A Case of Inflammatory Myofibroblastic Tumor of the Ascending Colon Diagnosed in a Patient with Fever of Unknown Origin

Abstract

A 71-year old woman was admitted to another hospital with a history of persistent fever and body weight loss. Abdominal ultrasonography showed a hypoechoic mass in the right abdomen and she was referred to our hospital. At her first visit to our hospital, she had fever (37.5°C) and an elevated serum CRP level, but no abdominal symptoms. Computed tomography revealed a hypervascular mass of the ascending colon measuring 7 cm in diameter. Colonoscopy revealed a large yellowish submucosal tumor in the ascending colon. Examination of colonoscopic biopsy specimens revealed only necrotic tissue and was not helpful for diagnosis. The patient continued to have persistent fever and show body weight loss despite administration of antibiotics. Because further examination revealed no other inflammatory focus, we performed a right hemicolectomy. The fever and inflammatory response promptly improved after the operation. The histopathological diagnosis was inflammatory myofibroblastic tumor (IMT) of the ascending colon. IMT is an uncommon neoplasm composed of proliferating myofibroblasts and infiltrating inflammatory cells. It occurs most commonly in the lung, and colorectal IMTs are rare. Herein, we report a case of IMT of the ascending colon, with a review of the literature.