HPV-related Multiphenotypic Sinonasal Carcinoma: An Expanded Series of 49 Cases of the Tumor Formerly Known as HPV-related Carcinoma With Adenoid Cystic Carcinoma-like Features

Poorly differentiated neuroendocrine carcinoma of the head and neck: human papillomavirus tumour status/p16 status and impact on overall survival

AIMS

Poorly differentiated neuroendocrine carcinoma (PDNEC) of the head and neck is a rare high-grade neuroendocrine neoplasm. Human papillomavirus (HPV) status and p16 status are as yet unclear among PDNECs, owing to a lack of statistical analysis. The objective of the present study was therefore to evaluate their potential clinicopathological associations, and their prognostic impact on overall survival in PDNECs of the head and neck, regardless to HPV genotype.

METHODS AND RESULTS

All cases of PDNEC of the head and neck between 1998 and 2019 were identified from the database of the Lyon university hospital pathology department (n = 21); for these cases, p16 immunohistochemistry and HPV in-situ hybridisation were performed. Published cases of PDNEC of the head and neck with assessment of HPV status and p16 status were identified in PubMed (n = 57). Local and published cases were pooled for analysis. HPV positive (HPV+) tumour status was found to be significantly associated with oropharyngeal localisation (P < 0.001) and overexpression of p16 (P < 0.001). Multivariate analysis, adjusted on tumour site, histological subtype, p16 status, HPV status, and source of the case, showed that oropharyngeal localisation [hazard ratio (HR) 3.031, 95% confidence interval (CI) 1.257-7.310] and being a small-cell variant (HR 2.859, 95% CI 1.150-7.109) were significant predictors of worse overall survival; HPV+ tumour status was associated with better overall survival (HR 0.388, 95% CI 0.146-0.995).

CONCLUSIONS

HPV+ tumour status was associated with oropharyngeal PDNECs and with a better prognosis.

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.

Diagnostic traps awaiting the head/neck pathologist: "Cytoplasm-poor" neoplasms

CONTEXT

Beyond squamous carcinoma, a variety of diagnostically challenging neoplasms arise within various head and neck sites. This is particularly the situation with neoplasms where little cellular cytoplasm is present to assist the pathologist in categorizing such lesions.

OBJECTIVE

To highlight diagnostic pitfalls that accompanying neoplasms composed primarily of 'cytoplasmically-poor' cells. These pitfalls include morphologic and immunohistochemical traps that emerge from this class of neoplasms.

DATA SOURCES

Selection of pathologic specimens from the author's personal files, and literature review.

CONCLUSIONS

Interpretative pitfalls regarding the histopathology and immunophenotype of small 'cytoplasmically-poor' neoplasms are a diagnostic hazard in head and neck surgical pathology practice, and require knowledge of histomorphologic plasticity and aberrant immunophenotyping.

Immunohistochemical Detection and Molecular Characterization of IDH-mutant Sinonasal Undifferentiated Carcinomas

Recent studies have identified recurrent isocitrate dehydrogenase 2 (IDH2) mutations in a subset of sinonasal undifferentiated carcinomas (SNUCs); however, the true frequency of IDH mutations in SNUC is unknown. We evaluated the utility of mutation-specific IDH1/2 immunohistochemistry (IHC) in a large multi-institutional cohort of SNUC and morphologic mimics. IHC using a multispecific antibody for IDH1/2 (R132/R172) mutant protein was performed on 193 sinonasal tumors including: 53 SNUCs, 8 poorly differentiated carcinomas (PDCARs) and 132 histologic mimics. Mutant IDH1/2 IHC was positive in 26/53 SNUCs (49%; 20 strongly positive and 6 weak) and 3/8 PDCARs (37.5%; 2 strong; 1 weak) but was absent in all other tumor types (0/132). Targeted next-generation sequencing (NGS) on a subset of SNUC/PDCAR (6 strong and 3 weak positive for IDH1/2 IHC; 7 negative) showed frequent IDH2 R172X mutations (10/16) and a single IDH1 R132C mutation. All 6 cases with strong positive mutant IDH1/2 staining and NGS had IDH2 R172S/G mutations. The 3 IHC-weak cases all had IDH2 R172T mutations. Among the 7 tested cases that were negative for mutant IDH1/2 IHC, NGS detected 1 case each with IDH2 R172T and IDH1 R132C mutation. IDH-mutant carcinomas also had frequent mutations in TP53 (55%) and activating mutations in KIT (45%) or the PI3K pathway (36%). Mutation-specific IDH1/2 IHC identifies IDH mutations in SNUC, however, it lacks sensitivity for the full range of IDH mutations. These findings suggest that IDH-mutant sinonasal carcinoma may represent a distinct pathobiological entity with therapeutic implications that can be identified by a combined approach of multispecific IDH1/2 IHC and sequencing.

