Epithelial dysplasia
Epithelial dysplasia, a term becoming increasingly referred to as intraepithelial neoplasia, is the sum of various disturbances of epithelial proliferation and differentiation as seen microscopically. Individual cellular features of dysplasia are called epithelial atypia. Examples of epithelial dysplasia include cervical intraepithelial neoplasia – a disorder commonly detected by an abnormal pap smear) consisting of an increased population of immature (basal-like) cells which are restricted to the mucosal surface, and have not invaded through the basement membrane to the deeper soft tissues. Analogous conditions include vaginal intraepithelial neoplasia and vulvar intraepithelial neoplasia. Metanephric dysplastic hematoma of the sacral region  is a dysplastic overgrowth observed in infants. Screening. Some tests which detect cancer could be called "screening for epithelial dysplasia". The principle behind these tests is that physicians expect dysplasia to occur at the same rate in a typical individual as it would in many other people. Because of this, researchers design screening recommendations which assume that if a physician can find no dysplasia at certain time, then doing testing before waiting until new dysplasia could potentially develop would be a waste of medical resources for the patient and the healthcare provider because the chances of detecting anything is extremely  low. Some examples of this in practice are that if a patient whose endoscopy did not detect dysplasia on biopsy during screening for Barrett's esophagus, then research shows that there is little chance of any test detecting dysplasia for that patient within three years. Individuals at average-risk for colorectal cancer should have another screening after ten years if they get a normal result and after five years if they have only one or two adenomatous polyps removed. Microscopic changes. Dysplasia is characterised by four major pathological microscopic changes: Other changes that occur in epithelial dysplasia include: Epithelial cell  dysplasia is divided into three categories of severity: mild, moderate, and severe. Epithelial dysplasia becomes microinvasive squamous cell carcinoma once the tumor begins to invade nearby tissue. Dysplasia vs. carcinoma "in situ" vs. invasive carcinoma. These terms are related since they represent three stages in the progression of many malignant tumors of the epithelium. The likelihood of the development to cancer is related to the degree of dysplasia.