Granulomatosis With Polyangiitis: A Pauci-Immune Rapidly Progressive Glomerulonephritis With Isolated Renal Involvement in an Elderly Male.

Granulomatosis with polyangiitis (GPA) is a necrotizing vasculitis with upper and lower respiratory tract and renal system involvement. We present a case of a 59-year-old male presenting with complaints of abdominal pain with deranged renal function and acute increase in creatinine level. On investigation, the antineutrophil cytoplasmic autoantibody, cytoplasmic (c-ANCA) was found to be significantly elevated in association with pauci-immune crescentic glomerulonephritis on biopsy. This was diagnostic of Wegener's granulomatosis. He was treated with intravenous cyclophosphamide 10 mg/kg/pulse along with steroids at 1 mg/kg/day for induction and trimethoprim/sulfamethoxazole (TMP-SMX) 80/400 mg for pneumocystis carinii pneumonia (PCP) prophylaxis after a negative tuberculosis QuantiFERON® assay (Qiagen, Netherlands). On discharge, he was on TMP-SMX prophylaxis for PCP, prednisone 60 mg daily, and cyclophosphamide on pulse dosing every 14 days with instructions to follow up. The patient showed improvement in therapy.