A juvenile polyp is a growth that projects from the lining of the intestine and originates in the tissues supporting that lining. It does not arise from the colonocytes (colonic lining cells) themselves but from the tissues underneath the lining cells. It is not neoplastic but hamartomatous. A hamartoma is a growth that arises from normal tissues. It is self-limiting and benign.
Juvenile polyps are relatively common in children. To look at, they are bright red. They present with bleeding, or, if they are in the lower rectum, they may prolapse outside the anus.
Juvenile polyps can be solitary or multiple. Multiple juvenile polyps (more than five) are termed Juvenile Polyposis.
Juvenile Polyposis may or may not be familial. Familial Juvenile Polyposis has been associated with mutations in two genes: SMAD4 on chromosome 18 and PTEN on chromosome 10. It has been estimated that SMAD4 mutations account for 25 percent of Juvenile Polyposis families. Testing for mutations in this gene is only available for research purposes. When commercially available, gene testing can be offered to families with Juvenile Polyposis. If a mutation is found, testing can be offered to relatives who are at risk of developing this condition.
Juvenile Polyposis can cause polyps in the large intestine, small intestine and stomach. Usually, colorectal polyps are the ones that cause symptoms, such as bleeding, diarrhea, abdominal cramps and anemia.
In such cases, several types of operations can be performed, which are the same ones offered to patients with familial adenomatous polyposis. These include colectomy and ileorectal anastomosis, proctocolectomy and pouch, or proctocolectomy and ileostomy.
There is a small but significant risk of cancer in patients with Juvenile Polyposis, mostly due to development of adenomatous tissue in juvenile polyps. This is reason to offer surgery when there are too many polyps to treat endoscopically.
Recommendations for screening a patient with Juvenile Polyposis include an upper and lower endoscopy every year with removal of colonic polyps and any large upper intestinal polyps. If no polyps are seen, the examinations can be done less often (every two to three years). In at-risk relatives with no genetic information, screening should start in their late teens. Genetic testing is not a common practice since it is still considered a research tool.