When a polyp is not a polyp: incidental finding of a sigmoid schwannoma at first colonoscopic screening

Abstract

Schwannomas, peripheral nerve sheath tumours arising from Schwann cells, are often associated with inherited disorders such as neurofibromatosis. Gastrointestinal schwannomas, while rare, have been reported in those without personal or family history of neurofibromatosis. Diagnoses of these lesions, however, typically follow evaluations prompted by symptomatic presentations associated with abdominal pain, rectal bleeding, change in bowel habits or positive results on faecal occult blood tests performed for colorectal cancer screening. Further, management of these predominantly benign lesions commonly incorporates surgical resection. We present the case of a sigmoid schwannoma found in an asymptomatic individual on first screening colonoscopy and treated with complete endoscopic polypectomy with anticipated surveillance colonoscopy.

Schwannomas of Gastrointestinal Tract; a comprehensive review

“…Since Verocay first described Schwannomas in 1910, [4,22] and Daimaru first reported GIS in 1988, [4] they are increasingly being diagnosed with the recent advances in diagnostic technology and immunohistochemistry [4,22]. They do occur sporadically but not that commonly with NFs [20,22,23]. These tumors can arise in any part of the GI tract from esophagus to colon and rectum, [4,11,17] and rarely in the small intestine [17,24,25].…”

“…70% GIS occur in the stomach [20]. These slow growing soft tissue, spindle cell tumors constitute 1% of GI tumors, [4,22] 0.2% of all gastric tumors, [13,17] and 2-8% of GI mesenchymal tumors [4,13,[22][23][24][25]. In comparison, the most common, the other GI spindle cell mesenchymal tumor GIST, occurs 50-100 times more commonly than GIS [11] and constitutes 80% GI mesenchymal tumors [13] Albeit both these spindle cell mesenchymal tumors may have similar clinical presentation and features of resemblance on endoscopy or colonoscopy, they need to be differentiated early from each other pre, peri or postoperatively as they run altogether different course in connection with complications, treatment and prognosis with GIST tumors being more malignant than GIS.…”

“…Schwannomas in esophagus [13,24,32] can present with dysphagia [7,9] and those originating from small intestine can present with fatigue, anemia, [8] intussusception, and mass abdomen [9,13,33]. Sometimes these tumors are picked up coincidentally [32] during routine endoscopic screening [34] or by endoscopic evaluations prompted by changes in bowel habits, abdominal pain, [13] GI bleeding, [4,13,14] difficulty in defecation [1,9] or positive occult blood tests performed during colorectal screening [23,35]. When they occur in stomach, the commonest site of these tumors, they are usually asymptomatic [36,37] and in the subset of symptomatic patients, presentation due to bleeding as the first symptom is seen in 14% cases; and this usually in the form of melena and rarely as hematemesis [36].…”

Transanal Minimally Invasive Surgery for Local Excision of a Rectal Schwannoma

“…chwannoma is a rare nerve sheath tumor, which frequently appears in extragastrointestinal locations. [1][2][3] It is extremely rare in the rectum. [4][5][6] In this video (see video at http://links.lww.com/DCR/B713), we present a case of a rectal Schwannoma, resected via transanal minimally invasive surgery (TAMIS).…”