Abnormal cells on the surface of the cervix, classified as either mild (70% of cases fall into this category; the cells regress on their own), moderate, or severe, or as class 1, 2 or 3. While dysplasia itself does not cause health problems, it is considered to be a precancerous condition. Left untreated, dysplasia sometimes progresses to an early form of cancer known as cervical carcinoma in situ, and eventually to invasive cervical cancer.