Crohn's Disease Presenting as Granulomatous Appendicitis

Granulomatous appendicitis is uncommon. It can be caused by infectious or systemic disorders, such as Crohn's disease (CD) and sarcoidosis. It is therefore essential to investigate systematic causes of granulomatous appendicitis after surgery by appropriate examinations. It is also rare for acute appendiceal inflammation to develop due to active CD. We herein report a case of CD presenting as granulomatous appendicitis. The patient was a 28-year-old man who arrived at the emergency room with right lower abdominal pain. Computed tomography showed a low-density lesion with a clear boundary and a small high-density spot in its center behind the cecum. Acute appendicitis with abscess formation was suspected and conservative treatment was started. After 3 consecutive days of conservative treatment there was no improvement in his condition. We therefore performed open appendectomy. Histopathological examination showed numerous noncaseous epithelioid granulomas in the wall of the appendix. Specific staining revealed no evidence of acid-fast bacilli or fungi. During follow-up after discharge, colonoscopy demonstrated erosion from the cecum to the transverse colon. A colon biopsy showed severe inflammation with cryptitis, Paneth cells, and a granulomatous lesion. The patient was therefore diagnosed with CD and treatment with mesalazine was started. Careful examination is necessary to diagnose and properly treat patients with granulomatous inflammation of the appendix.