The utility of p16 immunostaining in fine needle aspiration in p16-positive head and neck squamous cell carcinoma

A case of fine-needle aspiration of a neck mass with atypical squamous cells and macrophages

Head and neck lesions often undergo fine-needle aspiration to determine the appropriate management and therapeutic decisions. However, there are numerous diagnostic challenges encountered with these specimens, particularly, if atypical squamous cells are identified. Here, we present a case of an enlarging right neck mass in a 38-year-old female and discuss the diagnostic difficulties and potential pitfalls. Additionally, we review the approach to diagnosis, including differential diagnostic considerations as well as available ancillary testing.

Diagnostic Accuracy of Circulating Tumor HPV DNA Testing in Patients With a Lateral Neck Mass

Importance

The most frequent presenting symptom for patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is a lateral neck mass. Circulating tumor tissue-modified viral (TTMV)-HPV DNA is a unique biomarker produced by the fragmentation of HPV DNA during the degradation of HPV-associated tumors, and its detection and quantitation are currently being used as an adjunct to imaging in monitoring for disease recurrence and may have utility for diagnosis.

Objective

To measure the diagnostic characteristics of TTMV-HPV DNA compared with gold standard tissue biopsy for diagnosing HPV-OPSCC in patients presenting with an indeterminate lateral neck mass.

Design, Setting, and Participants

This prospective diagnostic test study enrolled patients 18 years or older who presented with a lateral neck mass to a large urban tertiary health care system from December 2021 to June 2023. Participants underwent standard-of-care testing to obtain a tissue diagnosis and a single TTMV-HPV DNA measurement.

Main Outcomes and Measures

The primary outcome of interest was sensitivity, while specificity, positive predictive value, and negative predictive value were secondary end points. A subset analysis was performed comparing test performance metrics between TTMV-HPV DNA testing and fine-needle aspiration.

Results

A total of 138 patients were included, of whom 80 (58.0%) were men, with median age of 57.5 years (IQR, 43.3-67.0 years). Of 138 patients, 87 (63.0%) had neck masses in level 2 and 47 (34.1%) had HPV-OPSCC. TTMV-HPV DNA testing exhibited a sensitivity of 95.7% (95% CI, 85.5%-99.5% [45 of 47 patients]), specificity of 97.8% (95% CI, 92.3%-99.7% [89 of 91 patients]), positive predictive value of 95.7% (95% CI, 85.5%-99.5% [45 of 47 patients]), and negative predictive value of 97.8% (95% CI, 92.3%-99.7% [89 of 91 patients]).

Conclusions and Relevance

In this diagnostic study of patients presenting with a lateral neck mass, circulating TTMV-HPV DNA demonstrated excellent diagnostic test characteristics for the detection of HPV-OPSCC. Such testing may have particular utility for patients in whom obtaining adequate tissue is problematic, as is often the case with cystic neck masses and unknown primary tumors.

Parotid squamous cell carcinoma metastases: Application of human papillomavirus-DNA test on liquid-based cytology to recognize oropharyngeal origin of the neoplasm

Malignancies of the parotid gland are relatively uncommon and in most cases are primary neoplasms; intraparotid metastases are rare. Oral and oropharyngeal squamous cell carcinoma (O- and OP-SCC) can potentially metastasize to the parotid gland or intraparotid lymph nodes. Fine-needle aspiration cytology (FNAC) serves as the initial diagnostic approach for this purpose. HPV status in FNAC specimens is relevant and can guide the diagnostic workup, indicating a potential oropharyngeal origin of the primary tumor. A small series of occult SCC metastases is presented below, in which HPV-DNA testing of FNAC specimens helped identify primary neoplasms located in the oropharynx. US-guided FNAC of parotid nodules was conducted by an experienced interventional cytopathologist in three cases. Each patient underwent assessment of direct smears, cell blocks, and liquid-based samples for HPV testing. The morphological and immunocytochemical features of SCC were documented, and real-time PCR was employed for the detection and genotyping of HPV. The role of HPV testing on FNAC specimens in pinpointing the primary neoplasms in the oropharynx is highlighted. Consequently, FNAC samples emerge as valuable diagnostic and prognostic tools in this context, providing essential insights for patient management.

Principles of Analytic Validation of Immunohistochemical Assays: Guideline Update

CONTEXT.—

In 2014, the College of American Pathologists developed an evidence-based guideline to address analytic validation of immunohistochemical assays. Fourteen recommendations were offered. Per the National Academy of Medicine standards for developing trustworthy guidelines, guidelines should be updated when new evidence suggests modifications.

OBJECTIVE.—

To assess evidence published since the release of the original guideline and develop updated evidence-based recommendations.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and update the original guideline recommendations using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS.—

Two strong recommendations, 1 conditional recommendation, and 12 good practice statements are offered in this updated guideline. They address analytic validation or verification of predictive and nonpredictive assays, and recommended revalidation procedures following changes in assay conditions.

CONCLUSIONS.—

While many of the original guideline statements remain similar, new recommendations address analytic validation of assays with distinct scoring systems, such as programmed death receptor-1 and analytic verification of US Food and Drug Administration approved/cleared assays; more specific guidance is offered for validating immunohistochemistry performed on cytology specimens.

Preoperative Circulating Tumor HPV DNA and Oropharyngeal Squamous Cell Disease

Importance

The utility of preoperative circulating tumor tissue-modified viral human papillomavirus DNA (TTMV-HPV DNA) levels in predicting human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (HPV+ OPSCC) disease burden is unknown.

Objective

To determine if preoperative circulating tumor HPV DNA (ctHPVDNA) is associated with disease burden in patients with HPV+ OPSCC who have undergone transoral robotic surgery (TORS).

Design, Setting, and Participants

This cross-sectional study comprised patients with HPV+ OPSCC who underwent primary TORS between September 2021 and April 2023 at one tertiary academic institution. Patients with treatment-naive HPV+ OPSCC (p16-positive) and preoperative ctHPVDNA levels were included, and those who underwent neck mass excision before ctHPVDNA collection were excluded.

Main Outcomes and Measures

The main outcome was the association of increasing preoperative ctHPVDNA levels with tumor size and lymph node involvement in surgical pathology. The secondary outcome was the association between preoperative ctHPVDNA levels and adverse pathology, which included lymphovascular invasion, perineural invasion, or extranodal extension.

