Dysplasia of the gut: the diagnosis is harder than it seems.

Preneoplastic epithelia of the gut have been given several different names, but the one most often used is dysplasia. Dysplasias of the gut are diagnosed by pathologists, using a set of cytologic and architectural features, and are divided into two grades: low- and high-grade. Although the definitions imply that all low-grade dysplasias are similar (as are all high-grades), in reality, there is significant heterogeneity in the appearances of each grade of dysplasia. Thus, separating low-from high-grade epithelium may be difficult. In addition, the features that characterize low-grade epithelia are very similar to many examples of epithelial regeneration, and so these may not be readily separable. Such cases may be classified as being indefinite for dysplasia. For these reasons, and because the implications for patient care are significant, the interpretations of biopsies taken for dysplasia surveillance are considered challenging by most pathologists. Clinicians must understand the challenging nature of these biopsies, communicate with the pathologists who will interpret such biopsies, and obtain an adequate sample of the mucosa to ensure that dysplasia, if present, will be biopsied and appropriately diagnosed.