Sigmoid colon Schwannoma simulating colon cancer.

Schwannomas tumours are uncommonly developed in the gastrointestinal tract (2-6%), located in 12% of cases in small and large intestines. An 87-year-old woman was studied due to epigastric pain and dyspepsia. CT scan and colonoscopy showed a neoplastic process in the sigmoid colon. It was performed an oncologic laparoscopic sigmoidectomy. Histological study described a schwannoma and a positive immunohistochemistry to S-100. The diagnostic challenge is that this is a submucosa lesion, therefore, endoscopy biopsy is realized only in the mucosa. This becomes the differential diagnostic very difficult in order to differentiate from another mesenchymal tumor (GIST or leiomyoma). The immunohistochemistry helps in the diagnostic if it is positive to S- 100 and negative to C-KIT, CD-34, actine and desmine (findings of GIST tumors and leiomyoma). In conclusion, schwannoma diagnostic is tough. Those are asymptomatic tumors with nonspecific radiological findings. Diagnostic confirmation is a S-100 positive immunohistochemistry in the histological study.