A fundic gland polyp (FGP) is a common, non-cancerous growth that forms on the inner lining of the stomach. These growths originate in the fundus and body of the stomach, which are the upper and middle sections where acid-secreting glands are located. FGPs are the most frequently encountered type of gastric polyp, with estimates suggesting they are found in up to 6% of patients undergoing an upper endoscopy.
The discovery of these polyps is often an incidental finding during a routine procedure for an unrelated symptom, such as reflux or dyspepsia, since they rarely cause any noticeable problems. While the word “polyp” can sound alarming, the vast majority of FGPs are benign and do not pose a serious health risk. The primary concern for a physician is determining the underlying cause, as this dictates the need for further investigation and management.
The Two Primary Types of Fundic Gland Polyps
Fundic gland polyps are broadly categorized into two main groups based on their cause: sporadic and syndrome-associated. Distinguishing between these two types is important because they carry very different implications for a patient’s overall health and future risk.
Sporadic FGPs are the most common type, often appearing as small, numerous, and isolated findings. These polyps are frequently linked to the long-term use of Proton Pump Inhibitors (PPIs), a class of medications used to reduce stomach acid. This association is so common that they are sometimes referred to as medication-associated polyps.
The mechanism linking PPIs to FGP development involves the body’s natural response to reduced stomach acid. Long-term acid suppression leads to an increase in the hormone gastrin, causing hypergastrinemia. Gastrin promotes growth in the stomach’s acid-producing cells, resulting in the overgrowth and cystic dilation of the fundic glands. The number and size of these PPI-related FGPs can be proportional to the dose and duration of the medication.
In contrast, syndrome-associated FGPs are a marker for a serious underlying hereditary condition, most often Familial Adenomatous Polyposis (FAP). FAP is a genetic disorder characterized by the development of numerous polyps in the colon, carrying a high risk of colorectal cancer if untreated. FGPs associated with FAP are typically more numerous than sporadic polyps, sometimes carpeting the entire stomach, and often appear in younger patients.
The genetic difference between the two types is also notable; sporadic FGPs often have a mutation in the \(\beta\)-catenin gene, while FAP-associated FGPs are linked to a mutation in the Adenomatous Polyposis Coli (APC) gene. When a patient is found to have multiple FGPs, especially at a young age, the possibility of FAP must be investigated immediately.
Symptoms and Malignancy Risk
Fundic gland polyps rarely produce symptoms and are usually detected incidentally during an upper endoscopy. When symptoms do occur, they are typically associated with very large polyps, which are rare, or are related to the underlying condition that prompted the procedure. Larger polyps, those exceeding one centimeter, may occasionally cause minor bleeding leading to anemia, or, in extremely rare cases, obstruction.
The potential for cancer development is the most important question regarding any polyp. For sporadic FGPs, including those caused by PPI use, the risk is extremely low. They are considered benign and have virtually no malignant potential; less than one percent show low-grade dysplasia, a mild form of abnormal cell growth.
The risk profile changes significantly for polyps associated with FAP. FAP-associated FGPs are more likely to contain dysplasia and can progress to gastric cancer, though this remains uncommon. The presence of dysplasia necessitates rigorous surveillance for these patients. Dysplasia within any FGP is the primary exception to the rule of benignity and requires careful pathology review.
Diagnosis and Clinical Management
Identifying a fundic gland polyp requires an upper endoscopy, allowing the physician to visually inspect the stomach lining. The definitive diagnosis relies on removing a small tissue sample (biopsy) for microscopic examination. This review confirms the type of polyp and, critically, checks for the presence of dysplasia or abnormal cells.
Management decisions are tailored specifically to the FGP’s cause and characteristics. For the common sporadic or PPI-associated FGPs that are small and non-dysplastic, the standard recommendation is conservative management, which means no removal is needed. If the polyp is suspected to be related to PPI use, the physician may discuss discontinuing the medication, if medically appropriate, to see if the polyps shrink or disappear, which often happens within a few months.
Polyps are generally only removed if they exhibit high-risk features, such as being larger than one centimeter, causing bleeding, or containing dysplasia. For patients whose FGPs suggest a possible underlying hereditary condition like FAP, a more aggressive management plan is required. This typically involves a colonoscopy to screen for colorectal polyps and regular endoscopic surveillance of the stomach to monitor the FGPs for any signs of progression.