Serrated polyposis syndrome

Serrated polyposis syndrome (SPS), formerly known as hyperplastic polyposis syndrome, is a condition characterized by the development of multiple serrated polyps throughout the colon and rectum. Serrated polyps include hyperplastic polyps, sessile serrated lesions (formerly sessile serrated adenomas/polyps), and traditional serrated adenomas. The condition is defined by the World Health Organization (WHO) criteria, which include having at least five serrated polyps proximal to the sigmoid colon (with two or more being ≥10 mm in size), any number of serrated polyps proximal to the sigmoid colon in an individual with a first-degree relative who has serrated polyposis, or more than 20 serrated polyps of any size distributed throughout the colon. SPS primarily affects the gastrointestinal system, specifically the large intestine. Patients with this syndrome have an increased risk of developing colorectal cancer, estimated to be significantly higher than the general population. The serrated neoplasia pathway, through which these polyps can progress to cancer, involves distinct molecular mechanisms including CpG island methylator phenotype (CIMP), BRAF mutations, and microsatellite instability. Many patients are asymptomatic and are diagnosed incidentally during screening colonoscopy, though some may present with rectal bleeding, changes in bowel habits, or abdominal discomfort. The primary management of serrated polyposis syndrome involves regular colonoscopic surveillance with removal of all polyps larger than 5 mm. Surveillance colonoscopy is typically recommended every one to three years, depending on polyp burden and individual risk factors. In cases where polyps are too numerous to manage endoscopically, or when high-grade dysplasia or cancer is detected, surgical intervention such as colectomy may be necessary. Genetic counseling is recommended for affected individuals and their first-degree relatives, who should undergo screening colonoscopy. Although specific genetic causes have been identified in some families, including associations with RNF43 gene mutations, the genetic basis remains incompletely understood in most cases.

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