mild dysplasia, called CIN I or flat condyloma. This lesion is characterized by koilocytotic changes mostly in the superficial layers of the epithelium- nuclear hyperchromasia and angulation with perinuclear vacuolization produced by cytopathic effect of HPV
In CIN II the dysplasia is more severe, with maturation of keratinocytes delayed into the middle third of the epithelium. It is associated with some variation in cell and nuclear size, heterogeneity of nuclear chromatin and mitoses above the basal layer, extending in to the middle third of the epithelium
CIN III, marked by even greater variation in cell and nuclear size, marked chromatin heterogeneity, disorderly orientation of the cells, and normal or abnormal mitoses; these changes affect virtually all layers of the epithelium and are characterized by loss of maturation. Differentiation of surface cells and koilocytotic changes have usually disappeared
carcinoma in situ.