A Rare Case of Massive Lower Gastrointestinal Bleeding as a Late Complication of Microscopic Polyangitis

Introduction: Microscopic polyangiitis (MPA) is an p-ANCA positive systemic necrotizing vasculitis affecting small vessels (capillaries) mainly in the kidney and lung. There also can be involvement of the skin, nerves, and gastrointestinal tract; however, major gastrointestinal (GI) bleeding is rare (<5%) and often a late presentation. A 63-year-old male with past medical history significant for interstitial lung disease (ILD) requiring 3 liters oxygen (etiology suspected to be asbestos exposure) and recent renal failure due to unknown etiology requiring dialysis presented with bright red blood per rectum. On evaluation his vitals were unstable, blood pressure 85/40 mm Hg, pulse 120 bpm, respiratory rate at 30 breaths per minute, and oxygen saturation of 90% on 6 liters. Notable labs was a hemoglobin of 6 gm/dL. He was resuscitated with blood products and fluids, stabilized, and sent for CT scan showing descending colon phlegmon. Tagged RBC scan located bleed to the same area. Angiography did not demonstrate any outpouching of the vessels and appeared congested in the descending colon. It did not provide any additional information. No interventions were needed other than resuscitation. Vasculitis panel was positive for p-ANCA, myeloperoxidase activity, and renal biopsy showed rapidly progressive glomerulonephritis, and immunofluorescence demonstrated minimal deposition (pauci-immune). The diagnosis of microscopic polyangitis was made and patient was started on highdose steroids and rapidly improved. Gastrointestinal bleeding from MPA occurs in approximately 20-30%, however major bleeding causing shock is very rare (<5%). ILD is a broad term and applies to pulmonary fibrosis (demonstrated in imaging). Vasculitis should be excluded as a cause of ILD as it is treatable and is a systemic disorder. Treatment with steroids and cytotoxic agents have proven to have good results for MPA at preventing further exacerbations of pulmonary and gastrointestinal manifestations. If the diagnosis of MPA had been made at an earlier time the patient would have been on steroid/cyclophosphamide therapy and the GI bleeding may have been prevented.