Results

A total of 70 patients were included in the study (65 men [93%]; mean [SD] age, 61 [8] years). Baseline ctHPVDNA levels ranged from 0 fragments/milliliter of plasma (frag/mL) to 49 452 frag/mL (median [IQR], 272 [30-811] frag/mL). Overall, 58 patients (83%) had positive results for ctHPVDNA, 1 (1.4%) had indeterminate results, and 11 (15.6%) had negative results. The sensitivity of detectable ctHPVDNA for identifying patients with pathology-confirmed HPV+ OPSCC was 84%. Twenty-seven patients (39%) had pathologic tumor (pT) staging of pT0 or pT1, 34 (49%) had pT2 staging, and 9 patients (13%) had pT3 or pT4 staging. No clinically meaningful difference between detectable and undetectable preoperative ctHPVDNA cohorts was found for tumor size or adverse pathology. Although the median preoperative ctHPVDNA appeared to be higher in pT2 through pT4 stages and pN1 or pN2 stages, effect sizes were small (pT stage: η2, 0.002 [95% CI, -1.188 to 0.827]; pN stage: η2, 0.043 [95% CI, -0.188 to 2.600]). Median preoperative log(TTMV-HPV DNA) was higher in active smokers (8.79 [95% CI, 3.55-5.76]), compared with never smokers (5.92 [95% CI, -0.97 to 1.81]) and former smokers (4.99 [95% CI, 0.92-6.23]). Regression analysis did not show an association between tumor dimension or metastatic lymph node deposit size and preoperative log(TTMV-HPV DNA). After univariate analysis, no association was found between higher log(TTMV-HPV DNA) levels and adverse pathology.

Conclusions and Relevance

In this cross-sectional study, preoperative ctHPVDNA levels were not associated with disease burden in patients with HPV+ OPSCC who underwent TORS.

It is time to improve the diagnostic workup of oropharyngeal cancer with circulating tumor HPV DNA: Systematic review and meta-analysis

The possibility of detecting circulating tumor HPV DNA (ctHPVDNA) in plasma in patients with oropharyngeal cancer has been demonstrated in several reports. However, these data are from small cohorts and available tests for detection of ctHPVDNA are not fully validated. The aim is to evaluate sensitivity, specificity, and accuracy of ctHPVDNA by ddPCR to define its efficacy in the clinical setting for the diagnosis of HPV + OPSCC. A comprehensive search of three different databases: MEDLINE, Embase, and Cochrane Library databases. A total of 998 patients were evaluated from the 13 studies. OPSSC p16+ were 729, while controls p16- were 269. The meta-analytic study estimated the diagnostic performance of ctHPVDNA as follows: pooled sensitivity and specificity of 0.90 (95% CI: 0.82-0.94) and 0.94 (95% CI: 0.85-0.98), respectively; positive and negative likelihood ratios of 12.6 (95% CI: 4.9-32.1) and 0.05 (95% CI: 0.02-0.13), respectively. ddPCR for ctHPVDNA has good accuracy, sensitivity, and specificity for diagnosis of HPV + OPSCC. ctHPVDNA kinetic represents a great reliable opportunity to improve diagnostic and therapeutic management of cancer patients and could open new perspectives for understanding tumor biology.

Performance of Liquid Biopsy for Diagnosis and Surveillance of Human Papillomavirus-Associated Oropharyngeal Cancer

Importance

There is growing interest in the use of circulating plasma tumor human papillomavirus (HPV) DNA for diagnosis and surveillance of patients with HPV-associated oropharyngeal squamous cell carcinoma (OPSCC). Recent advances in the assays, combining the identification of circulating HPV tumor DNA and tumor DNA fragment analysis (tumor tissue-modified viral [TTMV]-HPV DNA), have been shown to be highly accurate. However, use of these newer techniques has been limited to small cohort studies and clinical trials.

Objective

To establish the clinical efficacy of plasma TTMV-HPV DNA testing in the diagnosis and surveillance of HPV-associated OPSCC in a contemporary clinical setting.

Design, Setting, and Participants

This retrospective observational cohort study included patients with OPSCC who underwent TTMV-HPV DNA testing between April 2020 and September 2022 during the course of routine clinical care. For the diagnosis cohort, patients with at least 1 TTMV-HPV DNA measurement prior to initiation of primary therapy were included. Patients were included in the surveillance cohort if they had at least 1 TTMV-HPV DNA test performed after completion of definitive or salvage therapy.

Main Outcomes and Measures

Per-test performance metrics, including sensitivity, specificity, positive predictive value, and negative predictive value, for TTMV-HPV DNA testing.

Results

Of 399 patients included in the analysis, 163 were in the diagnostic cohort (median [IQR] age, 63 [56-68.5] years; 142 [87.1%] male), and 290 were in the surveillance cohort (median [IQR] age, 63 [57-70] years; 237 [81.7%] male). Of the 163 patients in the diagnostic cohort, 152 (93.3%) had HPV-associated OPSCC while 11 (6.7%) had HPV-negative OPSCC. The TTMV-HPV DNA sensitivity in pretreatment diagnosis was 91.5% (95% CI, 85.8%-95.4% [139 of 152 tests]), and the specificity was 100% (95% CI, 71.5%-100% [11 of 11 tests]). In the surveillance cohort, 591 tests conducted in 290 patients were evaluated. A total of 23 patients had molecularly confirmed pathologic recurrences. The TTMV-HPV DNA test demonstrated sensitivity of 88.4% (95% CI, 74.9%-96.1% [38 of 43 tests]) and specificity of 100% (95% CI, 99.3%-100% [548 of 548 tests]) in detecting the recurrences. Positive predictive value was 100% (95% CI, 90.7%-100% [38 of 38 tests]), and negative predictive value was 99.1% (95% CI, 97.9%-99.7% [548 of 553 tests]). The median (range) lead time from positive TTMV-HPV DNA test to pathologic confirmation was 47 (0-507) days.

Conclusions and Relevance

This cohort study demonstrated that when evaluated in a clinical setting, the TTMV-HPV DNA assay demonstrated 100% specificity in both diagnosis and surveillance. However, the sensitivity was 91.5% for the diagnosis cohort and 88.4% for the surveillance cohort, signifying that nearly 1 in 10 negative tests among patients with HPV-associated OPSCC was a false negative. Additional research is required to validate the assay's performance and, if validated, then further research into the implementation of this assay into standard clinical practice guidelines will be required.

A simplified molecular method to detect high-risk HPV using the Aptima HPV assay on head and neck FNA smears

BACKGROUND

Fine-needle aspiration is used as a diagnostic tool in head and neck oropharyngeal squamous cell carcinoma and its metastases. Prognosis and treatment rely on the presence or absence of the human papilloma virus. The purpose of this study was to validate the performance of the Aptima HPV assay using Hema-Diff stained fine-needle aspiration smears in the diagnosis of human papilloma virus-related oropharyngeal squamous cell carcinoma using a simplified method to obtain tumor cells for testing.

METHODS

Patients with a diagnosis of squamous cell carcinoma and positive p16 immunohistochemical staining were identified. Aptima Specimen Transport Media was used to remove tumor cells from the Hema-Diff stained slides using a moistened swab. The selected cells were tested for high risk-human papilloma virus using the Aptima HPV assay and Aptima HPV 16 18/45 genotype assay. The results were compared with the p16 immunohistochemical staining of the related cell block and surgical specimens.

