Premalignant and early malignant lesions in the gastrointestinal tract: definitions, terminology, and problems.

The definition of a "premalignant" lesion is discussed, together with its relationship to dysplastic change. The definition and description of dysplasia are given. Systems for grading dysplasia are set out, and the clinical implications of these changes are discussed. Although the "dysplasia terminology" in current use remains the gold standard for clinical practice, a series of more recent developments, including the discovery of flat and depressed adenomas, the possibility of de novo carcinoma throughout the gastrointestinal tract, as well as advances in molecular biology, raise the question of whether this terminology will be adequate in future. Other terminologies exist that provide an alternative viewpoint, but none is satisfactory.