Biphenotypic Sinonasal Sarcoma

Excerpt

Sinonasal malignancies only constitute 1-5% of head and neck malignancies but have a wide differential diagnosis and relatively non-specific symptoms. Sinonasal malignancies are most frequently diagnosed as squamous cell carcinoma (36 to 58%), followed by adenocarcinoma, mucosal melanoma, adenoid cystic carcinoma, and esthesioneuroblastoma. A lesser-known and recently classified entity is biphenotypic sinonasal carcinoma (BSNS), is reviewed in this topic. BSNS was first described in 2012 as "low-grade sinonasal sarcoma with neural and myogenic features" and was first recognized in the 2017 4th edition of the World Health Organization Classification of Head and Neck Tumors. Although it is a slow-growing and low-grade upper aerodigestive tract malignancy, BSNS is locally aggressive. About 20% of patients already have bony invasion at presentation in areas like the orbit (25%) and the cribriform plate (10%).

Cervical nodal metastasis is rarely demonstrated in any sinonasal malignancy and has not yet been demonstrated in patients with BSNS. The tumors can approach up to 4 cm and are most commonly found in the nasal cavity or ethmoid sinus, followed by the sphenoid sinus, in frequency. The maxillary sinus is the most common site for any sinonasal primary, but the ethmoid sinus contains the primary in 5 to 15% of patients. In BSNS, however, the incidence of ethmoid involvement is significantly greater but has not yet been quantified. Unlike squamous cell carcinoma, with an anticipated 5-year survival of only 25 to 50%, there have been no patients with BSNS who developed metastases, and only 1 death has been recorded in the literature. It is unclear what percentage of sinonasal malignancies are later diagnosed as BSNS, as the malignancy was previously classified under various entities, including but not limited to pseudofibrosarcoma, angiofibroma, and leiomyosarcoma. Just over 100 cases have been described in the existing literature, representing a combination of cases derived from retrospective reviews of specimens and more current case reports.