Gastric Heterotopia in the Rectum: Donʼt Let Looks Deceive You

Abstract

Gastric heterotopia in the rectum is an extremely rare gastrointestinal entity with very few cases reported in the literature. Although it is an uncommon finding, it can lead to serious complications including rectal bleeding, rectal and abdominal pain, and most importantly, an increased risk for malignant transformation. Here we present a very rare case of an asymptomatic patient diagnosed with gastric heterotopia of the rectum after an initial screening colonoscopy. This is the case of a 51 year-old male with a medical history of gastroesophageal reflux disease that was seen at gastroenterology clinics for initial screening colonoscopy. At evaluation the patient was asymptomatic, denying weight loss, abdominal pain, diarrhea, constipation, melena, hematochezia, rectal pain, or changes in stool caliber. The patient had no pertinent family history and the only medication taken was omeprazole twice daily. On examination, vital signs were within normal limits and his physical did not reveal any abnormal findings. Laboratory tests were unremarkable. Colonoscopy was performed without complications and revealed four diminutive sessile polyps measuring < 0.5 cm at 2cm from anal verge (Figure 1). The histopathological evaluation revealed that all four were hyperplastic polyps (Figure 2). However, one small focus of pyloric glands and overlying foveolar type epithelium was identified (Figure 2-3), consistent with heterotopic gastric mucosa of the rectum. Gastric heterotopia refers to the presence of normal gastric mucosal tissue located in a non-physiological site, entirely apart from the stomach. It can occur anywhere along the gastrointestinal tract with most common sites being the esophagus and duodenum. However, the presence of gastric mucosa in the rectum is exceedingly rare with only approximately 50 cases described in the literature. Symptoms include painless rectal bleeding, rectal and abdominal pain. Rectum involvement of gastric heterotopia is usually observed endoscopically as a polyp, diverticula or ulcer. Histopathology is essential for diagnosis, with oxyntic type mucosa typically observed. Other histologic findings include mixed oxyntic, antral mucosa and pyloric type mucosa from which adenocarcinoma can arise. These lesions have an increased risk of malignancy, which warrants great awareness by physicians and close follow up. Here we observe that these lesions can present like a typical polyp, making biopsies an essential part of any colonoscopy.1494_A Figure 1. Diminutive sessile polyp at rectum.1494_B Figure 2. (A) Focus of pyloric glands with overlying foveolar type epithelium. (B) Hyperplastic polyp with superficial serrated architecture.1494_C Figure 3. Pyloric type gastric mucosa in rectum