Polyp removal is recommended to decrease the risk of colorectal cancer. Repeat colonoscopy should be performed every 1–2 years. If polyps are very large, numerous, or increase in number rapidly, then surgery may be necessary. Surgery may also be warranted if CRC is suspected or confirmed. First-degree relatives of people with SPS have an increased risk of CRC, and should undergo early screening with colonoscopy. Types
SPS may occur with one of two phenotypes: distal or proximal. The distal phenotype may demonstrate numerous small polyps in the distal colon (sigmoid) and rectum, whereas the proximal phenotype may be characterized by relatively fewer, but larger polyps in the proximal colon (cecum, ascending colon, etc.). Individuals meeting only criterion 3 from 2010 criteria, or only criterion 2 from the 2019 classification, have a distal phenotype have a lower risk of CRC compared with the proximal phenotype. Signs and symptoms
Serrated polyposis syndrome often does not cause symptoms. The risk of colon cancer is between 25 and 40%.Sessile serrated polyps, as seen during endoscopy or colonoscopy, are flat (rather than raised) and are easily overlooked. Serrated lesions range in size from small (<5 mm) to large, and often have a "mucous cap" overlying the polyp. Serrated lesions are frequently located on the folds of the colon (haustral folds). Pathophysiology
SPS is not caused by a single gene mutation. Several genetic abnormalities are associated with the condition, and a familial or inherited pattern may occur. Key genetic abnormalities include mutations in BRAF, abnormal CpG island methylator phenotype, and microsatellite instability.
History
The condition was originally known as hyperplastic polyposis syndrome. When the syndrome was first recognized, only hyperplastic polyps were included in its definition, and the syndrome was believed to not be associated with a higher risk of colorectal cancer. In 1996, a case series revealed an association of the syndrome with cancer and serrated adenomas. Subsequently, other types of serrated polyps were found to occur in this condition, so the name was adjusted to the present "serrated polyposis syndrome. "The World Health Organization released diagnostic criteria in 2010, which were updated in 2010 and again in 2019. The 2010 classification defined SPS as meeting any of the following criteria: 1) five or more serrated polyps proximal to the sigmoid colon with 2 larger than 10 mm in size, 2) any serrated polyps found proximal to the sigmoid colon in a person with a first-degree relative with serrated polyposis, or 3) more than 20 serrated colon polyps. The updated 2019 classification revised the first criterion to include lesions in the sigmoid colon, and excluded very small polyps (<5 mm). The updated 2019 classification also removed the criterion that included any serrated lesions proximal to the sigmoid colon in a person with a first degree relative with SPS. Epidemiology
Data regarding overall prevalence of SPS is lacking, but it is estimated to occur in roughly 1 in 100,000. SPS is equally common among men and women. Most individuals with SPS are diagnosed between 40 and 60 years of age, with an average age of 55 years.