Atypical immature cervical metaplasia: immunoprofiling and longitudinal outcome

Atypical proliferations of immature cervical squamous metaplasia were reviewed and correlated with p16 and Ki-67 expression to determine whether immunoprofiling could enable more conventional classification. The longitudinal outcome of atypical immature metaplasia (AIM) and predictive role of biomarker expression were also investigated. All atypias of immature squamous metaplasia in the year 2000 were reviewed and stained with p16 and Ki-67. Biomarker features were evaluated and the Ki-67 index calculated. Diagnoses were correlated with the immunoprofile of each antibody, both separately and combined. The progression to squamous intraepithelial lesion (SIL) of lesions reclassified as AIM was determined, and biomarker immunoprofiles were correlated with outcome. The 172 atypias were reviewed as 3 (1.7%) negative, 54 (31.4%) benign, 60 (34.9%) AIM, 43 (25%) low-grade SIL (LSIL), and 12 (6.9%) high-grade SIL (HSIL). HSIL correlated significantly with a combined high index (>15%) and p16 diffusely positive profile (P = .01). Benign diagnoses correlated significantly with a low index (1%-15%) and p16 negative or focal profile (P = .01). AIM and LSIL correlations were not significant, but their profiles were very variable and nearly identical. AIM was the only pathology in 43 cases, and follow-up was available for 32 (74.4%). SIL developed in 66% (50% LSIL and 16% HSIL) and p16 positivity correlated (P = .02). p16 and Ki-67 immunoprofiling are reliable in reclassifying some atypical proliferations of immature squamous metaplasia as HSIL and some as benign. The similarity between AIM and LSIL in regard to their immunoprofile as well as outcome suggests AIM is a morphological type of LSIL.