Editors Note: Ophanet annually publishes the prevalence of rare diseases; this report series begins with the most prevalent.
Individuals are diagnosed with hyperplastic polyposis when they have multiple hyperplastic polyps, usually greater than 20 polyps. The number of polyps ranges anywhere from 6 to greater than 100, though most individuals with hyperplastic polyposis have between 40 and 100 polyps. A diagnosis of Hyperplastic polyposis may also made in individuals who present with fewer than 20 hyperplastic polyps, but whose polyps are larger, often greater than 2 centimeters. Individuals may also be diagnosed with multiple serrated adenomas or a mix of both serrated adenomas and hyperplastic polyps. Hyperplastic polyposis is usually diagnosed in individuals in their 40’s to 60’s, though it has been reported in individuals as young as 11 years old. Individuals with hyperplastic polyposis are at an increased risk for developing colorectal cancer, so routine screening is extremely important. Although the genetic basis for FAP, HNPCC, Peutz-Jeghers, MYH-Associated Polyposis, and juvenile polyposis has been identified, hyperplastic polyposis has not yet been explained. Hyperplastic polyposis is suspected to have a familial basis and reports have shown that is inheritable in 5% of cases, though the exact mechanism of inheritance has not been identified.