement membrane (GBM) disease (with linear deposition of immunoglobulin G [IgG] along the GBM) was made, whereas anti-neutrophil cytoplasmic autoantibodies were also present in serum. On the third occasion, 5 years later, p-ANCA-associated vasculitis (with pauci-immune crescentic glomerulonephritis) was diagnosed, whereas anti-GBM antibodies were absent. The current literature on ANCA-positive anti-GBM disease is briefly reviewed. A substantial proportion (20% to 30%) of patients with histologically and serologically proven anti-GBM nephritis display the presence of ANCA as well. In this group of patients with dual antibodies, clinical and histological findings suggest that ANCA are not merely epiphenomena, but are of pathogenetic importance and might be responsible for an initial vasculitic insult to the kidney with resultant secondary anti-GBM nephritis. The clinical course in our patient lends further support to this concept. Histological demonstration of anti-GBM nephritis followed by ANCA-associated pauci-immune glomerulonephritis in a single patient has not been reported before.