Additional implicated genes include: SMAD4, BMPR1A, PTEN, GREM1, and MUTYH. The only validated genetic cause of SPS is RNF43. However, most individuals with SPS do not have a germline mutation in any of the associated genes, including RNF43. As the underlying genetic risks for SPS are not fully understood, genetic testing is not recommended. Both autosomal dominant and autosomal recessive patterns of inheritance have been reported, as well as sporadic. Individuals with SPS have serrated polyps, which include hyperplastic polyps, traditional serrated adenomas, and sessile serrated polyps. In addition to serrated polyps, adenomas are often identified. Diagnosis
The diagnosis of serrated polyposis syndrome is achieved when either one of two criteria are met: ≥5 serrated lesions/polyps proximal to the rectum (all ≥ 5 mm in size, with two lesions ≥10 mm), or >20 serrated lesions/polyps of any size distributed throughout the large bowel with 5 proximal to the rectum. Any serrated polyp is counted towards the diagnosis, including sessile serrated lesions, hyperplastic polyps, and traditional serrated adenomas. In addition, the cumulative number of serrated lesions is cumulative over time and includes multiple colonoscopies. The diagnosis of SPS is often overlooked, and requires lifelong tracking of cumulative serrated polyps. Treatment
Colonoscopy is the mainstay of treatment for SPS, which allows for the identification of polyps and removal. Polyp removal is recommended to prevent the development of colorectal cancer. If polyps are relatively few, then removal may be achieved with colonoscopy. After polyps are removed, repeat colonoscopy is recommended in 1 to 3 year intervals.
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.