Sessile serrated adenoma

Sessile Serrated Adenoma (SSA) is a type of polyp found in the colon or rectum. It is considered a precursor lesion to colorectal cancer, specifically microsatellite unstable colorectal cancer.

Overview

SSAs are characterized by their flat or slightly elevated appearance and their serrated or "saw-tooth" histological pattern. They are typically found in the right colon and are often larger than other types of adenomas. SSAs are associated with the serrated polyp pathway, which is thought to be responsible for approximately 15-30% of all colorectal cancers.

Histology

The histological features of SSAs include a serrated architecture, characterized by elongated crypts and horizontal crypt bases. The crypts often show a "boot" or "anchor" shape. The surface of the polyp is typically covered with a layer of mucin, which can make it difficult to detect during a colonoscopy.

Clinical Significance

SSAs are considered to be precursors to colorectal cancer, particularly microsatellite unstable colorectal cancer. This type of cancer is often more aggressive and has a poorer prognosis than other types of colorectal cancer. Therefore, early detection and removal of SSAs is crucial in preventing the development of colorectal cancer.

Diagnosis

Diagnosis of SSAs is typically made during a colonoscopy. However, due to their flat appearance and the layer of mucin that often covers the surface, they can be difficult to detect. Special techniques, such as narrow band imaging or chromoendoscopy, may be used to improve detection rates.

Treatment

The primary treatment for SSAs is endoscopic removal during a colonoscopy. In some cases, if the polyp is large or located in a difficult-to-reach area, surgery may be required.

See Also

• Adenoma
• Colorectal cancer
• Colonoscopy
• Polyp