Colorectal polyps are common growths found on the inner lining of the colon or rectum during a colonoscopy. They represent a variety of tissue types, with some carrying a risk of developing into cancer and others being generally harmless. A pathology report may identify a specific type of growth called a hyperplastic polyp (HP).
What Defines a Hyperplastic Polyp
A hyperplastic polyp is a type of non-neoplastic growth, meaning it results from an overgrowth of normal cells rather than from abnormal cellular transformation. The term “hyperplasia” refers to this excessive multiplication of cells, which leads to a small protrusion of the mucosal lining. This is distinct from “neoplasia,” which describes the abnormal cell growth seen in precancerous polyps like adenomas.
These polyps are characterized by a microscopic pattern often described as a “serrated” or “sawtooth” shape, caused by the elongated and folded architecture of the crypts. The cells lining these crypts are mature and do not show the signs of cellular abnormality, or dysplasia, that mark a precancerous lesion. Hyperplastic polyps are the most common type of serrated polyp, accounting for approximately 75% of all polyps in this category.
Hyperplastic polyps are typically small, measuring less than 5 millimeters in diameter, and are usually sessile, meaning they are flat and lack a stalk. They are most frequently found in the lower part of the colon, specifically the distal colon and the rectum. Their small size and location help distinguish them from other, more concerning polyp types.
Hyperplastic Polyps and Cancer Risk
The vast majority of hyperplastic polyps are considered non-neoplastic and carry virtually no risk of developing into cancer. When a pathologist confirms a polyp as a true hyperplastic polyp, it is generally not a cause for concern regarding malignant potential. This is a significant finding for patients, as many other types of polyps, known as adenomas, are considered precancerous lesions that can progress to colorectal cancer over time.
The main challenge lies in the fact that hyperplastic polyps can look similar to other, more dangerous serrated lesions during a colonoscopy. Specifically, they must be distinguished from sessile serrated lesions (SSLs), which were previously sometimes misclassified as hyperplastic polyps. SSLs are now recognized as having malignant potential and are precursors to a significant portion of colorectal cancers.
This need for precise differentiation means that the pathologist’s microscopic analysis is the determining factor in assessing risk. While small hyperplastic polyps found in the distal colon are almost universally benign, the risk profile can change based on size and location. Larger hyperplastic polyps, particularly those 10 millimeters or greater, or those found in the proximal (right) side of the colon, are often treated with greater scrutiny.
A large hyperplastic polyp in the proximal colon may be reclassified as an SSL due to the rare possibility of malignant transformation in that area. This practice highlights the importance of the final pathology report, which guides the subsequent risk assessment and surveillance plan.
Follow-up and Long-Term Monitoring
When a colonoscopy finds only small hyperplastic polyps (typically less than 10 millimeters) located in the distal colon, the finding usually does not change the standard surveillance interval. For most patients, this means returning to the screening schedule recommended for an average-risk individual, which is a colonoscopy every 10 years. This reflects the benign nature of these common growths.
The polyps are removed during the initial procedure, known as a polypectomy, even though they are considered harmless. Removal ensures the pathologist can accurately classify the lesion and eliminates any possibility of future growth or confusion with a higher-risk polyp. Following the removal of small, distal hyperplastic polyps, the patient is essentially considered to have had a normal colonoscopy for the purposes of future scheduling.
The surveillance interval shortens if multiple or larger polyps are found, even if they are hyperplastic. If a patient has a hyperplastic polyp that is 10 millimeters or larger, a follow-up colonoscopy is typically recommended in 3 to 5 years. This more intensive schedule is also applied if a patient has many hyperplastic polyps, as this could be an indication of serrated polyposis syndrome, which carries a higher cancer risk.
Follow-up recommendations are always individualized, taking into account the polyp’s size, exact location, and the presence of other polyps or risk factors. Current guidelines assume a high-quality initial colonoscopy was performed, including complete examination and full removal of the polyps. A personalized surveillance plan is then created to balance monitoring for new growths with minimizing the risks associated with frequent procedures.