HPV testing through p16 immunocytochemistry in neck‐mass FNA and its correlation with tissue samples

Abstract

Background Fine‐needle aspiration (FNA) of a neck mass is frequently the initial diagnostic procedure for patients with human papillomavirus–positive head and neck squamous cell carcinoma. By performing a p16 immunocytochemistry (ICC) stain on FNA material, the pathologist can help to direct the treating physician's search for the primary site and to select the proper management for the patient. There is currently no established threshold for the evaluation of p16 ICC in cytology samples. This study was aimed at establishing an optimal threshold for p16 ICC interpretation in cytology samples. Methods The pathology databases were searched for all neck‐mass FNAs diagnosed as squamous cell carcinoma from January 2010 to March 2019. p16 ICC was performed on cytology smears, and the percentage and intensity of p16‐positive cells were assessed. Receiver operating characteristic (ROC) curves were plotted to determine the best cutoff threshold for p16 positivity on cytology smears. Results p16 ICC was performed on 50 cytology smears. An analysis of 8 different thresholds (combinations of the percentage and intensity of the p16 stain) using ROC curves demonstrated the best threshold to be 50% p16 staining with a sensitivity of 74% and a specificity of 100%. Applying the threshold used for surgical specimens (70%) to cytology samples resulted in a low sensitivity (45%). Conclusions p16 ICC on cytology smears shows diminished staining in comparison with surgical samples. Using 50% staining as the cutoff to consider positivity for p16 in cytology smears is proposed to decrease false‐negative results while maintaining specificity.

Correlation of p16 immunostaining in cell‐blocks with corresponding tissue specimens for squamous cell carcinomas of the oropharynx

“…12,14 In contrast, several studies have investigated a p16 cut-off of ≥1%, and, when compared to staining in tissue specimens or HPV ISH results, have shown improved sensitivity levels ranging from 66.7% to 100%. 12,14,[16][17][18] A few studies have used a more intermediate threshold, ranging from 10%-15% 12,19,20 to 50%, 21 suggesting that these cut-offs are more practical and allow for improved testing metrics. 12 We argued in a previous study and a recent literature review that the optimal cut-off may be in the range of 5%-15%.…”

Quantitative assessment of p16 expression in FNA specimens from head and neck squamous cell carcinoma and correlation with HPV status

“…Number of clusters, largest cluster size, and number of tumor cells were assessed quantitatively. Both nuclear and cytoplasmic staining in viable tumor cells were scored for intensity and extent: The percentage of p16‐positive tumor cells was recorded in 5% increments and intensity of staining reported as follows: negative (absence of staining), weak (faint staining), moderate (darker staining), and strong (dense staining) 22,23 . Scoring was assessed independently by 2 cytopathologists (R.A‐R.…”

Molecular Diagnostics in Human Papillomavirus-Related Head and Neck Squamous Cell Carcinoma

“…Several studies suggest that the cut-off of 70% for FNAB samples is too high, generating many false-negative results. To address this question, a recent study was undertaken to determine optimal test characteristics for p16 immunocytochemistry (ICC), utilizing p16 status on corresponding surgical samples as the gold standard [36]. Using receiver-operating characteristic curves in their results, the authors propose using a 50% threshold for p16 ICC on FNAB samples, which was associated with a sensitivity of 74% and specificity of 100%, compared to the 70% threshold with a sensitivity of 45% and specificity of 100%.…”