The most common gastrointestinal tumor in children is the benign single juvenile polyp. 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, 1 or more adenomas, polyps of multiple histologic types, or abnormal dysplastic histology suggest a hereditary or genetic cancer predisposition syndrome that can include cancers of multiple organ systems. A family history of colon cancer under the age of 50 years and/or gastrointestinal polyps affecting multiple relatives over several generations warrants evaluation for the presence of a hereditary cancer syndrome.
The presenting features of hereditary colorectal cancer/polyposis syndromes can be highly variable within a given family. Most of these syndromes are autosomal dominant, with syndrome features being seen in other family members. The age of symptom presentation, polyp number, and cancer development can differ among affected family members who carry the same gene mutation. New spontaneous or de novo germline mutations can be seen in up to one-third of newly diagnosed pediatric polyposis patients.
Adenomas, as precancerous lesions, are either sessile or pedunculated and can be difficult to differentiate from hamartomas by endoscopic appearance. Adenomas are by definition dysplastic, having disorganized epithelial proliferation and loss of goblet cells, and display cellular and nuclear atypia. Dysplasia can progress from mild to severe with loss of cell growth regulation and can indicate the progression from adenoma to early carcinoma. Polyps can have mixed histologic features of both hamartomas and adenomas. Finding an adenomatous polyp in a child or adolescent can suggest the diagnosis of a hereditary polyposis syndrome, which can be associated with an increased risk of colon or other cancers. Further evaluation and surveillance are indicated.
Typical juvenile polyps can be seen in up to 2% of children under the age of 10 years. These lesions can present with painless rectal bleeding during defecation or can be identified visually as they prolapse through the anus. On occasion, colonic juvenile polyps can 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; however, up to half of children with juvenile polyps have more than 1 polyp, with the majority being in the left 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.
HEREDITARY HAMARTOMATOUS POLYPOSIS SYNDROMES
Juvenile Polyposis Syndrome