Juvenile polyposis of the colon with atypical adenomatous changes and carcinoma in situ. Report of a case and review of the literature.

Juvenile polyps are thought to have no malignant potential; however, we report a case of diffuse juvenile polyposis coli in a 19-year-old man where mucosal dysplastic changes ranging from mild dysplasia to carcinoma in situ are present. The pathogenetic development of these polyps and their malignant potential are discussed.