RESULTS

Twenty-one of the 21 (100%) p16-positive cases were found to be positive for high risk-human papilloma virus, whereas 20 of 21 (95%) negative cases were found to be negative for high risk-human papilloma virus using the Aptima HPV assay.

CONCLUSION

The Aptima HPV assay can be used to detect high-risk human papilloma virus in Hema-Diff stained fine-needle aspiration smears of oropharyngeal squamous cell carcinoma with a sensitivity of 100% and a specificity of 95%. This provides a valuable alternative to p16 immunohistochemical staining of cell block sections that often lack appropriate numbers of tumor cells.

Utility of high-risk HPV RNA chromogenic in situ hybridization in cytology smears and liquid-based preparations from metastatic head and neck squamous cell carcinoma

BACKGROUND

High-risk human papillomavirus (HR-HPV) status is critical for the diagnosis, prognosis, and treatment of patients with oropharyngeal squamous cell carcinoma (OPSCC). Patients often present with enlarged cervical nodes, and fine-needle aspiration cytology (FNAC) is frequently the initial diagnostic procedure. Although p16 is the most widely used surrogate marker, problems with interpretation can limit its utility in FNAC. HR-HPV RNA in situ hybridization (ISH) has emerged as a specific way to assess HPV status on cell block preparations of cervical nodes. The authors evaluated the utility of HR-HPV ISH in conventional smears and liquid-based cytology (LBC) preparations of metastatic head and neck squamous cell carcinoma (SCC).

METHODS

Thirty-one aspirates of proven, HPV-related SCC (confirmed by p16 and/or HR-HPV ISH in corresponding surgical specimens) were selected. Ten aspirates of HPV-negative SCC were also retrieved. HR-HPV ISH was performed on 27 smears and 14 LBC preparations. All results were scored as positive, equivocal, or negative.

RESULTS

Eighty-four percent of metastatic, HPV-related SCCs were positive for HR-HPV RNA ISH, with high number of signals (n = 19) and low number of signals (n = 7), whereas five HPV-related SCCs were equivocal. All metastatic, HPV-negative SCCs were negative for HR-HPV ISH.

CONCLUSIONS

HR-HPV ISH can be reliably performed on smears or LBC preparations, particularly when cell blocks are unavailable or paucicellular. Results were easy to interpret when high numbers of signals were present but were challenging in aspirates with low or rare number of signals. The current study suggests that HR-HPV ISH could be used as the initial testing modality for determining HPV status in FNAC specimens of metastatic SCC.

Circulating HPV DNA in HPV-associated cancers

Human papillomavirus (HPV) infections are the primary cause of almost all cervical cancers, anal cancers, and a variable proportion of other anogenital tumors, as well as head and neck cancers. Circulating HPV DNA (cHPV-DNA) is emerging as a biomarker with extensive potential in the management of HPV-driven malignancies. There has been a rapid advancement in the development of techniques for analyzing cHPV-DNA for the detection, characterization, and monitoring of HPV-associated cancers. As clinical evidence accumulates, it is becoming evident that cHPV-DNA can be used as a diagnostic tool. By conducting clinical trials assessing the clinical utility of cHPV-DNA, the full potential of cHPV-DNA for the screening, diagnosis, and treatment of HPV-related malignancies can be corroborated. In this review, we examine the current landscape of applications for cHPV-DNA liquid biopsies throughout the cancer care continuum, highlighting future opportunities for research and integration into clinical practice.

High-risk human papillomavirus testing in cytology aspiration samples from the head and neck part 1: a review of the literature on available testing options

Human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma is increasing in incidence and is often first diagnosed on a cytology fine needle aspiration (FNA) specimen of metastatic nodal disease of the neck. In the setting of oropharyngeal squamous cell carcinoma, HPV status defines the disease with HPV-associated tumors having better overall prognosis than those that are HPV negative. Furthermore, metastatic squamous cell carcinoma of the neck of unknown origin requires testing for HPV as a positive result suggests an oropharyngeal primary. As a result, HPV testing in aspirate samples is increasingly important for the proper diagnosis and treatment of patients with head and neck squamous cell carcinoma. Although HPV testing in cervicovaginal cytology specimens is common and well-established, testing in head and neck FNA samples remains challenging. p16 immunohistochemistry is an excellent surrogate marker for HPV in tumors of known or suspected oropharyngeal origin, but the criteria used in histologic specimens may not be appropriate in cytology samples. FNA samples are more frequently hypocellular, and cytology cell blocks have variable fixation and processing steps, limiting the utility of p16 immunohistochemistry. Other potential testing options have been reported in the literature including staining of aspirate smears and molecular testing of liquid-based samples. The American Society of Cytopathology Clinical Practice Committee recently surveyed the American Society of Cytopathology membership to determine the current state of HPV testing in aspirate samples, and this review article is designed to provide a summary of the current literature on various testing options in FNA samples.

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

BACKGROUND

Determining human papillomavirus (HPV) status in oropharyngeal squamous cell carcinoma can have a significant impact on treatment and clinical outcomes. Because fine-needle aspiration (FNA) is typically an initial diagnostic modality in a patient workup for primary or suspected metastatic disease, immunostaining for p16 on FNA material is a promising option to determine HPV tumor status, possibly avoiding biopsies or excisions. In this study, the authors investigated the possibility of using alcohol-fixed smears as a reliable alternative for reporting p16 status.

METHODS

Twenty HPV-associated tumors and 20 non-HPV-associated tumors were identified using the gold-standard histologic cutoff for positivity of ≥70% strong nuclear and cytoplasmic staining. Matched FNA specimens were identified for comparison staining, and a positive p16 result was rendered on a single aspirate smear using the same cutoff of ≥70%.

RESULTS

On alcohol-fixed cytology smears, 16 of 20 (80%) HPV-associated tumors showed positive p16 staining in ≥70% tumor cells. Four cases showed lower level (30%-60%) nuclear and cytoplasmic staining. Nineteen of 20 (95%) non-HPV-associated tumors showed no or minimal p16 staining (0%-10%), and 1 case had a p16-equivocal cytology result.

CONCLUSIONS

The authors performed immunocytochemical validation for p16 using alcohol-fixed smears and observed promising results, offering this technique as a potential alternative to formalin-fixed tissue in the appropriate clinical context. By using a positive staining cutoff of ≥70%, this technique offers 80% sensitivity and 95% specificity for detecting HPV-associated tumors. Although it was not performed in the current study, HPV-specific testing on available formalin-fixed, paraffin-embedded tissue should be considered in cases with equivocal or negative p16 staining.

