Utility of p16 (INK4a) Immunostaining in Cervical Biopsies

Recognition of cervical dysplasia or human papilloma virus (HPV) effect can be a very difficult task, particularly in those cases with "borderline" morphologic features. Interpretation in such cases is highly subjective, and it is not surprising that interobserver reproducibility of HPV effect and mild squamous dysplasia is poor. Because the clinical (and social) implications of these diagnoses can be significant, ancillary methods that can assist in accurate diagnosis of these conditions have been sought by a number of investigators. This month, we review the utility of immunostaining for p16 (INK4a) for this purpose, a regulatory protein that decelerates the cell cycle.