[Critical study of digestive tract dysplasia]

Dysplasia designate the presence in a tissue of atypical architectural and cytological features similar to those observed in carcinogenesis. It must be clearly distinguished from metaplasia which is, in itself, a benign state characterized by the progressive replacement of a normal tissue by an other, normally foreign to this organ. Although the theoretical definition of dysplasia and its relation to carcinogenesis is well demonstrated, numerous difficulties remain regarding its classification and clinical applications. Recent research based on follow-up studies and on diagnostic reproducibility have somewhat clarified the problem, leading to a simplification of the classification in two tiers (high and low grade). High grade dysplasia can be considered as a high cancer risk necessitating a follow-up at short intervals and possibly requiring surgery. Low grade dysplasia, which can regress or progress very slowly represents a low cancer risk. After a first control at one or two months, it is suggested that endoscopic follow-up can be proposed at larger intervals (one or two years). The authors study the aspects of the dysplasia at the different levels of the gastrointestinal tract and summarise the clinical implication of this diagnosis.