Relevance of gene mutations and methylation to the growth of pancreatic intraductal papillary mucinous neoplasms based on pyrosequencing

We aimed to assess some of the potential genetic pathways for cancer development from non-malignant intraductal papillary mucinous neoplasm (IPMN) by evaluating genetic mutations and methylation. In total, 46 dissected regions in 33 IPMN cases were analyzed and compared between malignant-potential and benign cases, or between malignant-potential and benign tissue dissected regions including low-grade IPMN dissected regions accompanied by malignant-potential regions. Several gene mutations, gene methylations, and proteins were assessed by pyrosequencing and immunohistochemical analysis. RASSF1A methylation was more frequent in malignant-potential dissected regions (p = 0.0329). LINE-1 methylation was inversely correlated with GNAS mutation (r =  - 0.3739, p = 0.0105). In cases with malignant-potential dissected regions, GNAS mutation was associated with less frequent perivascular invasion (p = 0.0128), perineural invasion (p = 0.0377), and lymph node metastasis (p = 0.0377) but significantly longer overall survival, compared to malignant-potential cases without GNAS mutation (p = 0.0419). The presence of concordant KRAS and GNAS mutations in the malignant-potential and benign dissected regions were more frequent among branch-duct IPMN cases than among the other types (p = 0.0319). Methylation of RASSF1A, CDKN2A, and LINE-1 and GNAS mutation may be relevant to cancer development, IPMN subtypes, and cancer prognosis.

Cell free HPV DNA provides an accurate and rapid diagnosis of HPV-associated head and neck cancer

PURPOSE

HPV-associated Head and Neck Squamous Cell Carcinoma(HPV+HNSCC) is the most common HPV-associated malignancy in the United States and continues to increase in incidence. Current diagnostic approaches for HPV+HNSCC rely on tissue biopsy followed by histomorphologic assessment and detection of HPV indirectly by p16 immunohistochemistry. Such approaches are invasive and have variable sensitivity.

EXPERIMENTAL DESIGN

We conducted a prospective observational study in 140 subjects (70 cases and 70 controls) to test the hypothesis that a non-invasive diagnostic approach for HPV+HNSCC would have improved diagnostic accuracy, lower cost, and shorter Diagnostic Interval compared to standard approaches. Blood was collected, processed for circulating tumor HPV DNA(ctHPVDNA) and analyzed with custom ddPCR assays for HPV genotypes 16,18, 33, 35 and 45. Diagnostic performance, cost and Diagnostic Interval were calculated for standard clinical work up and compared to a non-invasive approach using ctHPVDNA combined with cross-sectional imaging and physical exam findings.

RESULTS

Sensitivity and specificity of ctHPVDNA for detecting HPV+HNSCC was 98.4% and 98.6%. Sensitivity and specificity of a composite non-invasive diagnostic using ctHPVDNA and imaging/physical exam were 95.1% and 98.6%. Diagnostic accuracy of this non-invasive approach was significantly higher than standard of care (Youden index 0.937 vs 0.707, p=0.0006). Costs of non-invasive diagnostic were 36-38% less than standard clinical work up and the median Diagnostic Interval was 26 days less.

CONCLUSIONS

A non-invasive diagnostic approach for HPV+HNSCC demonstrated improved accuracy, reduced cost and a shorter time to diagnosis compared to standard clinical workup and could be a viable alternative in the future.

The utility of high-risk human papillomavirus in situ hybridization in cytology cell block material from cystic head and neck lesions

BACKGROUND

Human papillomavirus-related oropharyngeal squamous cell carcinoma (HPV-OPSCC) presents frequently as metastasis in a neck lymph node that may be cystic or necrotic. Fine-needle aspiration (FNA) biopsies are often first-line diagnostic procedures. p16 immunohistochemistry (IHC) is a surrogate marker for high-risk HPV (hrHPV) infection but can be challenging to interpret. This study evaluated the use of hrHPV in situ hybridization (ISH) in cytology cell blocks of cystic neck lesions.

METHODS

Twenty-four FNA cases with cell blocks and surgical correlates were evaluated. p16 IHC and hrHPV ISH were assessed on cell blocks (C-p16 and C-hrHPV ISH), and hrHPV ISH on surgical samples (S-hrHPV ISH). All results were classified as negative, positive, or equivocal.

RESULTS

Two cases were excluded because of insufficient tissue on recut. On the basis of C-hrHPV ISH cases, 12 were positive, 5 were negative, and 5 were equivocal. All 12 positive C-hrHPV ISH cases had concordant S-hrHPV ISH with no false positives. Of the 5 negative C-hrHPV ISH cases, 4 had concordant S-hrHPV ISH, and 1 had a discordant S-hrHPV ISH. Of the 5 equivocal C-hrHPV ISH cases, S-hrHPV ISH were both positive and negative. Fourteen cases were equivocal by C-p16; 9 cases were reliably classified by C-hrHPV ISH (5 positive, 4 negative; 64%).

CONCLUSIONS

C-hrHPV ISH can be reliably used, especially when positive. A negative or equivocal interpretation of C-hrHPV ISH may warrant repeat testing. Compared to C-p16, C-hrHPV ISH is more frequently diagnostic and could be helpful for HPV-OSCC diagnosis and management.

HPV-related head and neck cancers: Pathology and biology

Discovering the key role HPV plays in head and neck carcinogenesis has revolutionized our approach to cancers such as oropharyngeal carcinomas. As the role of HPV expands beyond the oropharynx, there is a pursued need to understand the oncogenic mechanisms of HPV-driven tumorigenesis and their implications. Optimizing HPV detection methods all while acknowledging their limitations will ensure our ability to diagnose HPV-driven neoplasia wherever clinically relevant.

p16 immunostaining in fine-needle aspirations of the head and neck: determining the optimal positivity threshold in HPV-related squamous cell cancer

INTRODUCTION

There is no consensus for interpretation of p16 immunohistochemistry (IHC) in cytology preparations. Our study aims to assess p16 IHC staining in formalin-fixed cytology cell blocks (CBs) from head and neck squamous cell carcinoma (HNSCC) fine-needle aspiration (FNA) specimens in comparison with surgical pathology p16 staining and to determine the reproducibility of p16 IHC scoring in CBs.

METHODS

A total of 40 FNAs from 2014 to 2019 of HNSCC with p16 IHC were obtained. CB p16 staining was scored independently by 5 cytopathologists as interval percentages of tumor cell positivity. Receiver operating characteristic (ROC) curves were examined to determine optimal cutoffs for each pathologist based on sensitivity and specificity values. Gwet's coefficient (AC₁) was calculated to assess inter-rater reliability.

RESULTS

Greater than 10% was the lowest threshold to reach 100% specificity with high sensitivity (55%-84%) in all 5 raters. Rater performances were similar, with areas under the curve (AUCs) ranging from 0.89 to 0.95. Using the >10% threshold, Gwet's AC₁ = 0.72 (95% CI: 0.56-0.89). Diagnostic performance improved further when low-cellularity cases were excluded, with AUC ranging from 0.94 to 0.99 and Gwet's AC₁ = 0.79 (95% CI: 0.61-0.98).

