Gastric mucosa heterotopia in distal rectum: a case report and narrative literature review

Gastric mucosa is one of the most common epithelial heterotopia of the gastrointestinal tract (usually involving the upper GI); however, this pathological entity has been rarely reported to affect distal rectum. A case of 4-cm polypoid lesion of distal rectum associated with recto-anal bleeding underwent complete excision by open surgical submucosal resection is reported. We conducted a comprehensive search of PubMed, Medline, and Embase. All articles that described heterotopic gastric mucosa in the rectum and/or anus were included in this narrative review. Our reported case showed the presence of heterotopic gastric mucosa associated with focal vascular ectasia in the lower rectum. No signs of Helicobacter pylori were detected. The narrative review identified 47 case reports in the literature. Gastric heterotopia resulted more common in males 27 (57.45%) than females 20 (42.55%), with a median age of diagnosis of 32.5 years. Symptoms ranged from asymptomatic 8 (17.02%) to diarrhea 2 (4.25%), anal tenesmus 5 (10.63%), anal pain 7 (14.89%), abdominal pain 8 (17.02%), or GI bleeding 26 (55.32%). The lesions macroscopically appeared as polypoid neoformations 14 (29.79%), erythematous patches 13 (27.66%), rectal ulcers 6 (12.76%), rectal diverticulum 3 (6.38%), or hemorrhoid 1 (2.13%). Endoscopic mucosectomy was performed in 19 cases (40.43%); in 11 cases, no treatment was done (23.40%); and 7 patients proceeded to transanal diverticulectomy or mucosectomy (14.89%). Gastric heterotopia in the rectum is a very rare pathology that has to be considered in case of undetermined lower GI bleeding. The best diagnostic tool still remains endoscopy or open surgical exploration associated with lesion biopsy and histopathological exam. Once diagnosis is confirmed, a radical surgical excision is advised due to its life quality compromising symptoms and minimal risk of neoplastic degeneration.