Human papillomavirus-related carcinoma with adenoid cystic-like features: a series of five cases expanding the pathological spectrum

HPV-Related Multiphenotypic Sinonasal Carcinoma: A Clinicoradiological Series of 3 Cases With Full Endoscopic Surgical Outcome

Context: Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC), formerly known as HPV-related carcinoma with adenoid cystic like features, is a rare tumor subtype with unusual correlation between radiological, histopathological, and surgical findings. The shared histological characteristics with other sinonasal tumors make the diagnosis challenging. Optimal surgical and oncological treatments for this rare condition remains to be clearly defined. Methods: The objective of the study was to describe the unique characteristics and endoscopic surgical treatment of this rare tumor. In this retrospective case series, all patients with an HMSC diagnosis treated in our tertiary center were selected. Results: Three HMSC cases were identified, including 2 male and 1 female patients. All cases originated from the posterior nasal cavity. One case presented with a tumor of 8.9 cm × 6.4 cm × 8.7 cm, which is the largest tumor volume described to date. All patients received exclusively endoscopic surgical treatment, followed by adjuvant radiation therapy. No patient showed clinical or radiological sign of disease recurrence, or regional or distant metastasis, with a follow-up ranging from 9 months to 4 years. In 2 cases, initial diagnoses incorrectly suggested adenoid cystic or basaloid squamous cell carcinoma. HPV-DNA testing confirmed the presence of HPV in all cases, with identification of strains 16 and 18. Conclusion and Relevance: HMSC represents a newly identified diagnosis that constitutes a significant challenge for both clinicians and pathologists. It is crucial to acknowledge its indolent clinical course and the apparent contradiction between aggressive radiological features and the noninvasive nature of surgical findings. Skull base surgeons should be aware that, despite these complexities, endoscopic treatment is achievable in the majority of cases. This understanding is essential for the effective management of HMSC.

Evaluation of Some Prognostic Biomarkers in Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma

Background

Human papillomavirus (HPV)-related multi phenotypic sinonasal carcinoma (HMSC) is a recently described tumor subtype with an unknown prognosis, often misdiagnosed with other sinonasal carcinomas, and associated with high-risk HPV (HR-HPV). The present study aimed to evaluate the expression of vascular endothelial growth factor (VEGF), Bcl-2-associated X protein (BAX), epidermal growth factor receptors (EGFR), ProExTMC, and human telomerase reverse transcriptase (hTERT) and assess their association with survival and clinicopathological characteristics.

Methods

Between 2017 and 2022, 40 HMSC patients underwent surgical resection at the School of Medicine, Zagazig University Hospitals (Zagazig, Egypt). Tissue samples were examined for the presence of HR-HPV; absence of myeloblastosis (MYB), MYB proto-oncogene like 1 (MYBL1), and nuclear factor I/B (NFIB) fusions and the presence of myoepithelial proteins (calponin, S100, SMA), squamous differentiation markers (p63, p40, calponin), VEGF, BAX, ProExTMC, and hTERT by immunohistochemistry. All patients were followed up for about 54 months until death or the last known survival data. Data were analyzed using the Chi square test and Kaplan-Meier method.

Results

The expression of VEGF, hTERT, and ProExTMC was significantly associated with age, advanced tumor stages, lymph node metastasis, tumor size, mortality, relapse, poor disease-free survival (DFS), and overall survival (OS) (P<0.001). BAX expression was significantly associated with tumor size, age, poor DFS, and relapse (P=0.01, P<0.001, P=0.035, and P=0.002, respectively).

Conclusion

HMSC is strongly associated with HR-HPV. The expression of VEGF, EGFR, BAX, hTERT, and ProExTMC is associated with aggressive malignant behavior, poor survival, and poor prognosis, making them novel prognostic biomarkers for targeted therapeutics in HMSC.

Top 10 Basaloid Neoplasms of the Sinonasal Tract

BACKGROUND

Basaloid neoplasms of the sinonasal tract represent a significant group of tumors with histological overlap but often with different etiologies (i.e., viral, genetics), clinical management, and prognostic significance.

METHODS

Review.

