Schwannoma in descending colon: presentation of a neoplasm in a rare location.

We present a 67-year-old male in whom a screening colonoscopy revealed an ulcerated polypoid lesion 35 cm from the anal margin. The biopsy was unspecific. CT and virtual colonography showed a 4.5 x 3.6 x 3.7 cm polypoid mass in the left colon with regional adenopathies but no distant metastases. The patient was admitted to the emergency department for rectorrhage and abdominal pain. Ultrasonography showed a colico-colic invagination caused by the polypoid mass. The patient underwent a midline laparotomy, which revealed an invagination in the descending colon, but no infiltration or distant dissemination. A segmental colectomy was performed with a mechanical sideto-side anastomosis. The patient evolved favourably. The anatomopathological study informed of a well-circumscribed yellowish-white submucosal tumour made up of spindle cells forming palisades, an intratumoural lymphoid infiltrate with peripheral nodules, and low mitotic activity. Immunohistochemical tests were positive for S-100 and CD68 but there was no reactivity for CD117, CD34, actin and CD10 (Fig. 1). The definitive diagnosis was schwannoma of the colon. No recurrence has been observed in 3 years of follow-up.