Polyps are abnormal growths of tissue that can develop on mucous membranes throughout the body. While many are benign, meaning non-cancerous, their presence often warrants medical attention. Understanding their characteristics, particularly size, is important for medical evaluation and guiding appropriate follow-up care.
Understanding Polyps
Polyps originate from the abnormal multiplication of cells, forming a projection from a mucous membrane. These growths are commonly found in various parts of the body, including the colon, stomach, nose, and uterus. Some polyps may develop due to inflammation or irritation.
Most polyps are harmless and do not cause symptoms, especially when small. However, because they result from abnormal cell growth, some polyps have the potential to change over time. They can be attached by a narrow stalk, known as pedunculated, or grow flat against the surface, referred to as sessile.
Defining Polyp Size
Medical professionals classify polyps by size using millimeters (mm). Polyps 5 mm or less are typically considered diminutive or small. Those between 6 and 9 mm are often categorized as medium-sized.
A polyp is generally classified as “large” when it measures 10 mm (1 centimeter) or greater in diameter. This 10 mm threshold is a widely recognized point that distinguishes polyps requiring closer attention. While some medical contexts may refer to polyps 20 mm or larger as “very large” or “complex,” 10 mm remains a key indicator of a larger growth.
Why Polyp Size Matters
The size of a polyp is an important factor in assessing its potential health implications. Larger polyps are associated with an increased likelihood of containing advanced dysplasia or progressing to cancer. The risk of a polyp becoming cancerous significantly rises once it exceeds 10 millimeters.
Adenomatous polyps, a specific type found in the colon, are considered pre-malignant, meaning they have the potential to develop into colorectal cancer. The risk of malignancy in these adenomas correlates directly with their size. For polyps larger than 20 millimeters, the chance of being cancerous can range from 30% to 50%. Different growth patterns, such as villous adenomas, which tend to be larger and grow in an uneven pattern, also carry a higher risk compared to smaller, tubular adenomas.
What Happens After Detection
Once a polyp is detected, especially a large one, its removal is the typical next step. This procedure, called a polypectomy, is often performed during an endoscopy, such as a colonoscopy for colon polyps. After removal, the polyp is sent to a laboratory for detailed analysis by a pathologist to determine if the growth is non-cancerous, precancerous, or cancerous.
The characteristics of the removed polyp, including its size, type, and any concerning features, guide subsequent follow-up care. Individuals with a history of polyps, particularly larger ones or those with advanced features, typically require regular surveillance. This involves periodic repeat endoscopies to monitor for new polyp formation or recurrence, helping to detect changes early and reduce the risk of cancer development.