Mammary Analog Secretory Carcinoma of the Nasal Cavity: Characterization of 2 Cases and Their Distinction From Other Low-grade Sinonasal Adenocarcinomas

Secretory carcinoma, originally described as mammary analog secretory carcinoma (MASC), is a low-grade salivary gland tumor characterized by a t(12;15)(p13;q25) translocation, resulting in an ETV6-NTRK3 gene fusion. Most MASCs are localized to the parotid gland and intraoral minor salivary glands. Moreover, ETV6-rearranged carcinomas with secretory features have been reported recently in the thyroid (with and without a history of radiation exposure), skin, and in very rare instances in the sinonasal tract. Here, we describe 2 cases of primary MASC in the sinonasal tract and provide a detailed clinical and histopathologic characterization of their morphology, immunohistochemical profile, and genetic background and highlight features allowing for its separation from its recently described molecular mimicker, ETV6-rearranged low-grade sinonasal adenocarcinoma.

Imaging Review of New and Emerging Sinonasal Tumors and Tumor-Like Entities from the Fourth Edition of the World Health Organization Classification of Head and Neck Tumors

The sinonasal tract is an environment diverse with neoplasia. Given the continued discovery of entities generally specific to the sinonasal tract, the fourth edition of the World Health Organization Classification of Head and Neck Tumors was released in 2017. It describes 3 new, well-defined entities and several less-defined, emerging entities. The new entities are seromucinous hamartomas, nuclear protein in testis carcinomas, and biphenotypic sinonasal sarcomas. Emerging entities include human papillomavirus-related sinonasal carcinomas, SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1-deficient sinonasal carcinomas, renal cell-like adenocarcinomas, and chondromesenchymal hamartomas. The literature thus far largely focuses on the pathology of these entities. Our goal in this report was to familiarize radiologists with these new diagnoses and to provide available information regarding their imaging appearances.

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.

An update on head and neck cancer: new entities and their histopathology, molecular background, treatment, and outcome

The head and neck region harbor numerous specialized tissues of all lineages giving rise to a plethora of different malignancies. In recent years, new types and subtypes of cancer has been described here due to the recognition of their histological and molecular characteristics. Some have been formally accepted in the most recent classifications from the World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) as distinct diseases due to characteristics in clinical presentation, outcome, and treatment. In particular, this applies to malignancies of the salivary gland, sinonasal tract, and oropharynx. In this overview, we present the most recent developments in the classification, histopathological characteristics, and molecular features of head and neck cancer. The clinical and radiological characteristics, outcome, and treatment options including perspectives for targeted therapies, are discussed.

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.

Adamantinoma-Like Ewing Sarcoma of the Thyroid: A Case Report and Review of the Literature

Currently considered a variant of Ewing sarcoma, adamantinoma-like Ewing sarcoma is a rare malignancy that shows classic Ewing sarcoma-associated gene fusions but also epithelial differentiation. Here we present the 6th reported case of adamantinoma-like Ewing sarcoma involving the thyroid gland. Sections of the thyroid tumor from a 20-year old woman showed sheets, lobules and trabeculae of primitive, uniform, small round blue cells that diffusely expressed pankeratin, p40 and CD99. Fluorescent in situ hybridization revealed an EWSR1 gene rearrangement and an EWSR1-FLI1 fusion was detected by RT-PCR. Neck lymph nodes were not involved, and the patient was treated with a Ewing sarcoma chemotherapy protocol and radiation and is disease free 7 months after surgery. The unusual histology and immunohistochemical profile of adamantinoma-like Ewing sarcoma makes diagnosis and classification very challenging. We also present a literature review of adamantinoma-like Ewing sarcoma involving the thyroid.