RESULTS

"Basaloid" generally refers to cells with coarse chromatin in round nuclei and sparse cytoplasm, resembling cells of epithelial basal layers or imparting an "immature" appearance. Tumors with this characteristic in the sinonasal tract are represented by a spectrum of benign to high-grade malignant neoplasms, such as adenoid cystic carcinoma, NUT carcinoma, sinonasal undifferentiated carcinoma, SWI/SNF complex-deficient carcinomas, and adamantinoma-like Ewing sarcoma.

CONCLUSION

In some instances, histology alone may be sufficient for diagnosis. However, limited biopsy material or fine-needle aspiration specimens may be particularly challenging. Therefore, often other diagnostic procedures, including a combination of histology, immunohistochemistry (IHC), DNA and RNA testing, and molecular genetics are necessary to establish an accurate diagnosis.

Human papillomavirus-related multiphenotypic sinonasal carcinoma

Human papillomavirus-related multiphenotypic sinonasal carcinoma (HMSC) is a rare primary tumor of the sinonasal tract that has been reported recently. It is reportedly associated with human papillomavirus infection. The tumor presents with glandular cyst-like histology, but some cases exhibit squamous epithelialization and are positive on p16 immunohistochemical staining. The clinical picture and treatment of this disease have not been established. However, this report describes a recurrent case of this disease treated with salvage surgery. The patient was a 61-year-old woman who presented to the previous doctor with a chief complaint of nasal obstruction. A localized tumor was found in the left nasal cavity and was resected under endoscopic guidance. The postoperative pathological diagnosis was HMSC. Twenty-one months after the surgery, local recurrence was observed, and the patient was referred to our hospital. Since the recurrent lesion had widely infiltrated outside the nasal cavity, extensive resection and reconstructive surgery were performed. Postoperative radiotherapy was performed as an additional treatment. Notably, 13 months have passed since the salvage surgery, and no recurrence has been observed to date.

Human papillomavirus-related multiphenotypic sinonasal carcinoma: A report of two patients and review of the literature

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a recently described sinonasal tract tumor that is associated with high-risk HPV subtype infection. Despite histological features that are suggestive of a high-grade malignant tumor, the prognosis of HMSC is relatively good; however, the clinical features of this tumor are poorly understood. Here, we describe two patients with HMSC. The first was initially diagnosed with adenoid cystic carcinoma of the right nasal cavity; the tumor was extirpated via endoscopic endonasal surgery. Seventy-four months later, the tumor recurred in the right inferior turbinate and was diagnosed as HMSC after biopsy, whereupon it was resected en block via endoscopic endonasal surgery. No adjuvant therapy was administered during either episode; moreover, no recurrences have occurred during the 44 months since the second operation. The second patient was diagnosed with HMSC based on the biopsy of the tumor occupying the left nasal cavity. The tumor was completely resected under endoscopic endonasal surgery, and no adjuvant therapy was administered. There has been no recurrence for 15 months after the operation. Herein, we also review the clinical features of this tumor type based on 69 previously reported cases as well as our patients.

Mismatch Repair Deficiency and Somatic Mutations in Human Sinonasal Tumors

Simple Summary

Sinonasal carcinomas are rare tumors with an overall poor prognosis. Due to limitations in local therapeutic approaches, systemic neo-adjuvant or adjuvant therapies are becoming increasingly important in order to improve patient outcome. This study aimed to examine potentially therapeutic targetable molecular alterations in different sinonasal tumors, including deficiency in mismatch repair proteins and microsatellite instability as well as driver mutations. According to our results, immunohistochemical (IHC) analysis of mismatch repair (MMR) proteins and sequencing-based panel analysis should be integrated into the diagnostics of clinically aggressive inverted sinonasal papilloma (ISP) and sinonasal squamous cell carcinoma (SNSCC) in order to enable the therapeutic possibility of a targeted therapy.

