Polyps are abnormal tissue growths that can form on the inner lining of various organs within the body. While they can appear in places like the stomach, nose, or uterus, they are most commonly found in the colon and rectum. These growths can vary in size and shape, and some may remain harmless, while others have the potential to develop into cancer over time.
A sessile polyp is a type of growth that is directly attached to the tissue with a broad base, rather than a thin stalk. This distinguishes them from pedunculated polyps, which are often described as mushroom-like due to their stalked appearance. Understanding the nature of sessile polyps is important, as their attachment and characteristics can influence their detection and management.
Characteristics of Sessile Polyps
Sessile polyps are characterized by their flat or dome-shaped appearance, adhering directly to the mucous membrane of an organ. This broad-based attachment can make them less conspicuous than pedunculated polyps, which project into the organ’s lumen. They may blend in with the surrounding tissue, making them more challenging to identify during examinations.
Sessile polyps are most frequently observed in the colon, particularly among individuals over 45 years old, but can also occur in other areas such as the stomach, bladder, or nasal passages. Microscopically, these polyps exhibit specific cellular structures that differentiate them from other types, influencing their growth and potential for change.
Different types of sessile polyps, such as sessile serrated adenomas (SSA/Ps), tubular adenomas, and villous adenomas, have distinct microscopic features. For instance, SSA/Ps have a characteristic saw-toothed appearance of their crypts, while villous adenomas may appear shaggy or cauliflower-like. These distinctions are important because they relate to the polyp’s biological behavior and progression potential.
Significance and Care
Sessile polyps are important because some types carry a higher potential for malignant transformation compared to other polyps. For instance, sessile serrated adenomas (SSA/Ps) and villous adenomas are concerning due to their increased risk of developing into colorectal cancer. About 20% to 30% of colorectal cancers are believed to arise from the serrated polyp pathway, with SSA/Ps being precursors in this process. Early detection and removal are therefore important for preventing cancer development.
Many sessile polyps do not cause symptoms, often discovered incidentally during routine screenings. The main method for detecting colorectal polyps is a colonoscopy, which involves inserting a flexible tube with a camera to visualize the colon’s lining. If polyps are found during the procedure, they can often be removed at the same time. Other detection methods include virtual colonoscopy and stool-based tests, but a colonoscopy is often recommended if abnormalities are identified.
The removal of sessile polyps, known as a polypectomy, can be performed using various endoscopic techniques. For smaller polyps, a cold snare polypectomy might be used, while larger sessile polyps may require techniques like hot snare polypectomy or endoscopic mucosal resection (EMR). EMR involves injecting a solution beneath the polyp to lift it, creating a cushion that facilitates its removal, often in pieces (piecemeal resection) for larger lesions. Endoscopic submucosal dissection (ESD) is another technique for very large polyps, aiming for en bloc (one-piece) removal.
Following polyp removal, regular follow-up screenings are important due to the potential for recurrence or the development of new polyps. The recommended surveillance interval depends on factors such as the size, number, and type of polyps removed, as well as their microscopic features. For instance, patients with certain types of adenomas or larger polyps may require more frequent colonoscopies. This ongoing surveillance helps ensure that any new growths are detected and addressed promptly, reducing the long-term risk of colorectal cancer.