Comprehensive analysis of HPV infection, EGFR exon 20 mutations and LINE1 hypomethylation as risk factors for malignant transformation of sinonasal-inverted papilloma to squamous cell carcinoma

Different risk factors are suspected to be involved in malignant transformation of sinonasal papillomas and include HPV infection, tobacco smoking, occupational exposure, EGFR/KRAS mutations and DNA methylation alterations. In our study, 25 inverted sinonasal papillomas (ISPs), 5 oncocytic sinonasal papillomas (OSP) and 35 squamous cell carcinomas (SCCs) from 54 patients were genotyped for 10 genes involved in EGFR signalling. HPV-DNA detection was performed by in-situ hybridisation and LINE-1 methylation was quantitatively determined by bisulphite-pyrosequencing. High-risk HPV was observed only in 13% of ISP-associated SCC and in 8% of de novo-SCC patients. EGFR mutations occurred in 72% of ISPs, 30% of ISP-associated SCCs and 17% of de novo-SCCs. At 5-year follow-up, SCC arose in only 30% (6/20) of patients with EGFR-mutated ISPs compared to 76% (13/17) of patients with EGFR-wild-type ISP (p = 0.0044). LINE-1 hypomethylation significantly increased from papilloma/early stage SCC to advanced stage SCC (p = 0.03) and was associated with occupational exposure (p = 0.01) and worse prognosis (p = 0.09). In conclusion, our results suggest that a small subset of these tumours could be related to HPV infection; EGFR mutations characterise those ISPs with a lower risk of developing into SCC; LINE-1 hypomethylation is associated with occupational exposure and could identify more aggressive nasal SCC.

High-grade myoepithelial carcinoma can show histologically undifferentiated/anaplastic features

High grade malignant tumors with a poorly-/un-differentiated morphology pose significant diagnostic challenges. Increasingly, the use of adjunct immunohistochemical and molecular tests to characterize and delineate the histopathologic phenotype of these tumors has become necessary, particularly in head and neck tumors. Recently, several entities with a poorly-/un-differentiated light microscopic morphology have been defined based on specific immunohistochemical and genetic characteristics. We herein describe two cases of high-grade myoepithelial carcinoma, one occurring in the submandibular gland and the other occurring in the left nasal cavity, both showing undifferentiated histological and anaplastic cytomorphological features. This led to very broad differential diagnostic considerations and the diagnosis was only established after extensive immunohistochemical studies. Molecular testing for HPV was negative in both cases. Gene fusion analysis using a targeted sequencing assay (Archer® FusionPlex® system) did not identify fusions involving PLAG1, HMGA2, EWSR1 or ALK genes in either case. The submandibular tumor showed an aggressive clinical course, with diffuse pulmonary metastases at presentation, whilst the nasal cavity tumor showed only localized disease. Awareness of a subcategory of high-grade myoepithelial carcinomas with undifferentiated light microscopical features is of significant importance in antibody selection for immunohistochemical investigation of poorly-/undifferentiated malignant tumors in the head and neck region. This histological variant of myoepithelial carcinoma adds to the growing list of differential diagnoses in this diagnostically complex and multifaceted field.