Abstract

Due to limitations in local therapy approaches for sinonasal tumors, improvement in systemic therapies plays a pivotal role for prolongation of the patient’s survival. The aim of this study was to examine potential biomarkers, including deficiency in mismatch repair proteins (dMMR)/microsatellite instability (MSI-H) in sinonasal cancers and their precancerous lesions. A comprehensive analysis of 10 sinonasal cancer cell lines by whole exome sequencing, screening 174 sinonasal tumors by immunohistochemistry (IHC) for mismatch repair deficiency and next generation sequencing (NGS) of 136 tumor samples revealed a dMMR/MSI-H sinonasal squamous cell carcinoma (SNSCC) cell line based on a somatic missense mutation in MLH1 and an overall frequency of dMMR/MSI-H SNSCC of 3.2% (4/125). Targetable EGFR mutations were found in 89.3% (25/28) of inverted sinonasal papilloma (ISP) and in 60% (6/10) of ISP-associated carcinomas. While PIK3CA and EGFR mutations were not mutually exclusive, KRAS mutated tumors were an EGFR-wildtype. The effect of potential driver mutations in FGFR2, FGFR3, BRAF, HRAS, MAP2K1, PTEN, NOTCH1 and CARD11 need further investigation. Our results suggest that biomarker testing, including MMR-IHC and NGS panel analysis, should be integrated into the diagnostics of clinically aggressive ISPs and SNSCC to assess prognosis and facilitate therapeutic decisions.

DEK-AFF2 fusion-associated papillary squamous cell carcinoma of the sinonasal tract: clinicopathologic characterization of seven cases with deceptively bland morphology

A novel DEK-AFF2 fusion has been recently identified in four cases of basaloid to nonkeratinizing squamous cell carcinoma (SCC) in the sinonasal tract and middle ear with high-grade morphology. The exceptional response to immune checkpoint inhibitor in the first reported case highlights the potential clinical importance of identifying tumors with DEK-AFF2 fusions. We herein reported the first series of seven cases of DEK-AFF2 fusion-associated sinonasal SCC with deceptively bland morphology, including four cases of low-grade papillary Schneiderian carcinoma, which is a recently described tumor type with unknown molecular underpinnings. The DEK gene rearrangement was confirmed by DEK break-apart fluorescence in situ hybridization and DEK-AFF2 fusion transcripts were detected by reverse transcription polymerase chain reaction. In contrast to the previously reported DEK-AFF2 fusion-positive high-grade carcinomas, these tumors had a monotonous and bland morphology and were all initially diagnosed as sinonasal papilloma (SP) of various types, with or without dysplasia or carcinoma in situ. The tumor was characterized by mixed exophytic and inverted patterns, broad papillary fronds, acantholytic change, cellular monotony, dense neutrophilic infiltrates, and peripheral palisading. All tumors were diffusely positive for p40 or p63 and negative for NUT and p16. Molecular drivers associated with SP, including EGFR and KRAS mutations and both high and low-risk human papillomavirus infection, were negative in all cases. Although there was no overt stromal invasion or desmoplastic reaction in the initial specimens, these tumors tended to progress locoregionally through a prolonged clinical course and occasionally develop lymph node metastases, high-grade transformation, or extensively local destruction eventually leading to death. These justify more aggressive clinical management. Therefore, we propose the new terminology "DEK-AFF2 fusion-associated papillary SCC of the sinonasal tract" to better describe this clinicopathologically and molecularly distinct entity.

Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma-An Even Broader Tumor Entity?

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a recently defined tumor subtype with apparent favorable clinical outcome despite aggressive histomorphology. However, in recent years, additional numbers of cases, with more variable features and at locations outside the sinonasal region, have complicated the definition of HMSC. Here, we have performed a systematic review of all cases described so far in order to accumulate more knowledge. We identified 127 articles published between 2013 and 2021, of which 21 presented unique cases. In total, 79 unique patient cases were identified and their clinical and micromorphological nature are herein summarized. In our opinion, better clinical follow-up data and a more detailed tumor characterization are preferably needed before HMSC can finally be justified as its own tumor entity.

Impact of human papillomavirus in sinonasal cancer-a systematic review

BACKGROUND

Human papillomavirus (HPV) is an established prognostic marker in oropharyngeal squamous cell carcinoma. Currently, the role of HPV in sinonasal carcinoma is being explored.

OBJECTIVES

This systematic review addresses the role of HPV in sinonasal cancer, establishing the occurrence of HPV-positive cancers and the influence of HPV-positivity on prognosis in sinonasal cancer as well as the utility of the putative surrogate marker of HPV (p16) in sinonasal cancer.

