Adjunct p16INK4a Immunohistochemistry Aids the Detection of High-Grade Squamous Intraepithelial Lesions in Endocervical Curettage Specimens

Objectives We questioned whether the use of p16(INK4a) immunohistochemistry in endocervical curettage (ECC) specimens would improve the detection of high-grade squamous intraepithelial lesions (HSIL) in a high-risk patient population. Methods Papanicolaou test results were retrieved in 58 consecutive ECC specimens that were previously diagnosed as no histopathologic abnormality in patients with antecedent HSIL or atypical squamous cells, cannot exclude HSIL. An H&E recut and immunohistochemistry for p16(INK4a) were performed on all cases. Results HSIL were found in 18 (31%) ECC specimens originally interpreted as negative. Of these 18 cases, three had moderate-sized fragments of ectocervical epithelium with HSIL seen on the recut H&E with concurrent positivity for p16(INK4a). Fourteen cases had rare to occasional clusters of atypical cells with strong immunoreactivity for p16(INK4a). A single case showed a medium-sized fragment of HSIL on the p16(INK4a)-stained section. Conclusions The use of recuts and adjunct p16(INK4a) should be considered when evaluating ECC specimens in high-risk patient populations.