10 Common Colon Polyp Types

A polyp is a growth on a mucous membrane. While colon polyps develop on the lining of the colon, they can also appear in nasal passages, the mouth, the uterus and genital area, and the bladder. Most colon polyps are benign, but some can grow abnormally and become cancerous. Colon polyps can present in two distinct shapes and four different types. Understanding these variations is crucial for identifying which polyps may pose a cancer risk and which are benign.

1. Pedunculated polyps

Pedunculated polyps are a form of colon polyp characterized by their raised growths attached to the mucous membrane via a long stalk, resembling a mushroom with a bulbous top and a stem. These polyps are easily identifiable due to their noticeable projection into the colon space. While their general structure remains consistent, minor variations can occur based on the specific polyps' type. To accurately determine the type of polyp, medical testing is required.

2. Sessile polyps

Sessile polyps are a type of colon polyp that are more challenging to detect due to their flat appearance on the mucous membrane, lacking a stalk. These polyps are often missed during examinations because they blend into the lining more seamlessly compared to pedunculated polyps. Sessile polyps have a higher potential for developing into cancer, partly because they can remain undiagnosed for longer periods. Additionally, their removal typically necessitates surgical intervention due to their difficult-to-access nature.

3. Inflammatory colon polyp

An inflammatory colon polyp, often termed a 'false polyp,' is typically benign and carries a minimal risk of developing into cancer. These polyps are associated with Inflammatory Bowel Disease (IBD), including conditions such as Crohn's disease and ulcerative colitis, and are commonly detected in affected individuals. Among the various types of colon polyps, inflammatory polyps are considered the least intrusive. Although removal may be necessary, the probability of malignant transformation is very low.

4. Hyperplastic polyp

A common type of colon polyp is the hyperplastic polyp, characterized by its rapid abnormal tissue growth. Despite this accelerated cellular proliferation, these polyps are typically benign and pose a minimal risk of transitioning into cancer. They are often removed upon detection. Hyperplastic growth is not restricted to the colon; it can occur in various organs and tissues, and it is sometimes mistaken for a benign tumor.

5. Adenomatous polyp

An adenoma is a glandular structure that forms within tissue. Adenomatous colon polyps account for up to 70% of all colon polyps and can be either benign or malignant. When an adenoma transitions to a cancerous state, it is termed an adenocarcinoma. This transformation often occurs over many years, typically unnoticed by the patient. During this process, the growth loses its normal cellular structure and develops into a tumor.

6. Tubular Adenoma

A tubular adenoma is a type of adenoma characterized by its tubular cell pattern observed under a microscope. Unlike villous adenomas, tubular adenomas exhibit a different growth pattern. They are generally considered pre-malignant, with a significant likelihood of eventually becoming malignant. Therefore, it is advisable to remove tubular adenomas while they remain benign. If untreated, these adenomas can develop into colon cancer and potentially progress to rectal cancer.

7. Villous adenoma

A villous adenoma is a type of polyp with a high potential for malignancy if left untreated or undetected. Studies indicate that up to 30% of villous adenomas in the colon may progress to cancer. Characterized by its cauliflower-like appearance with distinct protrusions, this adenoma is composed of columnar epithelial cells that typically line cavities, organs, and blood vessels. Due to their potential to grow significantly and become obstructive, prompt removal from the colon lining is recommended.

8. Are colon polyps cancerous?

The diagnosis of cancerous colon polyps and adenomas involves several critical factors. Primarily, the size and type of the polyp or adenoma are assessed, followed by the evaluation of dysplasia, which refers to the proliferation of abnormal cells and tissue deformation within the structure. For instance, a 1.5-centimeter tubular adenoma carries a 2% risk of cancer, whereas a 3-centimeter villous adenoma poses a 25% cancer risk. Diagnostic procedures typically include a screening schedule to monitor the growth rate of these polyps and adenomas.

9. Symptoms of colon polyps

Colon polyps can be challenging to detect and diagnose due to their typically asymptomatic nature. Although one cannot see or feel them directly, they may manifest through alterations in bowel habits, such as constipation, diarrhea, dark or bright red stool, blood in the stool, and abdominal discomfort. These symptoms are also common to other medical conditions, making a precise diagnosis essential. Colon polyps are usually identified through colorectal examinations, including colonoscopy, sigmoidoscopy, barium enema, or fecal occult blood tests. If you experience these symptoms for more than a week, it is advisable to consult your physician. In cases where the polyps are large, they might obstruct the colon and cause rectal bleeding.

10. Treatment for colon polyps

If you are over the age of 50, it is advisable to undergo a colorectal screening. Polyps larger than one centimeter should be removed to prevent potential malignancies. Such polyps can be excised during a colonoscopy and subsequently analyzed in a laboratory to ascertain if they are cancerous. Larger polyps may require surgical removal. Should cancer be detected, treatment options such as radiation therapy and chemotherapy will be considered based on the cancer's location and severity.