Ectopic Gastric Mucosa (EGM) is a medical condition defined by the presence of normal stomach lining tissue located outside of the stomach itself. This abnormal placement is classified as a congenital anomaly, meaning it develops before birth. The term “ectopic” signifies the tissue is in an unusual location, while “gastric mucosa” refers to the specialized lining of the stomach. Although structurally normal, its presence in an uncharacteristic site can lead to various symptoms and complications.
What Ectopic Gastric Mucosa Is
The tissue found in EGM is structurally identical to the normal lining of the stomach, containing the specialized cells responsible for gastric function. This misplaced lining includes mucous cells, chief cells, and parietal cells. Parietal cells secrete hydrochloric acid, while chief cells secrete pepsinogen, the precursor to the digestive enzyme pepsin.
This condition is a form of heterotopia, where a small mass of otherwise normal tissue develops in an incorrect body location. The prevailing theory suggests EGM results from a failure in the complex developmental processes of the embryonic gut tube. During early development, cells destined to form the stomach lining mistakenly migrate or persist in other areas of the gastrointestinal tract or surrounding structures.
The problem with EGM is functional, not structural, as the misplaced cells continue to perform their intended stomach roles. The parietal cells secrete hydrochloric acid and the chief cells release pepsin into organs not equipped to handle these digestive agents. Since surrounding tissues lack the protective mucous barrier of the stomach, the acid and enzyme secretions can cause irritation, inflammation, and ulceration.
Common Locations and Clinical Manifestations
Ectopic gastric mucosa can appear anywhere in the gastrointestinal tract, but two locations are the most common sites. The upper esophagus is the most frequent site, often referred to as an “Inlet Patch.” This patch appears as a salmon-pink area just below the pharynx and is typically an incidental finding during an upper endoscopy, remaining asymptomatic in many individuals.
When esophageal EGM causes issues, symptoms often mimic chronic reflux or involve irritation of the throat and larynx. Patients may experience persistent coughing, hoarseness, a feeling of a lump in the throat, or difficulty swallowing (dysphagia). This results from acid secretion irritating the sensitive, non-gastric lining of the esophagus.
The second most common site for EGM is within the small intestine, specifically in a congenital pouch called a Meckel’s Diverticulum. This diverticulum is the most common congenital anomaly of the small bowel, and approximately half of the cases contain ectopic tissue, most often gastric mucosa. EGM here is the primary cause of complications associated with Meckel’s Diverticulum, particularly in pediatric patients.
The acid and pepsin secreted into the small intestine can cause ulceration in the adjacent intestinal lining, leading to the most common presentation: painless gastrointestinal bleeding. Less frequently, inflammation from the ulceration can trigger an obstruction or perforation of the bowel wall, requiring surgical intervention. EGM has also been reported in rare locations, including the gallbladder, larynx, rectum, and umbilicus.
Recognizing the Symptoms and Diagnostic Procedures
The symptoms of EGM are highly variable, depending on the location and amount of acid secretion, ranging from none to severe bleeding. Gastrointestinal bleeding, pain, and obstruction are the primary reasons for seeking medical attention, especially when EGM is located in the small bowel. In the esophagus, symptoms like chronic throat clearing, persistent cough, or burning chest pain can prompt investigation.
Doctors rely on visualization and tissue sampling to definitively diagnose the condition. Endoscopy, such as an esophagogastroduodenoscopy (EGD) or a colonoscopy, allows a physician to view the abnormal tissue directly. EGM typically appears as a distinct, reddish-pink patch that contrasts with the surrounding pale mucosa.
A biopsy of the suspect tissue is necessary for a conclusive diagnosis. The sample must be analyzed under a microscope (histopathology) where the pathologist confirms the presence of gastric glands, including parietal and chief cells. For detecting EGM in the small intestine, particularly in Meckel’s Diverticulum, a specialized nuclear medicine test called a Technetium-99m pertechnetate scan is utilized.
This scan works because the radioisotope is actively absorbed by the acid-secreting parietal cells in the ectopic gastric tissue. The technique allows the misplaced stomach lining to be visualized on an image, helping to locate the source of bleeding in the small bowel. These tools confirm EGM and rule out other conditions that can cause similar symptoms, such as chronic inflammation or tumors.
Treatment Approaches and Management
The management of ectopic gastric mucosa is tailored to the tissue’s location, symptom severity, and the presence of complications. For cases where EGM is found incidentally and causes no symptoms, a conservative approach of watchful waiting is recommended.
When symptoms are present, the first-line medical approach is to suppress acid production from the ectopic tissue. Proton Pump Inhibitors (PPIs) are effective medications that block the final stage of acid production in the parietal cells. Daily use of a PPI can reduce irritation and inflammation in the esophagus, leading to the resolution of symptoms like cough or dysphagia.
For symptomatic EGM in the esophagus that does not respond adequately to medical therapy, endoscopic treatment options are available. Procedures like Argon Plasma Coagulation (APC) or Radiofrequency Ablation (RFA) destroy the misplaced gastric tissue with heat energy. These techniques aim to remove the source of acid secretion and allow the esophageal lining to heal.
Surgical intervention is reserved for EGM causing severe complications, most notably in Meckel’s Diverticulum. If the ectopic tissue leads to major gastrointestinal bleeding, bowel obstruction, or perforation, surgical resection of the affected segment of the small intestine is necessary. This approach removes the abnormal tissue and the high-risk segment of the bowel, resolving the complication and preventing recurrence.