p16 immunohistochemistry is recommended by the CAP-ASCCP Lower Anogenital Squamous Terminology (LAST) Standardization Project for human papillomavirus associated Lesions as an adjunct to morphologic assessment in the diagnosis of high-grade squamous intraepithelial lesion.
However, for reasons of considerable inter-observer variation in CIN grade assignment and for want of a biomarker validating a three-fold stratification, CAP-ASCCP LAST consensus guidelines recommend a two-tier system: low- or high-grade squamous intraepithelial lesions (LSIL or HSIL).