Last reviewed 10/2020

Cervical squamous epithelial dysplasia is characterised by:

  • basal hyperplasia - multi-layering of basal cells
  • nuclear pleomorphism
  • increased mitotic activity

Three grades are described:

  • CIN 1 - dysplasia limited to the basal one third of the squamous epithelium; previously referred to as "mild dysplasia"

  • CIN 2 - dysplasia extends into the middle third of the epithelium; previously, "moderate dysplasia"

  • CIN 3 - dysplasia extends into the upper third of the epithelium; previously, "severe dysplasia". The cells are virtually indistinguishable from frankly invasive carcinoma but the basement membrane remains intact