A stomach polyp or gastric polyp is a mass or growth in the layers of the stomach that protrudes above the surface of the surrounding mucosa (stomach lining). A stomach polyp has the potential to become cancerous – most will remain benign but in a minority of cases it will progress into cancer.
Overall, a stomach polyp is a rare condition when compared to other gastric conditions. Most stomach polyps are less than 1 centimeter in diameter and due to inflammation or hyperplasia (explained below). Larger stomach polyps, greater than 1.5 centimeters in diameter, are associated with a greater risk of malignancy (cancer) and if the polyp is larger than 2 centimeters in diameter, it is usually removed immediately.
Types of Stomach Polyps
Most stomach polyps occur due to inflammation or hyperplasia of the epithelium or deeper layers. Overgrowth of tissue (hyperplasia) in the stomach lining occur as a result of repeated inflammation. There are usually multiple hypertrophic polyps present simultaneously which appear oval in shape with a smooth surface. Sometimes the polyp is ulcerated, similar to a peptic ulcer, although this is usually superficial. Microscopic examination of the polyp reveals significant edema (swelling) in the lamnia propria layer and it is not uncommon for the mucosa around the polyp to also be inflamed.
Fundic Gland Polyps
Also known as fundic cystic gland polyps, these stomach polyps arise as a result of a cyst-like dilation of the glandular tissue of the stomach lining. The growth is typically lined by flattened parietal and chief cells – refer to Gastric Acid Secretion for more information on these stomach cells. The tissue of the polyp as well as the surrounding tissue are usually not edematous and inflamed.
Adenomas are a less common type of gastric polyp (10% of cases) and is most commonly found in the antrum of the stomach. These types of polyps are composed of abnormal intestinal-type columnar epithelium. The level of dysplasia of these cells may be low or high grade. Adenomas are the most likely type of stomach polyp to become cancerous. The risk of malignancy is linked to its size – polyps larger than 2 centimeters in diameter are of a higher risk.
Causes of Stomach Polyps
The most common cause of stomach polyps is chronic gastritis. Persistent irritation of the stomach lining triggers excessive growth of normal cells (hyperplasia). If the gastritis is a result of long term H.pylori infection, successful eradication and appropriate treatment of H.pylori gastritis may lead to the polyp resolving spontaneously. Most cases of gastritis that lead to a polyp formation will result in a hypertrophic polyp.
Fundic Gland Polyps
This is often linked to an inherited condition known as familial adenomatous polyposis (FAP). However the rise in fundic gland polyps in recent years may be linked to long term use of proton pump inhibitors which may result in increased gastrin secretion and hyperplasia of the glandular tissue.
An adenoma is more likely to occur in cases of chronic H.pylori gastritis or autoimmune gastritis that progress to atrophic gastritis (destruction of the stomach lining as a result of chronic inflammation). A family history of familial adenomatous polyposis (FAP) also increases the incidence of an adenoma.
Signs and Symptoms of Stomach Polyps
Although a rare gastric condition, stomach polyps should be considered as a possible complication in chronic gastritis. The signs and symptoms often associated with stomach polyps is usually due to the gastritis and not as a result of the polyp itself (Gastritis Symptoms). In the event of an ulceration of the polyp, the symptoms may also resemble a stomach ulcer (Stomach Ulcer Symptoms). Larger stomach polyps may result in a gastric outlet obstruction (Delayed Gastric Emptying Symptoms).