Primary Anaplastic Lymphoma Kinase‐Positive Inflammatory Myofibroblastic Tumor of the Small Bowel Detected by Capsule Endoscopy: A Case Report

Primary inflammatory myofibroblastic tumor (IMT) of the small intestine is rare, and its endoscopic characteristics remain poorly defined. We report a case of anaplastic lymphoma kinase (ALK)-positive small bowel IMT detected by capsule endoscopy (CE). A 24-year-old woman presented with epigastric pain. Contrast-enhanced computed tomography revealed a 2-cm mass in the small intestine. Double-balloon endoscopy was attempted but failed to reach the lesion. CE demonstrated a submucosal tumor-like protrusion with mild surface erythema and conspicuous whitish villous changes. Laparoscopy-assisted partial resection of the small intestine was performed, and histopathological examination with immunohistochemistry confirmed ALK-positive IMT. The postoperative course was uneventful, and no recurrence was observed during 8 months of follow-up. This case indicates that CE can provide clinically useful information for the evaluation of small bowel submucosal lesions beyond the reach of conventional endoscopy. IMT should be considered in the differential diagnosis of erythematous small bowel tumors in young patients.