Microscopic Polyangiitis Presenting with Acute Abdominal Pain Due to Rare Small Intestine Involvement

Abstract

A 44-year-old male patient was admitted to the emergency department with symptoms of acute abdominal pain, diarrhea, weight loss, and a rash on his legs. Abdominal computed tomography revealed wall thickening and diffuse ascites in the ileum. Colonoscopy showed focal nodular lesions and erosions in the terminal ileum. The diagnosis of microscopic polyangiitis (MPA) was established based on vasculitis symptoms, the presence of cytoplasmic antineutrophil cytoplasmic antibodies (cANCA) in the blood, and a skin biopsy confirming leukocytoclastic vasculitis. High-dose prednisolone (1 mg/kg) was initiated to address the kidney, skin, neurological, and severe gastrointestinal system involvement. The patient made a full recovery within two weeks of treatment initiation. Herein, we report a case of MPA with an initial presentation of diffuse small intestinal involvement manifested by acute abdominal pain. To the best of our knowledge, this specific presentation has not been previously documented in medical literature.