Gastric polyps are distinct intraluminal projections of mucosa or submucosal tissue. These lesions represent proliferative growth that can contain the potential for malignant transformation. Gastric polyps have many subsets, the most commonly seen and described are the triad of gastric hyperplastic polyps (GHP) characterized by pronounced foveolar hyperplasia, fundic gland polyps (FGP) characterized by dilated and irregularly budded fundic glands predominantly lined by parietal cells with a smaller proportion of chief cells, and adenomatous polyps characterized by low-grade glandular dysplasia.
However, within the umbrella of gastric polyps also falls a much broader differential for the lesion including carcinoids (grouping of endocrine cells resulting in projecting lesion), infiltrative lesions (xanthomas, lymphoid proliferations), mesenchymal proliferations (gastrointestinal stromal tumors, leiomyoma, fibroid polyps), and hamartomatous lesions (Peutz-Jegher, Cowden’s, juvenile) all of which may produce a mucosal/submucosal protrusion appearing as a gastric polyp. It is difficult to discern the likely histopathology of a polyp from simple inspection via endoscopy, in most instances, biopsy and histopathologic evaluation are necessary to guide management.
The vast majority of gastric polyps are found incidentally on endoscopic investigation or autopsy, and as such, the cause of their formation is poorly understood. The development of GHPs is thought to be related to chronic inflammation commonly associated with H. pylori infection and atrophic gastritis. The association with H. Pylori stems from the finding that in many cases (70%), GHPs will regress within a year after eradication of H. Pylori infection, assuming no reinfection occurs. Less is known about the cause of FGPs. However, several studies have indicated an association with chronic PPI usage, which suggests that a mechanism involving gastric acid suppression may lie in the background of their development.
The most commonly associated risks for the development of adenoma include age and chronic inflammation/irritation of the tissue involved, which results in intestinal metaplasia and subsequent risk for malignant transformation typically attributed to acquired mutations involving the expression of p53 and Ki-67 genes. It is worth mentioning here that the finding of gastric adenoma in a young patient can be indicative of the presence of a more concerning underlying genetic condition, familial adenomatous polyposis (FAP), which merits further investigation.
The prevalence and distribution of gastric polyps vary widely between sources, but from the review of several high powered studies, the prevalence of gastric polyps in patients undergoing endoscopy was between 2% to 6%. Of those, GHPs represent 17% to 42%, FGPs represent 37% to 77%, adenomas represent 0.5% to1%, and malignant neoplasm represented approximately 1% to 2%. Gastric polyps are most likely to be found in the fundus and have an increasing prevalence associated with increased age. Distribution amongst the sexes varies widely in the literature. However, females are more likely to have FGPs, and males are more likely to have adenoma. Variation in diet and lifestyle across different populations contributes to the wide variations reported between studies.
The vast majority of gastric polyps are asymptomatic, with over 90% being found incidentally on endoscopy. The most common complaints associated with the finding of gastric polyps are dyspepsia, acid reflux, heartburn, abdominal pain, early satiety, gastric outlet obstruction, gastrointestinal bleed, anemia, fatigue, and iron deficiency. Only in rare circumstances would a physical exam be helpful in the finding of gastric polyps as most are less than 2cm in size.
As the majority of gastric polyps are asymptomatic or found incidentally, evaluation most commonly begins with some complaint of dyspepsia or the finding of anemia on routine CBC. It is possible to see gastric polyps on noninvasive imaging, e.g., computed tomography (CT) scan or magnetic resonance imaging (MRI), but only in the rare case of a very large polyp. The gold standard for evaluation for gastric polyps consists of esophagogastroduodenoscopy (EGD) performed by an experienced practitioner.
As it is difficult to discern the underlying histopathology of a gastric polyp from visualization under endoscopy alone, biopsy and en-bloc resection are required to guide management. It is well known that malignant potential increases with an increased size of the lesion, and as such, it is advised that all lesions greater than 10mm be removed by endoscopic mucosal resection (EMR). A more conservative approach taken by some practitioners suggests the removal of all polyps greater than 5mm. Prior to any manipulation of the mucosa, a dose of intravenous proton pump inhibitor is administered to reduce the acidity of the environment and improve hemostasis. In many cases following endoscopy with biopsy, a PPI is continued for 4 to 8 weeks to improve healing at the biopsy/resection sites. If pathology reveals H. Pylori infection, antibiotic therapy is initiated. When polyps are removed or biopsied, or there is a finding of gastritis, it is common for the endoscopist to perform concurrent gastric mapping to determine the etiology of gastritis involving mucosal biopsy via cold forceps at multiple locations within the stomach.
Management and follow up after biopsy is guided by the histopathologic findings of the polyps removed during EGD. For GHPs removed by EGD without finding of dysplasia, a single repeat EGD is recommended at 1 year of follow up. If H. Pylori is found in biopsies associated with GHP, then a repeat EGD is often performed in 3-6 months for repeat biopsy to confirm eradication of infection and to track the regression of gastric polyps. For FGP, if there is a history of chronic PPI use, then discontinuation when possible is recommended, and 1 year follow up EGD is performed when lesions greater than 5 to 10mm were found on initial EGD and to track response to therapy. The finding of adenoma on microscopic evaluation of gastric polyp indicates the need for 1 year follow up EGD. In a patient less than 40 years old where multiple adenomas are seen on EGD, extensive family history taking and colonoscopy is recommended to rule out FAP. If dysplasia or early adenocarcinoma is detected on microscopic evaluation of a gastric polyp, repeat EGD is performed at 1 year and again at 3 years from initial endoscopy.
Overall the finding of gastric polyps carries with it a good prognosis with some studies indicating a finding of malignancy in less than 2% of polyps investigated. Characteristics of polyps that indicate a poorer prognosis include large size, advanced age of the patient, and finding of multiple adenomas. It is known that the risk of finding dysplasia or malignancy increases greatly in lesions larger than 20mm, in older patients, and that the finding of multiple adenomas may indicate the presence of FAP which has a high risk for development of adenocarcinoma.
Gastric cancer is the third most common cause of death related to cancer worldwide. As gastric polyps can represent precancerous lesions, it is possible that with proper management of gastric polyps, this number may be reduced. Recommendations that may decrease a patient’s risk for developing gastric polyps include dietary and lifestyle changes including but not limited to: decreasing alcohol intake, cessation of smoking, decreasing dietary fat and increasing fiber intake.
Gastric polyps may be found during investigation and workup of patients’ complaints of weakness, fatigue, and dyspepsia and while they can contribute to these symptoms, they are nearly always incidental findings during endoscopic evaluation performed to rule out other gastric pathologies such as peptic ulcer disease, Barrett’s esophagus, delayed gastric emptying, etc. As such, the decision and responsibility of properly managing gastric polyps rest with the specialist. Guidelines such as those laid out by the American Society of Gastrointestinal Endoscopy (ASGE) are in place for this reason and can be applied to direct specialists when they encounter pathologies such as GHP, FGP, and adenomatous polyps.
Since the management of gastric polyps is directed by a specialty service, interprofessional communication between the gastroenterologist and the primary care clinician is essential to ensuring the appropriate information is conveyed to patients and that they receive the necessary follow up dependent on their specific pathology found during the endoscopic evaluation. [Level 1] Pathologists, anesthetists, nurses, and surgical technicians are involved in the diagnosis, treatment, and care for patients with gastric polyps. Thus, interprofessional collaboration is important in achieving optimal patient outcomes.
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