Thin HSIL of the Cervix: detecting a variant of high-grade squamous intraepithelial lesions with a p16INK4a-antibody

Aims: The WHO defines thin HSIL as a high-grade intraepithelial lesion of the cervix that is usually less than 10 cells thick. These lesions usually develop in early metaplastic squamous epithelium without anteceding LSIL. The prevalence of thin HSIL is not well documented. We evaluated different characteristics of thin HSIL at time of treatment. Methods and results: We studied 25 formalin-fixed and paraffin-embedded conization specimens processed as step-serial sections. HSIL < 9 cells thick were classified as thin HSIL. HSIL > 10 cells thick were classified as classic HSIL. Immunohistochemical p16ink4a stainin…