Head and Neck Cytopathology: Human Papillomavirus-Positive Carcinomas, Including Diagnostic Updates, Testing Modalities, and Recommendations

Updates in head and neck cytopathology: Insights from European Congress of Pathology Short Course

Cytological specimens play a pivotal role in head and neck nodule/mass work up and diagnoses. The specimens´ importance has grown with the onset of personalized medicine and the routine use of molecular markers in the diagnostic work up. The Updates in Head and Neck Cytopathology Short Course ran during the 35th European Congress of Pathology held in Dublin, Ireland, in 2023 and brought together experts in cytopathology, pathology, and related fields to share their expertise and experience in the field of head and neck cytopathology and its future directions. Topics such as a one-stop clinic, the Milan System for Reporting Salivary Gland Cytopathology, next generation sequencing, and human papilloma virus detection in the head and neck area were covered during the short course. These topics are briefly summarized in the present review.

The Expression of HPV E6/E7 mRNA In Situ Hybridization in HPV Typing-negative Cervical Cancer

High-risk human papillomavirus (HPV) persistent infection is the major tumorigenesis factor for cervical cancer (CC). However, the incidence of HPV-negative CC is 5% to 30% with different HPV detection methods. High-risk HPV E6/E7 mRNA in situ hybridization (RISH) can detect HPV-driven tumors. Our study aimed to explore whether HPV typing-negative CC was caused by HPV infection. The tissues of CC patients with HPV typing results, collected from cervical biopsies, conization, or hysterectomies, were submitted to RISH using RNAscope chromogenicin. Immunohistochemistry was performed to evaluate the expression of p16INK4a and Ki-67. A total of 308 women with HPV typing results were enrolled, and 30 (9.74%) cases of HPV typing were negative. In HPV typing-negative CCs, 28/30 (93.3%) were positive for RISH, which contained 22/22 (100%) squamous cell carcinomas and 6/8 (75%) adenocarcinomas. RISH was positive in 278/278 (100%) HPV typing-positive CCs, which included 232/232 (100%) squamous cell carcinomas and 46/46 (100%) adenocarcinomas. Positive RISH in HPV typing-negative CC was significantly lower than in the HPV typing-positive group ( P =0.002, 95% confidence interval: 0.848-1.027). However, this significant difference only existed in adenocarcinoma. No significant differences were seen in the expression of p16INK4a and Ki-67 (all P >0.05). HPV typing may cause misdiagnosis in 9.74% of CC patients, and HPV E6/E7 mRNA can detect HPV in CC with HPV typing-negative patients. This approach could provide a novel option to accurately detect high-risk HPVs in cervical tumors and help to eliminate the percentage of misdiagnosed HPV-related cases.

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.

Detection accuracy of the Cobas HPV assay for high-risk HPV in head and neck FNA biopsy specimens

BACKGROUND

This study evaluated the detection accuracy of the Cobas human papillomavirus (HPV) assay for high-risk human papillomavirus (hrHPV) and HPV-16 in head and neck fine-needle aspiration (FNA) specimens with squamous cell carcinoma.

METHODS

Head and neck FNA biopsy specimens from 2012 to 2020 were retrospectively collected. Cobas HPV testing was performed on 90 FNA specimens with valid Cervista HPV testing results. Results of Cobas HPV and Cervista HPV assays were compared. A Linear Array or SPF10-LiPA25 HPV genotyping assay resolved cases with discrepant results. The κ value and accuracy of Cobas HPV testing were calculated. The accuracy of the Cobas HPV assay was also determined in 42 FNA needle-rinse specimens.

RESULTS

Cobas HPV was positive in 82% of the FNA specimens (74 of 90). The concordance between Cobas HPV and Cervista HPV test results was 88.9% (80 of 90) with substantial agreement (κ = 0.669; 95% CI, 0.481-0.856). With HPV genotyping confirmation in cases with discrepant results between the 2 HPV assays, Cobas HPV showed 100% sensitivity and specificity for hrHPV. HPV-16 was detected in 88% of HPV-positive cases (65 of 74). HPV genotyping confirmed 1 false-negative HPV-16 result and 1 false-positive HPV-16 result. Overall, the accuracy of Cobas HPV for HPV-16 was 97.8%. The accuracy of Cobas HPV in FNA needle-rinse specimens was 100%.

CONCLUSIONS

The Cobas HPV assay is highly accurate for determining the HPV status in head and neck FNA specimens. FNA needle rinse is valid for Cobas HPV testing in patients with squamous cell carcinoma.

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.

