A broad-based approach to differentiate CIN from its mimics: The utility of in situ hybridization and immunohistochemistry

Abstract

The hematoxylin and eosin slides of 100 consecutive cases diagnosed as CIN 1–2 were combined with 25 CIN 1 and 25 negative for CIN as documented by in situ HPV testing. The 150 cases were then reviewed blinded and scored as “CIN” or “negative for CIN”. Each of the 50 controls was correctly scored. Of the 100 cases, 62 were diagnosed as CIN and the other 38 were scored as negative for CIN on re-review. Each of the CIN cases was positive for HPV as proven by the in situ detection of either HPV DNA or the L1 capsid protein. The 38 cases diagnosed as negative for CIN and 38 of the CIN cases were tested for HPV DNA by in situ hybridization and for a panel of biomarkers that included p16, Ki67, importin-β, exportin-5, and Mcl1 plus the L1 HPV capsid protein. Each of the 38 CIN cases was positive for HPV as well as each biomarker that localized towards the basal aspect of the lesion. Two of the 38 negative for CIN cases were positive for HPV DNA/L1 capsid protein and each of the biomarkers. The other 36 cases were negative for HPV DNA/L1 protein and each of the biomarkers showed baseline expression. Thus, 36% of the diagnoses of CIN 1–2 were incorrect and this could have been prevented with either in situ detection of the viral DNA/capsid protein or the immunohistochemistry detection of a panel of biomarkers that included p16, Ki67, importin-β, exportin-5, and Mcl1.