CONCLUSION

p16 IHC performed on cytology CBs can serve as a surrogate marker for the detection of HPV with high sensitivity and specificity levels. Using a threshold lower than that recommended for surgical pathology for the interpretation of p16 positivity may be appropriate for FNA cytology CB preparations. All cytopathologists in our study displayed reproducible high sensitivity and specificity values at the >10% threshold.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

ROC analysis of p16 expression in cell blocks of metastatic head and neck squamous cell carcinoma

BACKGROUND

Oropharyngeal squamous cell carcinoma is associated with human papillomavirus (HPV) and often presents with early metastasis to cervical neck lymph nodes that are amenable to fine-needle aspiration (FNA). The most common method of HPV status determination is p16 immunohistochemistry (IHC). The literature suggests that a lower threshold is needed for p16 positivity on cell block. We examined and quantified p16 IHC staining on cell block and used receiver operating characteristics (ROC) curve analysis to determine an optimal cutoff value with high sensitivity and specificity.

METHODS

Thirty-six FNAs of metastatic squamous cell carcinoma from cervical lymph nodes with p16 IHC were evaluated. The p16 stain was quantified in 5% increments and high-risk HPV mRNA in situ hybridization was performed as a gold standard test. Statistical analysis was performed.

RESULTS

Interobserver variability was evaluated and was shown to be low with an intraclass correlation coefficient of 0.857. ROC analysis was performed and showed that a cell block p16 IHC cutoff of 15% yielded the highest sensitivity (80%) and specificity (81.8%).

CONCLUSION

Our data show that a threshold of 15% p16 staining in cell block maximizes sensitivity and specificity.

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

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.

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

BACKGROUND

This study investigated p16 by immunohistochemistry (IHC) on cellblocks (CBs) and human papillomavirus (HPV) by polymerase chain reaction (PCR) in fine-needle aspiration (FNA) of head and neck squamous cell carcinoma (HNSCC).

METHODS

Receiver operating characteristic (ROC) curve analysis was used to assess test performance in CBs compared with p16 IHC in 42 surgical specimens from patients with HNSCC and in correlation with HPV by PCR in cytology specimens. The study assessed HPV by PCR in FNA specimens as a substitute for p16 IHC in surgical specimens.

RESULTS

Of 42 cases, 38 CBs showed malignant cells as cohesive clusters of viable cells with or without single tumor cells, whereas 4 specimens were composed exclusively of single tumor cells and degenerated cells. All p16-negative surgical specimens showed an absence of p16 staining in the corresponding CBs (n = 16). In the p16-positive surgical cases (n = 26), corresponding CBs with tumor clusters (n = 23) showed heterogeneous p16 expression ranging from 40% to 100%; however, scoring single cells was challenging and unreliable because of cellular degradation. ROC curve inspection showed the optimal threshold to be at least 40% p16 staining in tumor clusters with 100% sensitivity and specificity. In cases with inadequate CBs, HPV by PCR on needle rinse showed 88% sensitivity and 100% specificity for p16 expression in surgical specimens.

CONCLUSIONS

A cutoff of at least 40% p16 expression in tumor clusters may be appropriate for p16 positivity in cytology CB specimens. A positive HPV finding by PCR on needle rinse can be used as a substitute for p16 expression in surgical specimens.

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

OBJECTIVE

The goal of this study was to evaluate the performance of p16 staining in cell-blocks vs tissue specimens as a surrogate marker for human papillomavirus (HPV) status in oropharyngeal squamous cell carcinomas.

METHODS

Head and neck squamous cell carcinoma cases presenting as a neck mass with a p16 result on cytology and corresponding tissue specimens (1 January 2014 to 30 June 1920) were included in the study. The following were assessed from cell-block material: number of tumour clusters, percentage of tumour cells with p16 staining, and presence of staining in clusters vs single cells. Results were compared to tissue p16 status. Results of any other ancillary HPV testing were also noted.

RESULTS

Forty-two head and neck squamous cell carcinoma neck metastases (35 oropharyngeal, five non-oropharyngeal, and 2 unknown primaries) were identified. The p16 staining pattern in cell-blocks was seen in single cells (27.6%), clusters (44.8%), or both (27.6%). The percentage of tumour cells staining for p16 in cell-blocks was much lower than in corresponding tissue specimens. There were four false negatives and one false positive (concurrent HPV DNA polymerase chain reaction testing was positive in cytology and surgical material).

CONCLUSIONS

Compared to tissue, the cut-off for p16 interpretation in cell-blocks is substantially lower and staining may be present in single cells or clusters. In 96.9% of cases, any p16 staining in cell-blocks correlated with positive p16 staining in surgical specimens. However, a negative or discrepant p16 result on cell-block should prompt confirmatory HPV studies, as false negative p16 staining in cell-blocks is high.

Cytological interpretation of p16 immunohistochemistry in head and neck carcinomas: does the choice of fixative matter?

INTRODUCTION

Fine-needle aspiration (FNA) of nodal metastases plays a key role in the diagnosis of oropharyngeal squamous cell carcinoma (OPSCC). Because of significant clinical implications of human papillomavirus (HPV)-related OPSCC, immunohistochemistry for p16 as a surrogate marker for high-risk HPV is an important ancillary test. After our laboratory switched from CytoLyt to formalin fixative for FNA needle rinses generating cell block (CB) material, we investigated the impact of this protocol change on the accuracy of p16 results.

MATERIALS AND METHODS

FNA specimens of head and neck lesions with p16 staining performed on CB, from 1 year before and after the implementation of formalin-fixed CB (FCB) were identified. Nuclear and cytoplasmic p16 expression was scored and compared to p16 status on corresponding surgical specimens.

RESULTS

There were no false-positive results with either fixative. CytoLyt-fixed CB (CCB) had 47% (7 of 15) false-negative cases, whereas FCB had none, with 100% diagnostic accuracy for p16-negative (n = 6) and p16-positive (n = 15) results. False-negative CCB showed 0% to 10% nuclear and 0% to 65% weak cytoplasmic staining, whereas true-positive CCB showed 10% to 85% nuclear and 35% to 90% cytoplasmic staining. p16-negative FCB showed 0% nuclear and cytoplasmic staining, and p16-positive FCB showed 30% to 100% moderate-strong nuclear and cytoplasmic staining. Interobserver variability was greater with CCB.

CONCLUSIONS

In our laboratory, formalin fixation of CB material improved the accuracy of p16 interpretation. Staining in FCB was also more robust than CCB, which showed weaker cytoplasmic and more focal nuclear staining. Therefore, we advocate formalin fixation for head and neck cytology specimens that may require p16 testing.