High-risk human papilloma virus was not detected in a Norwegian cohort of oral squamous cell carcinoma of the mobile tongue

OBJECTIVES

The presence of and the causative role of high-risk human papilloma virus (HPV) is a subject of controversy in oral squamous cell carcinoma (OSCC). The disagreement can be related to the misclassification of OSCC as oropharyngeal squamous cell carcinoma and/or lack of standard detection methods. This study aimed to examine the presence of transcriptionally active high-risk HPV in a homogenous Norwegian cohort of primary and second primary OSCC of the mobile tongue (oral tongue squamous cell carcinoma-OTSCC).

METHODS

Tissue microarrays containing formalin-fixed and paraffin-embedded cores of 146 OTSCC from the anterior 2/3 of the tongue (n = 128 primary and n = 18 second primary) from a multicentric Norwegian cohort were examined for the presence of high-risk HPV by DNA- and RNA-in situ hybridization (ISH) assays and p16 immunohistochemistry.

RESULTS

Transcriptionally active HPV (E6/E7 mRNA) was not identified in any of the OTSCC specimens. In parallel, no tumors were positive for HPV by DNA ISH. Although, 61 (42%) OTSCC demonstrated p16 positivity with varying staining intensity and subcellular localization, only two cases demonstrated strong and uniform p16-staining (both cytoplasmic and nuclear) in >70% of cancer cells. The absence of transcriptionally active high-risk HPV in this cohort of OTSCC indicates that high-risk HPV is an unlikely causative factor in the present material.

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.

HPV-related oropharyngeal cancer prevalence in a middle eastern population using E6/E7 PCR

Background

Given the paucity of data and widely variable rates that have been reported, the main objective of this study was to examine the prevalence of HPV-positivity in oropharyngeal squamous cell carcinoma (OPSCC) in Middle Eastern patients presenting to one of the region's largest tertiary care centers using polymerase chain reaction (PCR) amplification of the HPV E6/E7 oncogenes, a highly sensitive and specific method of detection.

Methods

Medical charts and archived pathological specimens were obtained for patients diagnosed with biopsy proven oropharyngeal cancer who presented to the American University of Beirut Medical Center between 1972 and 2017. DNA was extracted from paraffin-embedded specimens and tested for 30 high-risk and low-risk papilloma viruses using the PCR-based EUROarray HPV kit (EuroImmun).

Results

A total of 57 patients with oropharyngeal cancer were initially identified; only 34 met inclusion/exclusion criteria and were included in the present study. Most patients were males (73.5%) from Lebanon (79.4%). The most common primary tumor site was in the base of tongue (50%), followed by the tonsil (41.2%). The majority of patients (85.3%) tested positive for HPV DNA.

Conclusion

The prevalence of HPV-positivity amongst Middle Eastern OPSCC patients, specifically those from Lebanon, may be far greater than previously thought. The Lebanese population and other neighboring Middle Eastern countries may require a more vigilant approach towards HPV detection and awareness. On an international level, further research is required to better elucidate non-classical mechanisms of HPV exposure and transmission.

HPV-ISH-Negative Invasive Cervical Squamous Cell Carcinoma: Histologic and Pap Test Results

INTRODUCTION

A causal link between infection with a high-risk strain of human papilloma virus (hrHPV) and the development of cervical squamous cell carcinoma (SCC) is well established. However, a small number of SCCs are hrHPV-negative by either HPV co-DNA testing and/or HPV-in situ hybridization (HPV-ISH) at the time of diagnosis. These apparently hrHPV-negative lesions are poorly understood, specifically whether hrHPV-positive precursor lesions exist, which would be detected through hrHPV-based screening.

METHODS

A search of the pathology archives at the Johns Hopkins Hospital identified women with a diagnosis of hrHPV-negative cervical SCC on surgical specimen. All prior pathologies, including cervical cytology and surgical pathology specimens, and associated hrHPV DNA test results, p16 immunohistochemistry, and HPV-ISH were reviewed.

RESULTS

A total of 25 women were identified having a surgical specimen diagnosed as SCC with either negative or equivocal HPV-ISH. Fifteen had a Pap test in the 6 months preceding a diagnosis of SCC, with cytology diagnoses as follows: high-grade squamous intraepithelial lesion n = 14/15; atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion n = 1/15. hrHPV co-testing was performed for 5 of these 15 women and was negative in 2/5 cases. Cervical biopsy was performed for 24 women. HPV-ISH testing, performed on 14 of the biopsy specimens, was negative for 11/14 patients. Of 15 specimens stained for p16, 14 were positive.

CONCLUSION

A subset of patients exist in whom hrHPV is not detectable at or near the time of progression to SCC. Additional research is necessary to further describe this population and determine whether maintaining cytological screening would provide benefit.