Does Differentiated Squamous Intraepithelial Neoplasia Occur in the Cervix?

Invasive cervical cell squamous carcinoma (ICC) classically develops from high grade cervical intraepithelial neoplasia of usual type (uCIN). Differentiated cervical intraepithelial neoplasia (dCIN) analogue to differentiated vulvar intraepithelial neoplasia has not been described in the cervix.

A pilot case of ICC developing from dCIN with atypia limited to the basal/parabasal layers, focally associated with neoplastic spread above the parabasal layer (usual-like CIN pattern or u-like CIN) was identified. The previous cervical biopsy was under-diagnosed as low grade CIN. A total of 33 consecutive cases of ICC were reviewed to identify dCIN, u-like CIN and uCIN.

The ICC developed from dCIN/u-like CIN in 2 patients, 46 and 47-year-old (group 1), mixed dCIN/u-like CIN and uCIN in 7 patients, 36±3-year-old (group 2) and from uCIN in 24 patients, 47±9-year-old (group 3). In group 1, focal uCIN but not connected to ICC was also seen and Pap smears showed only hyper-keratinized cells with mildly atypical nuclei. Endocervical gland involvement by CIN was absent in group 1, focal in group 2 and extensive in group 3. All cases showed diffuse p16 staining. P53 reactivity was noted in basal/parabasal in dCIN, predominantly lower and upper parts of the epithelium in groups 2 and 3, respectively.

Totally, 27% of ICC cases had associated dCIN/u-like CIN and in younger patients than in the uCIN group. Larger studies are needed to confirm dCIN/u-like CIN as significant precursor lesions of ICC.