Does p16 Immunostain Discriminate between Low-Risk and High-Risk Human Papilloma Virus Infection?
Thad M Primeaux, Jaiyeola Thomas. LSUHSC-Shreveport, LA
Background: p16, a cyclin-dependent kinase inhibitor and G1/S-phase cell cycle checkpoint regulator is often used as a marker of HPV and is an E7-mediated functional inactivator of retinoblastoma protein (pRB). The loss of pRB function leads to over-expression of p16 protein due to lack of negative feedback. E7 protein from HR-HPV is considered more effective in the inactivation of pRB compared to that of LR-HPV, hence the use of p16 as a surrogate marker of HR-HPV. This study aims to assess the efficacy of p16 staining to discriminate between HR-HPV and LR-HPV.
Design: 47 consecutive tissue biopies with HPV-ISH studies done within the last year were reviewed. All had 5-μm sections cut and stained with p16 antibody. p16 staining intensity and patterns were scored semi-quantitatively and correlated with the HPV-ISH results.
Results: Table 1 shows the HPV-ISH status and p16 staining correlation with tumor types. The LR-HPV HNSCC case was also HR-HPV+. Two laryngeal papillomas (LP), in addition to positive staining for LR-HPV, had focal HR-HPV positivity. The LP showed weak basal layer, membranous and scattered isolated p16+ epithelial cells, which was distinct from the full-thickness, intense, diffuse cytoplasmic and nuclear staining in HR-HPV+ tumors (Figures 1&2).
|Diagnosis||# of cases||LR-HPV DNA||HR-HPV DNA||p16||Incomplete Data|
|Laryngeal papilloma||6||4||2 (focal)||4 (focal)||0|