Human Papillomavirus-Associated Combined Neuroendocrine and Squamous Cell Carcinoma of the Sinonasal Tract

Abstract

Combined neuroendocrine and squamous cell carcinoma (SCC) of the sinonasal tract is rare entity but is increasingly gaining recognition within the head and neck pathology community. In a recent series, a single case was reported to demonstrate diffuse p16 positivity despite lacking high-risk human papillomavirus (HPV) by RNA in-situ hybridisation (ISH). Here we describe a case of p16 positive combined neuroendocrine and SCC containing high-risk HPV. Retrospective case review of sinonasal carcinomas within the Head and Neck Pathology Department at Guy’s and St Thomas’ NHS Foundation Trust identified a single case of combined neuroendocrine and SCC. Clinico-demographic data was obtained through electronic hospital records. All immunohistochemistry and in-situ hybridisation were undertaken according to departmental standard operating procedures. Routine microscopy showed the tumour to comprise small and large cell neuroendocrine components as well as squamous and spindle cell elements. Small and large cells demonstrated CD56 and synaptophysin expression, whereas CK5/6 and p63 were confined to squamous components. There was diffuse p16 expression and punctate nuclear positivity for DNA ISH. We describe a case of HPV-associated combined neuroendocrine and SCC of the sinonasal tract. Recognition of HPV association with this entity avoids diagnostic pitfalls.

To the Editors,

Agarwal and colleagues are to be commended for presenting their series of combined neuroendocrine and squamous cell carcinomas (SCC) of the sinonasal tract and for highlighting the diagnostic challenges associated with this rare entity [1]. In Case 3 of their series, the authors demonstrate diffuse staining for p16 immunohistochemistry, but high-risk human papillomavirus (HPV) was negative by RNA in-situ hybridisation. The findings of Agarwal et al. support recent reports indicating the suboptimal specificity of p16 as a surrogate for transcriptionally active oncogenic HPV in the sinonasal tract [2]. This tumour was of particular interest to us since it shares several similar features to a recent case from our files.

In our case, a 50-year-old female patient presented with right-sided facial discomfort and epiphora. Clinical and radiographic examination revealed a polypoid lesion of 3.6 cm extending from the right superior meatus and ethmoid region to completely obstruct the right nasal cavity (Fig. 1A). Routine microscopy of the surgically debulked specimen showed most of the tumour to comprise sheets and broad interconnecting trabeculae of cells with small hyperchromatic polygonal nuclei (Fig. 1B, C). Nodular foci of cells with larger nuclei demonstrating a speckled chromatin pattern were evident (Fig. 1D) and there was transition to areas with squamous morphology (Fig. 1E). A malignant spindle cell element was also evident and largely demarcated from the small cell component (Figs. 1D–F), but showed focal continuity with the large and squamous cell areas. There was no glandular differentiation.

Fig. 1.

Radiological, histological, immunohistochemical and high-risk HPV in situ hybridisation features. A Mid-face coronal plane CT demonstrating the mass obstructing the right nasal cavity. B Low magnification view demonstrating hyperchromatic tumour cells arranged in sheets and interconnecting broad trabeculae, H&E. C High magnification of the dominant component demonstrating polygonal nuclei, H&E. D Medium magnification view demonstrating foci of abrupt transition to foci of larger and paler staining tumour cell nuclei, H&E. E High magnification of squamous areas, H&E. F Trabeculae of the dominant hyperchromatic small cell component juxtaposed against the malignant spindle cells. G Pan-cytokeratin highlights both the large cell and squamous areas, being negative elsewhere. H and I Cytokeratin 5/6 and p63, respectively, both restricted to areas of clear squamous differentiation. J CD56 positivity in both the small and large cell populations. K and L NSE and synaptophysin, respectively, restricted to the small cell component. M Ki-67 demonstrating a very high proliferation index (> 70%). N Strong and diffuse p16 positivity. O High-risk HPV DNA in situ hybridisation

Pan-cytokeratin (clone AE1/AE3, Dako) immunohistochemistry was variable and largely confined to the large cell and squamous components (Fig. 1A), the latter were highlighted by cytokeratin 5/6 (clone D5/16 B4, Dako) and p63 (clone 4A4, Biocare) (Fig. 1B, C, respectively). Small and large cells stained diffusely for CD56 (clone CD546, Leica Biosystems) (Fig. 1D), whereas neuron specific enolase (NSE, clone BBS/NC/VI-H14, Dako) and synaptophysin (clone DAK-SYNAP, Dako) were limited to small cells (Fig. 1E, F). All elements demonstrated a brisk Ki-67 (clone MIB-1, Dako) proliferation index of > 70% (Fig. 1G) and there was diffuse nuclear and cytoplasmic positivity for p16 (clone E6H4, Roche Ventana) (Fig. 1H). By contrast to the report by Agarwal et al. our case showed punctate nuclear positivity for high-risk HPV by DNA in-situ hybridisation (INFORM HPV III Family 16 probe, Ventana) (Fig. 1I). Real-time polymerase chain reaction (qPCR, VenusHPV, Liferiver) identified the presence of HPV18. Our final diagnosis was HPV-associated carcinoma with neuroendocrine and squamous differentiation, and the patient was commenced on induction chemotherapy. Part way through treatment, a lung nodule was detected, and the patient died of disease 9 months after diagnosis.

HPV is now recognised to be associated with a subgroup of sinonasal nonkeratinizing SCC but have also been separately reported in sinonasal neuroendocrine carcinomas [3–5]. Here we report an HPV-associated combined neuroendocrine and squamous cell carcinoma, which to our knowledge is the first reported case in the literature. Our findings add to the growing number of HPV-associated carcinoma subtypes in the head and neck. Furthermore, against the background of increasing evidence for improved survival in HPV-associated sinonasal SCC, we feel that it is important to recognise that the virus may also be associated with combined neuroendocrine and SCC since the presence of the former may abrogate any survival advantage [5–9].

Author Contributions

SJB and ST were equally involved in the case concept, data acquisition, interpretation, and manuscript preparation.

Funding

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Declarations

Conflict of interest

Authors declare that they have no conflict of interest.

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No patient personal data/identifiers are disclosed; hence, no consent was necessary.