The utility of high-risk human papillomavirus E6/E7 mRNA in situ hybridization in assessing HPV status on cell block

INTRODUCTION

Assessment of human papillomavirus (HPV) status is critical to the treatment and prognosis of patients with oropharyngeal squamous cell carcinoma. Patients often present with enlarged cervical lymph nodes which are amenable to fine needle aspiration (FNA) and cell block creation. The most widely used method for assessing HPV status is the surrogate marker p16. Other HPV specific methods such as high-risk HPV E6/E7 mRNA in situ hybridization (ISH) have been shown to perform as well as p16 and are easier to interpret. Our study evaluates the utility of high-risk HPV mRNA ISH in cell block specimens.

METHODS

Thirty-six cases of metastatic squamous cell carcinoma in cervical neck lymph node FNAs were identified over a 3-year period. All cases had p16 immunohistochemistry (IHC) performed on cell block. HR HPV mRNA ISH was performed on the cell block and compared to the p16 results. Additionally, p16 and HR HPV mRNA ISH status was assessed in those cases with corresponding surgical resections.

RESULTS

HR HPV mRNA ISH confirmed the p16 IHC (either positive or negative) in 24 of the 36 cases (66.7%). Six false negative cases were p16 negative/HR HPV mRNA ISH positive. HR HPV mRNA ISH was positive in 75% of the four p16 equivocal cases. Two cases were p16 positive/HR HPV mRNA ISH negative.

CONCLUSIONS

HR HPV mRNA ISH is no more difficult to perform in the IHC lab and is easier to interpret than p16 IHC. HR HPV mRNA ISH is a useful alternative to p16 in cell block specimens.

Liquid phase human papillomavirus genotype analysis of aspirated metastatic head and neck squamous cell carcinoma: Fine needle aspiration supernatant is a rich source of tumor DNA that can increase the diagnostic yield

BACKGROUND

Most patients with human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSC) present with lymph node metastasis. In these patients, fine needle aspiration (FNA) is not only a diagnostic tool, but a means for determining HPV status. HPV status, in turn, is used to determine tumor origin, prognosis, and even guide therapy. Thus, the limited sampling afforded by FNA must be optimized to meet heavy clinical demands.

PURPOSE

The purpose of this study was to determine whether the residual supernatant portion of the FNA could serve as a resource for reliable determination of HPV status DESIGN/METHOD: 25 FNAs from 24 patients with metastatic HNSC underwent HPV genotyping of post-centrifuged supernatant fluid from FNA needle rinses. HPV genotyping was performed using two real time PCR-based assays, the two-step LightCycler and the one-step automated cobas HPV tests. HPV status of the supernatant was compared with the paired FNA cell blocks and/or surgical tissue samples.

RESULTS

The supernatant was adequate for HPV testing in 24 (96%) of 25 cases. Of these, 14 (56%) were HPV positive and 11 (44%) negative by the LightCycler assay. HPV16 was the most commonly detected genotype (n = 12). When results of supernatant and paired cell block testing were compared, HPV status was concordant in all cases. The LightCycler method was more sensitive than the cobas assay due to its ability to detect an expanded profile of HPV variant genotypes.

CONCLUSION

The current standard of practice for patients with HNSC who undergo FNA is to construct a cell block and then discard the supernatant. This supernatant is a rich source of tumor DNA that can be used to detect HPV status. It should not be wasted.

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

The incidence of human papillomavirus (HPV)-related head and neck squamous cell carcinoma continues to increase. Accurate diagnosis of the HPV status of a tumor is vital, as HPV+ versus HPV- tumors represent two unique biological and clinical entities with different treatment strategies. High-risk HPV subtypes encode oncoproteins E6 and E7 that disrupt cellular senescence and ultimately drive tumorigenesis. Current methods for detection of HPV take advantage of this established oncogenic pathway and detect HPV at various biological stages. This review article provides an overview of the existing technologies employed for the detection of HPV and their current or potential future role in management and prognostication.

Threshold for interpretation of p16 immunostaining in fine-needle aspirate specimens of metastatic oropharyngeal squamous cell carcinoma

INTRODUCTION

Human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (HPV-OPSCC) has been recognized to have an excellent response to treatment and has a distinct pathologic staging. For this reason, HPV testing is recommended in cytology specimens of metastatic OPSCC, although the guidelines for testing are not clearly defined. The aim of the current study was to establish a threshold for interpretation of p16 in aspirates from metastatic OPSCC.

MATERIALS AND METHODS

Cases diagnosed as metastatic SCC by cytology in neck lymph nodes with concurrent p16 on cytology and on paired surgical specimen or an in situ hybridization (ISH) for HPV were included in the study. Stain intensity and percentage positive cells for p16 was compared with p16 on paired surgical pathology specimens and/or ISH RNA for HPV on cytology specimens.

RESULTS

Of the 52 cases diagnosed as metastatic SCC on neck aspirates, paired surgical pathology specimens and/or ISH HPV was available in 17 cases. A p16 expression in ≥10%-15% cells resulted in a sensitivity and negative predictive value of 66% and 37%, respectively. However, when even minimal expression in tumor fragments is considered positive, the negative predictive value increases to 100%.

CONCLUSIONS

We recommend that even minimal nuclear expression for p16 in viable tumor fragments must be considered as positive in cytology specimens. Expression limited to only background single tumor cells or in a necrotic specimen must be interpreted with caution.

Cytologic evaluation of p16 staining in head and neck squamous cell carcinoma in CytoLyt versus formalin-fixed material

BACKGROUND

The management of high-risk human papillomavirus (HR-HPV)-related oropharyngeal head and neck squamous cell carcinomas (HNSCCs) are distinct from HNSCC linked to smoking and alcohol use. HR-HPV-positive HNSCC frequently presents as a cervical lymph node metastasis. Because fine-needle aspiration (FNA) is often the initial diagnostic procedure, evaluating HR-HPV status in cytology specimens is important. The overexpression of p16 is a surrogate for HR-HPV; however, the evaluation of p16 in FNAs remains controversial.

METHODS

From September 2015 to December 2016, cytopathologists performed 25 FNAs of neck lymph nodes that were suspicious for HR-HPV-positive HNSCC. Initial passes produced smears for on-site evaluation and CytoLyt material. Additional passes were formalin-fixed. A CytoLyt cell block (CCB) and a formalin-fixed cell block (FFCB) were prepared, and p16 immunocytochemistry was performed.

RESULTS

In 24 of 25 cases, the FFCB had diffuse (≥70% of cells), strong nuclear/cytoplasmic p16 staining. In all 24 of these cases, HR-HPV was detected by in situ hybridization. The corresponding CCB had weak-to-moderate p16 staining in <70% of cells (range, 5%-60% of cells) in 17 cases, 4 had weak-to-moderate diffuse staining, and 4 were acellular. The percentage of p16-positive cells was significantly higher with FFCB than with CCB (formalin: 94% ± 2%; CytoLyt, 38% ± 7%; 2-tailed, paired Student t test; P < .001; Fisher exact test, P < .001).

