Heterotopic gastric mucosa in the anus and rectum: first case report of endoscopic submucosal dissection and systematic review

BACKGROUND Heterotopic gastric mucosa (HGM) is the most reported epithelial heterotopia, but it is very rare in the rectum and anus. METHODS The first case of an asymptomatic adult male with a large nonpolypoid HGM in the low rectum underwent complete resection by endoscopic submucosal dissection (ESD) is reported. The systematic review was based on a comprehensive search of MEDLINE, EMBASE and Google Scholar. Studies on humans were identified with the term 'heterotopic gastric mucosa in the rectum and /or anus.' RESULTS The search identified 79 citations, and 72 cases were evaluated comprising the present report. Congenital malformations were observed in 17 (24%) patients; rectal duplication accounted for most of the cases. The HGM was located in the anus and perineal rectum in 25 cases (41%) and low, middle and proximal pelvic rectum in 20 (33%), five (8%) and 11 cases (18%), respectively. Morphology was nonpolypoid in 37 cases (51%), polypoid in 26 cases (36%) and ulcerated in nine cases (13%). Specific anorectal symptoms were reported by 50 (69%) patients of the whole study population, and by 33 (97%) of 34 patients ≤ 18 years. Complications were observed in 23 cases (32%). The HGM was excised in 50 cases (83%). Endoscopic resection was performed in 17 cases (34%); resection was piecemeal in five of 12 lesions ≥15 mm, required argon plasma coagulation in two cases and was associated with residual tissue in two (17%). Intestinal metaplasia and an adenoma with low-grade dysplasia were described in three adults (4%). DISCUSSION This systematic review shows that the HGM in the rectum and anus may be associated with specific rectal symptoms and serious complications, mainly in the pediatric population, and a risk of malignancy in adults. Its complete excision should be recommended, and the ESD can overcome the technical limits of conventional endoscopic snare resection and avoid unnecessary surgery.