Schwannoma of the colon and rectum: a systematic literature review

Schwannomas of the colon and rectum are rare among gastrointestinal schwannomas. They are usually discovered incidentally as a submucosal mass on routine colonoscopy and diagnosed on pathologic examination of the operative specimen. Little information exists on the diagnosis and management of this rare entity. The aim of this study is to report a case of cecal schwannoma and the results of a systematic review of colorectal schwannoma in the literature.

PubMed, Scopus, and Cochrane database searches were performed for case reports and case series of colonic and rectal schwannoma. Ninety-five patients with colonic or rectal schwannoma from 70 articles were included. Median age was 61.5 years (59% female). Presentation was asymptomatic (28%), rectorrhagia (23.2%), or abdominal pain (15.8%). Schwannoma occurred in the left and sigmoid colon in 36.8%, in the cecum and right colon in 30.5%, and in the rectum in 21.1%. Median tumor size was 3 cm and 56.2% of patients who underwent preoperative colonoscopy had a typical smooth submucosal mass. At pathology, 97.9, 13.7, and 5.3% of schwannomas stained positive for S100, vimentin, and GFAP, respectively. The median mitotic index was 1/50.

Colorectal schwannoma is a very rare subtype of gastrointestinal schwannoma which occurs in the elderly, almost equally in men and women. Schwannoma should be included in the differential diagnosis of a submucosal lesion along with gastrointestinal stromal tumor, neuro-endocrine tumors, and leiomyoma-leiomyosarcoma. Definitive diagnosis is based on immunohistochemistry of the operative specimen. Rarely malignant, surgery is the mainstay of treatment.