Incidental Subepithelial Sigmoid Colon Lesion

Abstract

63-year-old woman presented for screening coAlonoscopy that revealed a 15-mm subepithelial lesion on a short stalk in the sigmoid colon (Figure A). Endoscopic ultrasound showed a well-defined, hypoechoic lesion limited to the muscularis mucosae (MM) (Figure B). To decrease the risk of postpolypectomy bleeding, a detachable endoloop (HX-400U-30; Olympus Corporation, Tokyo, Japan) was placed at the base of the lesion, which was then successfully resected without complications. Histopathology showed proliferation of smooth muscle cells in the MM with negative resection margins (Figure C). Immunohistochemistry was positive for smooth muscle actin and negative for CD-117, DOG1, and S-100. These findings were consistent with a colonic leiomyoma. Gastrointestinal leiomyomas, subepithelial benign smooth muscle tumors, are most commonly found in the esophagus. Colonic leiomyomas (Figure A) are rare, constitute only 3% of these tumors, and are usually located in the rectosigmoid area. They are most commonly asymptomatic but can present with abdominal pain, obstruction, bleeding, or perforation. Endoscopic resection is a safe option in select lesions. If the tumor is confirmed by endoscopic ultrasound to arise from the MM (Figure B), it can be safely resected during endoscopy. Alternatively, safety of resection can be confirmed by submucosal injection technique in an attempt to lift the lesion. Positive non-lifting sign is