Perineurioma in the sigmoid colon diagnosed and treated by endoscopic resection.

Perineuriomas are rare benign peripheral nerve sheath tumors in the gastrointestinal tract. We recently encountered a submucosal lesion in the sigmoid colon that was resected by endoscopic mucosal resection and was then diagnosed as perineurioma by immunohistochemistry. A 51-year-old female with a positive test for fecal occult blood was referred to our hospital for screening colonoscopy. Colonoscopy identified a submucosal lesion, approximately 15 mm in diameter, in the sigmoid colon. Endoscopic ultrasound showed a 15-mm tumor with a strong acoustic shadow. Endoscopic mucosal resection was performed in order to make a precise diagnosis as well as removal. The specimen revealed spindle cell proliferation without atypia, and immunostaining revealed that the spindle cells were positive for collagen type IV and glut-1, and the lesion was diagnosed as a colonic perineurioma with no malignancy. Gastroenterologists as well as pathologists should be aware of this type of submucosal lesion, and immunohistochemical evaluation is highly recommended when an unusual mesenchymal tumor is found.