Synchronous yet distinct HPV-associated sinonasal carcinomas on an immune-dysfunctional background.

Human papillomavirus (HPV)-associated multiphenotypic sinonasal carcinoma (HMSC) is a relatively new classification of head and neck carcinomas that displays histological combinations of multiple different neoplasms. Despite their high-grade appearance, the disease course is often indolent. Here, we report a unique case of HMSC in which a patient with a prior history of sarcoidosis presented with two histologically, and anatomically distinct tumors in the sinonasal tract. One of the tumors was denoted as HMSC, and the other resembled a nonkeratinizing squamous cell carcinoma. Importantly, these two tumors were both found to be driven by the same high-risk HPV strain, HPV45, which has not been reported previously in HMSC. In this patient, it is important to note that the concomitant diagnosis of malignancy and sarcoidosis makes disease monitoring challenging, given the ability of sarcoidotic nodules to mimic the metabolic characteristics of tumors on PET scans.