CERVICAL INTRAEPITHELIAL NEOPLASIA (CIN):
Mild Dysplasia / CIN 1: Dysplasia confined to the lowest third of the epithelium.
Moderate Dysplasia / CIN 2: Dysplasia involving the lower two thirds of the epithelium.
Severe Dysplasia / CIN 3: Dysplasia extending into the upper third of the epithelium, but not involving the full thickness.
Carcinoma In Situ / CIN 3: A squamous intraepithelial lesion in which nuclear abnormalities involve the full thickness of the epithelium.
Scully et al, WHO; Histological Typing of Female Genital Tract Tumors, 2nd ed,1994