Diagnostic utility of p16 immunocytochemistry in metastatic cervical lymph nodes in head and neck cancers

Abstract

Background Human papilloma virus (HPV) testing can be useful in work‐up of patients presenting with cervical node metastasis, suspected to be of head and neck origin as HPV positive tumors show better response to therapy. The current study was planned to detect HPV in aspirates from metastatic cervical nodes using p16 immunocytochemistry in head and neck squamous cell carcinoma (HNSCC). Further correlation of HPV status between node metastasis and primary tumor was done. Methods The prospective study included 50 patients diagnosed as metastatic SCC in cervical nodes on fine needle aspiration with either known head and neck primary or primary detected post cytodiagnosis. Immunostaining for p16 was carried out on both smears and tissue sections. Results Forty‐three patients were male and seven were female. Age of the patients ranged from 35 to 80 years. Primary sites of HNSCC were oropharynx (25), oral cavity (14), and larynx (11). Immunocytochemistry for p16 on smears showed positivity in 28 cases. Immunohistochemistry for p16 in primary tumors was positive in 34. There was substantial agreement between p16 immunocytochemistry and immunohistochemistry (Kappa value: 0.823). The sensitivity of p16 immunocytochemistry for the detection of HPV in metastatic HNSCC was 82.4% while the specificity was 100%. The positive and negative predictive values were 100% and 72.7%, respectively. Conclusions P16 immunocytochemistry in HNSCC metastatic to cervical node mirrors the HPV status of the corresponding primary tumor. Hence in tumors of unknown origin presenting as cervical node metastasis, p16 immunocytochemistry can be employed for localization of the primary.

Validation of p16 immunocytochemical staining on alcohol‐fixed aspirate smears: A single‐institutional study with review of the literature

“…11 Reports of various testing options on FNA samples have included p16 IHC, DNA ISH, the Cobas HPV test, the Cervista HR-HPV and Cervista HPV16/HPV18 assays, and the Hybrid Capture 2 assay. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][29][30][31][32] With regard to performing p16 ICC on Cancer Cytopathology May 2022 cytology samples, the CAP guidelines recommend individual laboratories validate the appropriate cutoff for a positive result. This allows laboratories the flexibility to use their preferred cytology sample on which to perform p16 staining.…”

“…25,26 The study by Kapoor et al used a 50% ICC staining cutoff and found that sensitivity and specificity for the detection of HPV in cervical lymph node metastasis in head and neck SCC were 82.4% and 100%, respectively. 26 Yang et al performed p16 ICC on 50 neck-mass FNAs diagnosed as SCC compared with corresponding surgical tissue and used receiver operator curve analysis, which demonstrated that the best cutoff was 50% staining on smears with 74% sensitivity and 100% specificity. 25 In our study, we used FFPE surgical tissue for comparison p16 IHC staining and found an overall concordance rate of 87.5%.…”

“…For head and neck FNA samples, the CAP guidelines recommend that HR‐HPV testing be performed in the appropriate clinical setting; however, they do not specify the type of testing methodology to be used because, currently, there is insufficient evidence to support such a recommendation 11 . Reports of various testing options on FNA samples have included p16 IHC, DNA ISH, the Cobas HPV test, the Cervista HR‐HPV and Cervista HPV16/HPV18 assays, and the Hybrid Capture 2 assay 13‐26,29‐32 . With regard to performing p16 ICC on cytology samples, the CAP guidelines recommend individual laboratories validate the appropriate cutoff for a positive result.…”

“…More recent studies of p16 ICC on aspirate smears with associated tissue samples for comparison staining showed promising results 25,26 . The study by Kapoor et al used a 50% ICC staining cutoff and found that sensitivity and specificity for the detection of HPV in cervical lymph node metastasis in head and neck SCC were 82.4% and 100%, respectively 26 . Yang et al performed p16 ICC on 50 neck‐mass FNAs diagnosed as SCC compared with corresponding surgical tissue and used receiver operator curve analysis, which demonstrated that the best cutoff was 50% staining on smears with 74% sensitivity and 100% specificity 25 …”

“…Furthermore, in addition to the inherent cellular variability seen in cell blocks of various cases in practice, the quality of cell blocks may also be influenced by the type of collection media used and its impact on the percentage of cells staining positive. 21,22 Studies using FNA smears have been reported but are fewer in number, [23][24][25][26] with some limited by lack of associated control tissue or interpretation based solely on cytoplasmic staining. 23,24 Determining the HPV status in oropharyngeal tumors can have a significant impact on treatment and clinical outcomes.…”