Induction chemotherapy response of HPV-related multiphenotypic sinonasal carcinoma: First-ever reported therapeutic outcome and a brief literature review.

A 54-year-old male patient complained of nasal obstruction and epistaxis for 2 years, with worsening of the symptoms in the preceding year. Physical examination revealed a friable, irregular mass, with yellowish secretion, in the left nasal fossa. Magnetic resonance imaging revealed an expansive lesion in the left nasal cavity, extending into the nasopharynx, ethmoid, right nasal cavity, and cortical bone of the hard palate. An incisional biopsy was then performed. Morphologically, a cellular malignant proliferation with a solid basaloid appearance admixed with adenoid cystic-like areas was observed. Immunohistochemistry revealed positivity for AE1/AE3, CK7, p63, and calponin, with focal labeling for CD117 and α-SMA. p16 had diffuse cytoplasmic and nuclear positivity. Ki-67 index was >80%. Given the morphological and immunohistochemical aspects, the diagnosis was conclusive for HPV-related multiphenotypic sinonasal carcinoma. The tumor was considered irresectable, and the patient was submitted to induction chemotherapy with docetaxel, cisplatin, and infusional 5-fluorouracil, with significant regression after therapy, followed by chemoradiotherapy with carboplatin, without limiting toxicities. The patient is currently under regular follow-up, with complete clinical and radiological response. To date, there are no reports in the literature of induction chemotherapy use or its complete therapeutic responsiveness related to this lesion. A brief literature review was included with the main epidemiological, clinical, therapeutic, and prognostic aspects regarding the 85 cases reported in the literature, including ours.