MATERIAL AND METHODS

Studies were identified with searches of Medline via PubMed and Embase via OVID (4 May 2020). Articles on original research concerning sinonasal cancer and HPV in humans written in English were included. Case reports with less than five cases were excluded.

RESULTS

Initially, 545 articles were identified; 190 duplicate articles were removed leaving 355 articles for title/abstract screening. Title/abstract screening excluded 243 articles, leaving 112 studies assessed for eligibility. After full-text screening, 57 studies were included. All articles investigated the significance of HPV in sinonasal carcinomas. HPV was reported in approximately 30% of sinonasal squamous cell carcinoma (SNSCC), where it was associated with a better prognosis. In sinonasal cancer, p16 is associated with diagnostic pitfalls and a putative utility of p16 in SNSCC has yet to be established. HPV was not frequently reported in other types of sinonasal carcinomas, besides the recently described subtype, HPV-dependent Multiphenotypic Sinonasal Carcinoma. In other types of sinonasal carcinoma, HPV is not frequently found.

CONCLUSION

Approximately 30% of SNSCC are HPV-positive. HPV-positivity in SNSCC is associated with improved survival. HPV occurs only rarely in other sinonasal cancers. There is currently not sufficient evidence for p16 as a surrogate marker of HPV in SNSCC.

Sinonasal Squamous Cell Carcinoma: Etiology, Pathogenesis, and the Role of Human Papilloma Virus

PURPOSE OF REVIEW

Sinonasal squamous cell carcinoma (SNSCC) is a rare disease with considerable histologic diversity. Currently, there is a poor understanding of the etiology and pathogenesis of SNSCC. Here, we review recent literature to summarize what is known regarding (1) the etiology of SNSCC, (2) the role of Human Papilloma Virus (HPV) in SNSCC, and (2) the molecular underpinnings of SNSCC.

RECENT FINDINGS

1. High risk HPVappears to play a role in the pathogenesis of a subset of SNSCCs. SNSCCs with high risk HPV have improved survival compared with those without HPV and occur in patients who are younger, similar to HPV mediated oropharyngeal cancer. 2. A subset of inverted papillomas have transcriptionally active low-risk HPV and have a higher risk of transformation, while low risk HPV negative inverted papillomas frequently have EGFR mutations.

SUMMARY

SNSCC is a diverse disease with likely multiple etiologies including carcinogen, irritant exposure, and HPV. While not definitively proven, evidence supports a role for high-risk HPV in a subset of SNSCC, and low-risk HPV in a subset of inverted papillomas which transform to SNSCC. In-depth molecular and genomic studies are needed in SNSCC to better understand the genomic underpinnings and oncogenic drivers.

HPV-Related Multiphenotypic Sinonasal Carcinoma: A Case Report and Literature Review

OBJECTIVES

Human papilloma virus-related multi phenotypic sinonasal carcinoma (HMSC), a recently characterized sinonasal malignancy, is discussed including histology, clinical presentation, and treatment outcomes.

STUDY DESIGN

Case report with literature review.

METHODS

A case of HMSC is reported, as well as a retrospective review of all cases of HMSC reported in the English literature from January 2000 through May 2018 in the MEDLINE, EMBASE, and Scopus databases. Case data from selected articles was pooled along with the presented case and analyzed.

RESULTS

Including the present case report, a total of 57 cases of HMSC were identified through literature review. Of the 42 cases with staging information, 25 (60%) presented as early-stage disease (T1/T2). No nodal metastasis or disease-specific mortalities were reported. Among the 44 cases with posttreatment follow-up data, 16 cases (36.4%) developed local recurrence. The majority of recurrences occurred 24 to 60 months posttreatment, although reports of recurrence 10 and 29 years posttreatment exist. Local recurrence occurred in 40% and 60% of patients with perineural invasion and bone invasion, respectively. Patients who developed local recurrence had a longer disease-free interval when treated with adjuvant radiotherapy, which approached statistical significance.

CONCLUSIONS

HMSC is a distinct entity with paradoxically aggressive morphology paired with an indolent clinical course characterized by high rates of local recurrence but no reported disease-specific mortalities to date. Surgery with or without adjuvant radiotherapy is the most common treatment modality, and adjuvant radiotherapy may be associated with an increased disease-free interval among patients with local recurrence.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:106-110, 2021.

