by Jason Wasserman, MD FRCPC, updated on June 1, 2020
The stomach is a hollow organ located in the middle of your abdomen. The stomach is responsible for breaking down and absorbing food so that it can be used by your body.
The inner surface of the stomach is lined by specialized cells called foveolar cells which form a barrier called an epithelium. This barrier protects the stomach from the acid that aids in the digestion of our food.
Inflammation within the lining of the stomach is called gastritis. Inflammation that is new or that is causing on going damage is called active inflammation. Inflammation that has been present for a long period of time is called chronic inflammation. Depending on the cause, both active and chronic inflammation can be seen in the stomach at the same time.
Inflammation can damage the normal foveolar epithelium that lines the inside of the stomach. The epithelium will respond by creating new cells to replace the ones that were damaged or lost. However, the repair process can sometimes lead to too many new cells being created. An increased number of cells is called hyperplasia.
A hyperplastic polyp is a non-cancerous growth made up of cells normally found in the epithelium lining the inside of the stomach. It is called a polyp because it often sticks out from the surface of the tissue.
Hyperplastic polyps are also called inflammatory polyps. Both polyps are thought to represent a spectrum of ongoing inflammation (inflammatory polyp) and regeneration/repair (hyperplastic polyp).
Anything that causes gastritis in the stomach can lead to the development of a hyperplastic polyp. The most common causes of gastritis are infection, bile reflux, and autoimmune gastritis.
The most common cause of active gastritis is infection of the stomach by a bacteria known as Helicobacter. Pathologists often use tests called special stains or immunohistochemistry that make it easier to see the small Helicobacter organisms.
Chronic gastritis that is not treated can damage the foveolar epithelium. If the damage continues for many years, a new type of epithelium similar to the epithelium normally found in the small intestine slowly replaces the foveolar epithelium.
The change from foveolar epithelium to small intestinal epithelium is an example of metaplasia. This specific type of metaplasia that takes place in the stomach is referred to as intestinal metaplasia.
Intestinal metaplasia may be found in some hyperplastic polyps. If the pathologist sees intestinal metaplasia in your tissue sample, it will be described in your report.
For most patients, hyperplastic polyps are unrelated to any preexisting genetic condition. Some patients, however, inherit genetic changes that put them at a higher risk of developing multiple hyperplastic polyps as well as other non-cancerous growths.
These patients are said to have a syndrome and the most common syndromes associated with hyperplastic polyps are Peutz-Jeghers, Cowden, and Juvenile polyposis.
In these syndromes, specific genes that normally prevent our cells from growing and dividing too rapidly or in an uncontrolled way, are altered or mutated. This causes uncontrolled cell growth and the development of a non-cancerous polyp.