Asymptomatic Gastric Heterotopia in the Rectum? A Rare Finding with Unclear Malignant Risk

Abstract

Introduction Gastric heterotopia (GHT) is the presence of normal gastric mucosa in extra-gastric regions in the gastrointestinal tract (GIT). The most common locations are the esophagus, duodenum, and Meckel's diverticulum, but rarely it may occur in the rectum resulting in symptoms and unclear long-term risk. Detailed Case Description We describe a case of a 27 year old, healthy woman, with a long-standing history of loose stools, up to 8 bowel movements per day, and bloating. After diagnostic workup including lactose-breath test, celiac screen, microbiologic, and endocrinologic work up as well as colonoscopy for microscopic colitis; the presumptive diagnosis was irritable bowel syndrome (IBS) - diarrhea subtype. Her colonoscopy revealed normal biopsies of the cecum, transverse colon; however, the rectum contained a well demarcated, erythematous region of approximately 1 inch diameter, adjacent to a prominent fold and resembling a flat polyp. Pathologic biopsy of the folds identified benign gastric mucosa and benign large intestinal mucosa respectively. The diagnosis of rectal GHT was made based on the presence of gastric oxyntic mucosa with chief, parietal, and foveolar cells. Hpylori was not seen. The patient's IBS was treated with diet and lifestyle intervention. Loperamide was used to reduce stool frequency. Repeat sigmoidoscopy 2 years later confirmed stable GHT in rectum. The patient responded well to a reduced gluten diet, and had resolution of her longstanding IBS. She remains stable 8 years after diagnosis with no active IBS symptoms, and no clinical concerns about her GHT. Discussion GHT distal to the foregut is believed to be caused by pluripotent stem cells abnormally differentiating into gastric mucosa. Common symptoms of GHT include abdominal pain and gastrointestinal bleeding but many cases are asymptomatic. A literature review demonstrates higher prevalence in males with a younger median age at diagnosis. Complications are more common in the pediatric population, while risk of malignant transformation is higher in adults. Treatment is with H2-receptor antagonists or proton-pump inhibitors for bleeding, or complete excision for refractory symptoms. Few cases of neoplastic changes are reported in the literature but further observation is needed to appreciate the risk and benefit of pre-emptive excision by surgery or endoscopic submucosal dissection.1614 Figure 1. Heterotopic gastric tissue in rectum