Human Papillomavirus Related Multiphenotypic Sinonasal Carcinoma: Report of a Case with Early and Progressive Metastatic Disease

Introduction  Human papillomavirus (HPV) related multiphenotypic sinonasal carcinoma (HMSC) is a newly described entity. The prognosis of this neoplasm is not well understood, but cases often demonstrate high-grade features and paradoxically indolent behavior.

Case Report  We present the case of a 65-year-old man referred with unilateral nasal congestion and epistaxis. Nasal endoscopy and imaging revealed an expansile mass filling the left nasal cavity. The patient underwent endoscopic-assisted medial maxillectomy, with complete resection and negative margins. Pathology revealed a basaloid tumor consisting of solid nests with multiple foci of cribriform architecture, with positivity for high-risk HPV, thus supporting the diagnosis of HMSC. Postoperatively, the patient received 66.6-Gy adjuvant three-dimensional proton therapy. Twenty-three months after surgical resection, he developed enlarging pulmonary nodules with biopsy features consistent with the primary sinonasal tumor. He was treated with three cycles of chemotherapy and eight cycles of immunotherapy, progressing on both therapies. He remains on palliative chemotherapy.

Conclusion  Here, we present a case of HMSC with early and progressive distant metastasis. We aim to add to an understanding of the behavior of this entity. Although this neoplasm may typically be indolent, further classification of high-risk features is necessary to identify rare aggressive cases.

HPV-Related Multiphenotypic Sinonasal Carcinoma: Four Cases that Expand the Morpho-Molecular Spectrum and Include Occupational Data

HPV-related multiphenotypic sinonasal carcinoma (HMSC) is a recently described distinct tumor entity of the sinonasal tract associated with high-risk subtypes of human papilloma virus (HPV), predominantly type 33. The biological behavior seems to be less aggressive than the often high-grade, highly proliferative morphology implies; however, recurrences are frequent. Most of the cases present as polypoid tumors within the nasal cavity. Microscopic morphology frequently encompasses adenoid cystic-like features or features reminiscent of other salivary gland tumors. Here, we describe four cases of this rare entity, all observed in women. The polypoid tumors were within the nasal cavity, leading to obstruction, facial pain and epistaxis. The morphology was predominantly basaloid, solid and adenoid cystic-like in two of four cases, one with additional glomeruloid features. Another case showed basaloid tumor cells with prominent mature squamous differentiation and extensive keratinization. A single case showed a predominantly solid and reticular growth pattern. All cases were diffusely positive for p16 (100%), expressed SOX10, LEF-1 and partially S-100, and harbored HPV high-risk types 33, 56 (2×) and 82. No recurrences or metastases were detectable after 3-50 months of follow-up. Of note, three of four patients were nurses/nursing assistant. We expand the morphological spectrum by describing a glomeruloid growth pattern and extensive mature keratinization, and add HPV type 82 to the molecular spectrum. The finding of HMSC among predominantly nurses in our cohort warrants further epidemiological studies in larger cohorts.

Translational genomics of sinonasal cancers

The sinonasal cavities harbor a wide variety of histologically distinct cancers, the majority very aggressive with 5-year survival rates between 30-60% and local recurrence as the main cause of death. This is a complex anatomic area, close to structures such the eyes and the brain, which is of special relevance for surgery and postoperative radiotherapy. The low incidence of these rare tumors hampers accumulation of experience with diagnosis and clinical managment as well as knowledge on recurrent genetic aberrations or testing of new treatment strategies. However, recent years have seen a growing number of publications on genetic aberrations providing data that can aid or fine-tune classification and provide molecular targets for treatment with specific inhibitors. In addition, new sinonasal cancer models are created that enable preclinical testing of candidate inhibitor drugs. With more and more novel targeted therapies being developed, options for personalized treatment of sinonasal cancer patients are now opening up.

HPV-Related Multiphenotypic Sinonasal Carcinoma: A Unique Case

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC), originally known as HPV-related carcinoma with adenoid cystic carcinoma-like features, is a recently described neoplasm that presents only in the sinonasal tract, displays features of both a surface-derived carcinoma and a salivary gland carcinoma, and is associated with high-risk HPV, specifically HPV type 33. Majority of the cases display high-grade histologic features, but HMSC paradoxically behaves in a relatively indolent fashion. Distinguishing HMSC from other histologic mimickers is essential as the management and prognosis are significantly different. In this article, we present a unique case of HMSC and review the literature.

