Sequential development of pulmonary renal syndrome associated with c-ANCA 3 years after development of anti-GBM glomerulonephritis.

There is evidence that there is an association between anti-glomerular basement membrane (anti-GBM) antibodies and anti-neutrophil cytoplasmic antibodies (ANCA) in the development of pulmonary renal syndrome (PRS) [1–7]. Whether these two distinct circulating auto-antibodies have some pathological interaction remains unclear. Studies have shown that 30% of patients with anti-GBM disease will test positive for ANCA [1,8]. There is evidence in these studies that the presence of both anti-GBM and ANCA auto-antibodies may lead to a better clinical course than in patients with anti-GBM disease alone regardless of cor p-ANCA specificity. This suggests that dual positivity is not just an epiphenomenon, but may be pathologically linked. Cases of vasculitis developing after anti-GBM disease have been reported, but it is uncertain whether these cases are incidental. We present here a case of anti-GBM glomerulonephritis where a patient had dual positivity of anti-GBM and c-ANCA/PR3 and then 3 years later developed c-ANCA/PR3 associated pauci-immune vasculitis. There are other cases in the literature where patients who have initially been diagnosed with anti-GBM disease subsequently develop p-ANCA/MPO PRS [2–4,7,9]. Most of these cases did not have dual positivity on initial presentation. Our case, included with others, supports a potential link in the underlying disease process leading to both anti-GBM disease and ANCA associated vasculitis that is not related to ANCA specificity.