Familial juvenile adenomatous polyposis.

Most colonic polyps in children are of the juvenile type and occur either as single or scattered colonic polyps. The peak incidence occurs between 4 and 6 yr of age, with a spontaneous decline from 12 to 15 yr. Significant clinical symptoms are rare, and operative therapy is rarely indicated. Diffuse colonic juvenile polyposis, however, varies with different clinical, prognostic, and genetic implications. In infancy, colonic polyposis may be associated with diffuse gastrointestinal involvement leading to fatal complications unless treated aggressively. In childhood, colonic polyposis can occur with a genetic variance with an increased incidence of familial intestinal malignancies. Colonic polyposis in childhood, both familial and nonfamilial, can present with a mixed form of juvenile and adenomatous polyposis. In children with colonic polyposis, the biopsy of a single polyp that reveals the histologic appearance of a juvenile polyp does not rule out the simultaneous existence of adenomatous polyps.