CONCLUSIONS

The fixative used had a drastic impact on p16 staining, which explained the staining variability reported in the literature. FFCBs show a diffuse staining pattern, which correlates with HR-HPV status, whereas CCBs show a weaker and inconsistent staining pattern, which is more difficult to interpret.

Heterogeneity of p16 immunohistochemistry and increased sensitivity of RNA in situ hybridization in cytology specimens of HPV-related head and neck squamous cell carcinoma

BACKGROUND

Many patients with human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HPV-HNSCC) initially present with cervical lymph node metastases. Although p16 immunohistochemistry (IHC) is the most commonly used surrogate marker for HPV, however criteria in cytologic material are not well established. The objective of this study was to better characterize p16 IHC in cell blocks of metastatic HPV-HNSCC, and to evaluate the performance of HPV RNA in situ hybridization (RNA ISH).

METHODS

p16 IHC was performed on cell blocks from 97 metastatic HPV-HNSCC fine-needle aspiration specimens with HPV status confirmed by DNA or RNA ISH or polymerase chain reaction (PCR). Tumor cellularity (<100 cells, 100-500 cells, and >500 cells) and quality (presence of cell clusters, necrosis) were recorded. p16 staining intensity and extent (1%-9%, 10%-69%, and ≥70%) were scored. In addition, RNA ISH was performed on 38 PCR-positive cases.

RESULTS

p16 IHC was positive in 90 of 97 cases (93%), demonstrating variable patterns. p16 staining was found to be moderate to strong in 69 cases, with 37 cases (38%) demonstrating positivity in ≥70% of tumor cells. Weak staining occurred in 21 cases (22%) and 7 cases (7%) were negative. Of the 60 cases with weak and/or absent expression or staining in <70% of cells, 30 cases (50%) had <100 tumor cells, 12 (20%) lacked cell clusters, and 19 cases (32%) had extensive necrosis. RNA ISH was positive in 37 of 38 cases (97%) that were HPV positive by PCR.

CONCLUSIONS

p16 is heterogeneous in cell blocks of metastatic HPV-HNSCC, suggesting that any p16 positivity should prompt confirmatory HPV studies. RNA ISH appears to demonstrate high sensitivity, and laboratories even may consider using RNA ISH as a first-line HPV test in cytologic specimens.

Current Status of p16 Immunohistochemistry and HPV Testing in Fine Needle Aspiration Specimens of the Head and Neck

Human papilloma virus (HPV)-related squamous cell carcinoma (SCC) is biologically unique and has a better prognosis than conventional SCC of the head and neck. p16 immunohistochemistry emerged as a valuable surrogate marker for HPV in oropharyngeal SCC. The criteria for a positive p16 result in tissue specimens are well established. However, there is no consensus regarding interpreting p16 staining in cell blocks and other cytology specimens. This review discusses the current evidence on p16 testing in cytology specimens and also highlights other methods for HPV testing, including DNA and RNA in situ hybridization, as well as other molecular HPV tests.

A Comparison of E6H4 and G175-405 p16-specific Monoclonal Antibodies in Oropharyngeal Squamous Cell Carcinoma

The purpose of this investigation is to directly compare G175-405 and E6H4 p16-specific antibodies as immunomarkers of HPV-driven oropharyngeal carcinoma. The investigators designed a retrospective analysis using specimens from an archived tissue bank with known in situ hybridization and polymerase chain reaction status for HPV DNA. Fifty randomly selected oropharyngeal specimens were evaluated with both the G175-405 and E6H4 p16-specific monoclonal antibodies. Two pathologists, blinded to the HPV-specific testing status, evaluated p16 positivity for both antibody clones. Interrater agreement was determined using a Cohen κ coefficient. Sensitivity and specificity values were calculated using a standard 2×2 contingency table, then compared using McNemar test. Interrater agreement for interpretation of p16 expression was 92% (κ=0.84) for the G175-405 clone and 100% for the E6H4 clone (κ=1.0). The G175-405 stain had a sensitivity of 0.917 and specificity of 0.846. The E6H4 stain had a sensitivity of 1.000 and specificity of 0.769. Using McNemar test, there were no significant differences found for sensitivity (P=0.480) or specificity (P=0.480) values. The results of this study suggest that though both G175-405 and E6H4 antibody stains are statistically comparable immunomarkers for HPV-driven oropharyngeal carcinoma, the E6H4 clone offers improved interobserver reliability.

Cytopathologic characteristics of HPV-related small cell carcinoma of the oropharynx

BACKGROUND

Human papillomavirus (HPV)-related squamous cell carcinoma (SqCC) of the oropharynx is an epidemiologically and clinically distinct form of SqCC that is associated with an improved prognosis. However, HPV-related small cell carcinoma of the oropharynx is a rare and newly described variant that is associated with aggressive clinical behavior and poor outcomes. To date, fewer than 2 dozen reports of this entity exist in the literature, and there is no discussion of cytopathologic features. This article reports 6 cases and discusses the salient cytomorphologic findings, ancillary studies, and challenges when this entity is encountered.

METHODS

Anatomic pathology archives were searched to identify patients with a diagnosis of HPV-related small cell carcinoma of the oropharynx. Medical records were reviewed to document the following: age, sex, smoking status, other relevant clinical history, primary location, treatment, and clinical outcome. Both p16 and high-risk HPV in situ hybridization (ISH) studies were positive in at least 1 specimen from each patient. The pathologic diagnoses, cytomorphologic characteristics, immunocytochemical stains, and HPV ISH studies were reviewed and recorded for all available cases.

RESULTS

Six patients with 11 cytopathology specimens of HPV-related small cell carcinoma of the oropharynx were identified. The mean age was 61.3 years, and all patients died with widely metastatic disease (mean, 23 months; range, 12-48 months). Mixed small cell carcinoma and SqCC components were present in half of the cases.

CONCLUSIONS

The identification of a small cell component can be reliably performed with cytology preparations and is crucial because this (and not the HPV status) determines the prognosis.

New evidence-based guideline for HPV testing in head and neck cancers

It is now well established that a subset of head and neck carcinomas is defined by their association with high-risk types of human papillomavirus (HPV). These HPV-driven head and neck carcinomas are characterized by distinct histologic and clinical features, including an excellent prognosis and response to therapy. Although the recognition of this subtype of head and neck cancer has been a significant advancement in head and neck oncology, confusion has persisted regarding why, when, and how HPV testing should be carried out. The College of American Pathologists (CAP) recently published evidence-based guidelines addressing HPV testing in head and neck carcinomas, offering much-needed clarification on a complicated issue. This review will detail each CAP guideline while also explaining the rationale and methods for their creation.

