A large superior mesenteric artery aneurysm and ileal obstruction: a rare presentation of polyarteritis nodosa in an infant

Polyarteritis nodosa (PAN) is a rare form of vasculitis that occurs in childhood and affects small- and medium-sized arteries. Large aneurysms due to PAN can induce fatal complications like rupturing or occlusion of the affected arteries. Here, we report a case of a 4-month-old girl with PAN complicated by a large superior mesenteric artery aneurysm and ileal obstruction. We controlled her blood pressure to prevent the artery from rupturing. A combination of prednisolone, intravenous cyclophosphamide, and plasma exchange reduced the inflammation. She developed mechanical ileus due to ileum stricture and underwent bowel resection. Histopathological examinations revealed reparative arteritis around the healed ulcer. Her postoperative course was uneventful without further dilatation of the aneurysm. This case highlights the importance of intensive immunosuppressive therapy and appropriate blood pressure control in pediatric patients with PAN complicated by large aneurysms. Mechanical ileus can develop and may require surgical management even after remission of vasculitis.