The cells look abnormal under the microscope, but they do not invade nearby healthy tissue. There are three degrees of dysplasia, classified as mild, moderate, or severe, depending on how abnormal the cells appear under the microscope. The word squamous describes cells which are thin, flat, and lie on the outer surface of the cervix. The word lesion refers to abnormal tissue. An intraepithelial lesion means that the abnormal cells are present only in the surface layers of the cells.
Neoplasia means a new abnormal growth of cells.
Intraepithelial refers to the surface layers of the cells. Carcinoma in situ describes a pre-invasive cancer that involves only the surface cells and has not spread into deeper tissues. Cervical cancer, or invasive cervical cancer, occurs when abnormal cells spread deeper into the cervix or to other tissues or organs. Mild dysplasia may also be classified as low-grade SIL or CIN 1. Moderate dysplasia may also be classified as high-grade SIL or CIN 2.