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.