Human Papillomavirus Testing in Head and Neck Carcinomas: Guideline From the College of American Pathologists

Context Human papillomavirus (HPV) is a major cause of oropharyngeal squamous cell carcinomas, and HPV (and/or surrogate marker p16) status has emerged as a prognostic marker that significantly impacts clinical management. There is no current consensus on when to test oropharyngeal squamous cell carcinomas for HPV/p16 or on which tests to choose. Objective To develop evidence-based recommendations for the testing, application, interpretation, and reporting of HPV and surrogate marker tests in head and neck carcinomas. Design The College of American Pathologists convened a panel of experts in head and neck and molecular pathology, as well as surgical, medical, and radiation oncology, to develop recommendations. A systematic review of the literature was conducted to address 6 key questions. Final recommendations were derived from strength of evidence, open comment period feedback, and expert panel consensus. Results The major recommendations include (1) testing newly diagnosed oropharyngeal squamous cell carcinoma patients for high-risk HPV, either from the primary tumor or from cervical nodal metastases, using p16 immunohistochemistry with a 70% nuclear and cytoplasmic staining cutoff, and (2) not routinely testing nonsquamous oropharyngeal carcinomas or nonoropharyngeal carcinomas for HPV. Pathologists are to report tumors as HPV positive or p16 positive. Guidelines are provided for testing cytologic samples and handling of locoregional and distant recurrence specimens. Conclusions Based on the systematic review and on expert panel consensus, high-risk HPV testing is recommended for all new oropharyngeal squamous cell carcinoma patients, but not routinely recommended for other head and neck carcinomas.

HPV-related Oropharyngeal Carcinoma: A Review of Clinical and Pathologic Features With Emphasis on Updates in Clinical and Pathologic Staging

There has been a sharp increase in the incidence of the human papilloma virus-related oropharyngeal squamous cell carcinoma, partly due to the increasingly widespread awareness and recognition of this entity. This review assimilates the recent histopathologic classifications, staging systems, rapidly expanding research base and developments in management of human papilloma virus-related oropharyngeal squamous cell carcinoma and summarizes their implications for routine diagnostic practice. Differential diagnoses and their cytologic appearances are detailed and the utility of p16 staining and other immunohistochemistry testing is discussed.

Immunohistochemical Detection of p16 in Clinical Samples

P16 immunohistochemical expression, a surrogate marker of the retinoblastoma pathway, has become a major adjunct in the routine practice mostly of cervical and head/neck pathology, but with other indications too. In this chapter, a detailed immunohistochemical technique for the detection of p16 is described, followed by indications and interpretation of its expression in uterine, ovarian, vulvar, penile, head-and-neck, melanocytic, and other pathologies.

Evaluation of Diagnostic Utility of a High-Risk Human Papillomavirus PCR Test on Formalin-Fixed, Paraffin-Embedded Head and Neck Tumor Tissues

The increasing prevalence of high-risk human papillomavirus (HR-HPV)-associated head and neck squamous cell carcinoma (HNSCC) has prompted strong clinical demands for detecting HR-HPV directly in the tumor. Although p16 immunohistochemistry (IHC) has been the standard testing method, it has limitations including false positivity, lack of sensitivity in low tumor cell samples such as fine-needle aspirate (FNA), and its subjectivity. We developed a modified method based on a commercial automated HR-HPV PCR assay and evaluated the performance characteristics and the diagnostic utility of this assay for direct HR-HPV detection in the HNSCC samples. HNSCC formalin-fixed, paraffin-embedded blocks were retrieved from archives including 44 excisions, 63 biopsies, and 16 FNAs. Tissue slices were trimmed from the blocks, deparaffinized, lysed, and loaded on the commercial automated platform for HR-HPV PCR. All specimens had a concurrent p16 IHC performed. The PCR assay showed high concordance with the p16 IHC (96%; 99/103) and excellent positive agreement (91.5%) and negative agreement (100%). In addition, the PCR assay provided more conclusive results in samples with equivocal p16 IHC results. The modified commercial automated HR-HPV PCR test is a labor-efficient, quick, reliable, sensitive, and specific method for detecting HR-HPV in formalin-fixed, paraffin-embedded samples. This assay also showed excellent diagnostic utility in samples with equivocal p16 IHC results, including FNA cell blocks.

Current and future techniques for human papilloma virus (HPV) testing in oropharyngeal squamous cell carcinoma

Despite a reduction in smoking and alcohol consumption, the incidence of oropharyngeal squamous cell carcinoma (OPSCC) is rising. This is attributed to human papilloma virus (HPV) infection and screening for HPV is now recommended in all cases of OPSCC. Despite a variety of clinically available tests and new non-invasive test strategies there is no consensus on which technique is best. This review reports on current techniques for HPV detection in OPSCC and the clinical applicability of emerging techniques. Literature searches of Medline, Embase and clinicaltrials.gov using the search terms 'head and neck neoplasms', 'squamous cell carcinoma' and 'HPV testing' were performed. 45 studies were identified and included. p16 immunohistochemistry (IHC), HPV DNA in situ hybridization (ISH) and HPV polymerase chain reaction (PCR) are the commonest tests to determine HPV status. p16 IHC and HPV DNA PCR are highly sensitive whilst HPV DNA ISH is more specific, these techniques conventionally utilize surgical biopsies. New tests using PCR to screen fine needle aspirates, saliva, brush cytology and serum for HPV are promising but have variable sensitivity and specificity. These non-invasive samples avoid the morbidity of surgical biopsies and need for tissue blocks; their clinical role in screening and surveillance remains largely untested. Further work is needed to validate these tests and define their role.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: What Is New in the 2017 WHO Blue Book for Tumors and Tumor-Like Lesions of the Neck and Lymph Nodes

The World Health Organization (WHO) 2017 Classification of Head and Neck Tumors ("Blue Book") will now include a new chapter on tumors and tumor-like lesions of the neck and lymph nodes, which was not included in the previous edition. Tumors and tumor-like lesions, including a variety of cysts and metastases, can arise in any component in the neck, including soft tissue, lymph nodes, and developmental remnants. The pathology and clinical features of metastatic carcinoma of unknown primary in the head and neck has changed dramatically in the last several years. Many of these tumors which were previously diagnosed as unknown primary are now identified as oropharyngeal and nasopharyngeal carcinomas related to human papillomavirus (HPV), less commonly to Epstein-Barr virus (EBV) and occasionally even to Merkel cell polyomavirus. Many unusual features can arise in these metastases, such as undifferentiated morphology, extensive cystic change with central degeneration, gland formation, and even ciliated cells. Rarely, carcinoma in the neck can arise in association with a heterotopic tissue, primarily thyroid or salivary gland tissue. Tumor-like lesions include branchial cleft cysts, thyroglossal duct cyst, dermoid and teratoid cyst, and ranula. Pathologists should be familiar with the diagnostic features and clinicopathologic corrections of these neck lesions in order to correctly diagnosis them and to provide for proper clinical management. This article will briefly describe the pathologic and clinical features of these entities as they are covered in the new 2017 Blue Book.