Human Papillomavirus-Related Carcinoma With Adenoid Cystic-like Features of the Sinonasal Tract (Also Known as Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma)

Human papillomavirus (HPV)-related carcinoma with adenoid cystic-like features is a rare, recently recognized entity restricted to the sinonasal tract. By definition, it is associated with high-risk HPV infection, particularly with HPV type 33. In most cases, tumors are composed of dual cell populations, including predominant basaloid myoepithelial cells and usually inconspicuous ductal cells. Solid components with focal cribriform or tubular patterns, abrupt keratinization within tumor nests, and squamous dysplasia of the surface epithelium are characteristics of HPV-related carcinoma with adenoid cystic-like features. The immunohistochemistry of p16 followed by high-risk HPV testing may help in the differential diagnosis. Recent studies have demonstrated that the morphologic features of this entity are more diverse than initially believed. Surgical resection is the prime alternative for treatment. According to the limited data, the prognosis of this disease may be better than that of other sinonasal carcinomas.

Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma with Unique HPV type 52 Association: A Case Report with Review of Literature

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a recently described distinctive clinicopathologic entity defined by association to high risk HPV, localization to sinonasal tract and close histologic resemblance to salivary gland tumors. Lack of awareness of its pathologic features and biology among pathologists and oncologists make this entity susceptible to misdiagnosis and erroneous management. Herein, we illustrate a case of HMSC of the nasal cavity associated with heretofore unreported subtype HPV-52 and discuss the challenges associated with diagnosis and management of this rare tumor. A 48-year-old woman with intermittent epistaxis for 6 months presented with a nasal mass and underwent middle turbinectomy. Histology showed a tumor with features typical of adenoid cystic carcinoma (ACC) in the form of basaloid cells and cribriform architecture. However, careful inspection revealed findings uncommon in ACC; such as surface pagetoid tumor spread, areas of solid sheets of myoepithelial cells accompanied by increased mitotic figures which prompted immunohistochemistry. Multidirectional differentiation into ductal (CK7, AE1/AE3) and myoepithelial (p63, p40, S100, calponin) lineage together with strong and diffuse immunopositivity for p16 distinguished this tumor from ACC. HPV genotyping was positive for high risk HPV subtype HPV52, which confirmed the diagnosis of HMSC. HPV-related multiphenotypic sinonasal carcinoma is an under-recognized unique clinicopathologic entity that needs awareness to avoid mistaking it for commoner salivary gland tumors. Making accurate diagnosis of this newly-described tumor is imperative in order to understand its biology and to develop optimal therapeutic strategies.

Strong SOX10 expression in human papillomavirus-related multiphenotypic sinonasal carcinoma: report of 6 new cases validated by high-risk human papillomavirus mRNA in situ hybridization test

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is associated with high-risk HPV (HR-HPV) infection. Using HR-HPV messenger RNA (mRNA) in situ hybridization (ISH), we reported 6 new HMSC cases and compared their histopathology with that of sinonasal adenoid cystic carcinoma. Using p16 immunohistochemistry (IHC) and HR-HPV ISH, we retrospectively identified 6 HMSC cases. All HMSC cases were positive for HR-HPV mRNA ISH and p16 IHC. Two HMSC cases had overlying atypical squamous epithelium, and 1 had invasive squamous cell carcinoma (SCC). All HMSC cases were SOX10 positive, whereas the overlying atypical squamous epithelium and the SCC were SOX10 negative. One atypical HMSC-like case was also identified, which was positive for HR-HPV mRNA ISH, HR-HPV DNA ISH, and SOX10 IHC, but negative for p16 IHC. This study showed that HR-HPV mRNA ISH was a useful tool to diagnose HMSC and had stronger signals compared with HR-HPV DNA ISH. HR-HPV E6/E7 mRNA could be identified in the overlying atypical squamous epithelium and the invasive SCC. A combination of p16 and SOX10 IHC will be a useful screening panel for HMSC followed by confirmatory HR-HPV mRNA ISH test.