Chapter 414

The most common gastrointestinal tumor in children is the benign single juvenile polyp. Single juvenile polyps are relatively common and do not infer an increased risk of colorectal cancer at any age. In contrast, findings of 5 or more hamartomatous polyps, one or more adenomas, or abnormal dysplastic histology suggest a diagnosis of one of the rare hereditary colorectal cancer syndromes. A family history of early cancer or polyps affecting multiple relatives over several generations is also consistent with a hereditary cancer syndrome.

The manifestations or expression of hereditary colorectal cancer/polyposis syndromes can be highly variable within a given family. Most of these syndromes are autosomal dominant, with cancer-related symptoms expected in other family members. The age of presentation, polyp number, and distribution or the age of cancer development can differ among affected family members who carry the same gene mutation. New spontaneous germline mutations are seen in up to one third of newly diagnosed pediatric polyposis patients.

Adenomas are either sessile or pedunculated and can be difficult to differentiate from hamartomas by appearance at endoscopy. Adenomas are by definition dysplastic having disorganized epithelial proliferation, loss of goblet cells, cellular and nuclear atypia. Dysplasia proceeds from mild to severe with further loss of cell growth regulation and indicates the progression from adenoma to early adenocarcinoma. Polyps can have mixed histologic features of both hamartomas and adenomas. Finding an adenomatous polyp in a child or adolescent suggests the diagnosis of a hereditary adenomatous polyposis syndrome, all of which are associated with a substantial risk of colon or other cancers, so further evaluation and surveillance are mandatory.

Juvenile polyps are the most common gastrointestinal tumor during childhood and can be seen in up to 2% of children under the age of 10 years.1,2 These lesions can present with painless rectal bleeding during defecation, or may only present when the polyp prolapses through the anus. Colonic juvenile polyps can also present with colic-like abdominal pain, diarrhea, or unexplained iron deficiency anemia. Juvenile polyps typically present from 2 to 4 years of age but can be found at any time during childhood or adolescence. Most juvenile polyps are solitary and are found in the rectosigmoid colon. Smaller polyps appear as flat sessile mucosal elevations that with time grow into mushroom-like pedunculated lesions. Juvenile or inflammatory polyps are classified as hamartomas. Pathology reveals an overgrowth of mature orderly epithelium with dilated mucus-filled glands, varying numbers of inflammatory cells, and surface ulceration. At times, the inflammation seen in juvenile polyps described as reactive atypia can be indistinguishable from early dysplasia.

### Juvenile Polyposis Syndrome

The diagnostic criteria for juvenile polyposis syndrome (JPS) include: the cumulative development of 5 or more colonic juvenile polyps; the presence of juvenile polyps in the stomach or small intestine (excluding other polyposis syndromes); or the presence of any juvenile polyp with a positive family history of JPS.3,4...

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