Data Set for the Reporting of Carcinomas of the Nasal Cavity and Paranasal Sinuses: Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting

The International Collaboration on Cancer Reporting was established to internationally unify and standardize the pathologic reporting of cancers based on collected evidence, as well as to allow systematic multi-institutional intercountry data collection to guide cancer care in the future. This data set has been developed by the collaborative efforts of an international multidisciplinary panel of experts involved in the care of patients with carcinomas of the nasal cavity and paranasal sinuses (sinonasal tract). The nasal cavity and paranasal sinuses (including frontal, sphenoid, ethmoid, and maxillary sinuses) comprise a very complex anatomic area of the head and neck, affected by a sometimes bewildering array of neoplasms. Management of malignancies in this anatomic region involves complex surgery because of the anatomic confines and close proximity to many vital structures. Given a multidisciplinary approach, the standardized reporting of the carcinomas that develop in this anatomic region include both required (core) and recommended (noncore) elements in pathology reporting in order to be able to identify critical prognostic factors, often requiring clinical and radiologic correlation. A summary of the International Collaboration on Cancer Reporting guidelines and clinically relevant elements, along with additional explanatory notes, are provided, based on evidentiary support from the literature, set in the context of practical application.

SOX10 Immunoexpression in Basaloid Squamous Cell Carcinomas: A Diagnostic Pitfall for Ruling out Salivary Differentiation

SOX10 immunoexpression is increasingly recognized in salivary gland tumors, including but not limited to those with myoepithelial, serous acinar, and intercalated duct differentiation. However, SOX10 expression has not been extensively evaluated in other epithelial tumors that can mimic salivary origin. Basaloid squamous cell carcinoma (SCC) is a unique variant of SCC that shows morphologic overlap with several salivary tumors, including adenoid cystic carcinoma, basal cell adenocarcinoma, and myoepithelial carcinoma. We performed SOX10 immunohistochemistry on 22 basaloid SCCs and 280 non-basaloid SCCs. If tissue was available, we also performed immunohistochemistry for S100 and p16, and in-situ hybridization for high-risk HPV RNA. SOX10 was positive in 13/22 basaloid SCCs (59%), including 5/6 (83%) that were HPV-positive and 6/12 (50%) that were HPV-negative. Only 2/12 basaloid SCC (17%) demonstrated focal S100 expression. All non-basaloid SCCs were SOX10 negative. Frequent positivity for SOX10 in basaloid SCC presents a significant diagnostic pitfall for distinguishing these tumors from various basaloid salivary carcinomas. The preponderance of SOX10 expression in the basaloid variant of HPV-positive SCC also presents a diagnostic challenge in separating it from HPV-related multiphenotypic sinonasal carcinoma. SOX10 may be more broadly considered a marker of basal differentiation and should not be assumed to be specific for salivary origin in epithelial head and neck tumors.

Ciliated HPV-Related Carcinoma: A Diagnostic Challenge on Frozen Section

Oropharyngeal squamous cell carcinomas associated with high risk HPV show a wide morphological spectrum, including papillary, adenosquamous, lymphoepithelioma-like and sarcomatoid. We report an interesting case of ciliated HPV-related carcinoma arising from tonsillar tissue in a 55-year-old man which was associated with HPV33. This rare variant has been described in only a handful of cases in the literature, and to our knowledge this is the first case specifically associated with HPV33. The presence of cilia is a potential diagnostic problem as it has been traditionally considered a feature of benignancy, and could pose a particular challenge on frozen section. The diagnostic challenges, differential diagnosis of this tumor and the association with HPV33 are discussed.

Current status of clinical testing for human papillomavirus in oropharyngeal squamous cell carcinoma

While a variety of human papillomavirus (HPV) tests and surrogate markers are available, currently there is no consensus on the best detection method(s) that should be used to identify HPV-related oropharyngeal squamous cell carcinomas and serve as a standard test (or tests) for routine diagnostic use. As we begin to consider using the results of HPV testing for clinical purposes beyond simple prognostication, such as making decisions on treatment dose or duration or for targeted therapies that may be highly dependent on viral-mediated pathways, we need to be more rigorous in assessing and ensuring the performance of the test (or tests) used. Here we provide an overview of the platforms and technologies, including the strengths and limitations of each test, and discuss what steps are needed to generate confidence in their performance for use in clinical practice.

