[The p16INK4a protein: a cytological marker for detecting high grade intraepithelial neoplasia of the uterine cervix].

The identification of a small percentage of high grade cervical intraepithelial neoplasia (HGCIN) among patients with a diagnosis of atypical squamous cells of undetermined significance (ASC-US) and low grade squamous intraepithelial lesion (LSIL) is one of the difficulties in cytology based cervical cancer screening. p16INK4a is a surrogate marker for the initiation of HPV mediated cervical carcinogenesis. This article describes the detection of the protein p16INK4a by immunocytochemistry coupled with the use of a nuclear score to differentiate abnormal basal cells from metaplastic or atrophic cells. The results of a pilot series of 210 liquid based cytology (LBC) specimens of which 108 were considered normal, 52 with a diagnosis of LSIL and 50 with a diagnosis of high grade SIL are described. The second series includes 137 LBC specimens with an ASC-US diagnosis and 88 with a LSIL diagnosis with an histological correlation. The overall sensitivity for the diagnosis of HGCIN using for the labeled squamous cells a nuclear score superior to 2 was 96% and the specificity was 83%. The sensitivity in the ASC-US was 95% and the specificity was 84%, in the LSIL group 100% and 81%, respectively. These data suggest to study a large series of LBC smears with a diagnosis of ASC-US and LSIL to confirm its efficacy of predicting the presence of an HGCIN.