Characteristics of malignant phenotypes in familial polyposis.

Numerous clinical syndromes associated with multiple polypoid lesions of the gastrointestinal tract have been described. These syndromes generally have two striking characteristics: 1) Most of them are familial with the disease being inherited as a mendelian autosomal dominant trait, and 2) most of the affected patients have moderate to marked propensity to develop gastrointestinal carcinoma, usually of the large bowel. Whereas previously many of these syndromes were thought to be well-defined entities, it now appears that there is overlap between certain of them such that they appear more similar than different. The clinical and pathologic characteristics of the various gastrointestinal polyposis syndromes and the methods of diagnosis and treatment are reviewed in this manuscript.