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.

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

Oropharyngeal squamous cell carcinoma caused by transcriptionally active human papillomavirus (HPV) is now well established as a unique form of head and neck cancer. Given the high frequency of metastasis to cervical lymph nodes by HPV-positive oropharyngeal squamous cell carcinomas, fine-needle aspiration (FNA) represents a widely accepted method for the sampling and diagnosis of these cancers. The recently published College of American Pathologists Guideline (2017) provides recommendations for the effective performance and interpretation of high-risk (HR) HPV testing in head and neck squamous cell carcinoma (HNSCC), including testing on FNA samples of metastatic HNSCC to cervical lymph nodes. There is a wide range of options available for HR-HPV testing in cytologic specimens.

Adenoid cystic carcinoma with myoepithelial predominance affecting maxilla and maxillary sinus

Adenoid cystic carcinoma (ACC) represents less than 10% of all salivary gland tumors, rarely occurring centrally in the jaws. Herein we describe the case of a 36-year-old female patient presenting a painless swelling in the right maxilla, resulting in marked facial asymmetry. Intra-orally it was observed a swelling covered by an erythematous and irregular-surfaced mucosa, affecting the gingiva and crossing the midline of the hard palate. Imaging studies showed a mixed radiolucent-radiopaque lesion with ill-defined borders, involving the right side of the maxilla and the maxillary sinus. Incisional biopsy revealed basophilic cribriform tumoral islands and solid sheets of neoplastic cells invading bone trabeculae. Most of the tumoral cells presented myoepithelial characteristics, while few true luminal/epithelial cells were observed. To illustrate the epithelial-myoepithelial pattern, immunohistochemical reactions were performed, as well as double immunohistochemical staining. The diagnosis was intraosseous ACC, which features were discussed as well as the potential differential diagnosis.

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.

Consistent LEF-1 and MYB Immunohistochemical Expression in Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma: A Potential Diagnostic Pitfall

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC) is a distinct, newly-described sinonasal tract neoplasm characterized by a salivary gland tumor-like appearance with myoepithelial and ductal cells, frequent surface squamous dysplasia, and relatively indolent behavior. When considering a diagnosis of HMSC, aggressive high-grade salivary gland carcinomas, particularly those with a basaloid morphology such as basal cell adenocarcinoma and adenoid cystic carcinoma, enter the differential diagnosis. The full morphologic and immunophenotypic profile of HMSC continues to be unraveled. In this series of ten cases, we demonstrate that this tumor has consistent, strong immunohistochemical expression of LEF-1 yet lacks nuclear expression of β-catenin, and also has consistent yet variable expression of MYB protein. While LEF-1 expression may be a useful diagnostic adjunct, it can also be a pitfall, as other salivary tumors such as basal cell adenocarcinoma have been previously shown to express LEF-1. Additionally, MYB protein expression is not a discriminatory marker when trying to separate HMSC from adenoid cystic carcinoma.

Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma: A Case Report Documenting the Potential for Very Late Tumor Recurrence

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma is a peculiar sinonasal tract tumor that demonstrates features of both a surface-derived and salivary gland carcinoma. Implicit in its name, this tumor has a consistent association with high-risk HPV, particularly type 33. It was first described in 2013 under the designation of HPV-related carcinoma with adenoid cystic carcinoma-like features. However, since its initial description additional cases have emerged which demonstrate a wide morphologic spectrum and relatively indolent clinical behavior. Herein we report our experience with a case of HPV-related multiphenotypic sinonasal carcinoma that was initially classified as adenoid cystic carcinoma in the 1980s. The patient recurred after a 30-year disease free interval. RNA in situ hybridization confirmed the presence of high-risk HPV in both her recurrence and her initial tumor in the 1980s, which allowed for reclassification as HPV-related multiphenotypic sinonasal carcinoma. Our case adds to the literature of this relatively newly described entity and supports the indolent clinical behavior of this neoplasm but also demonstrates a potential for very late local recurrence.