A Rare Sinonasal Malignancy: Biphenotypic Sinonasal Sarcoma.

Biphenotypic sinonasal sarcoma (BSNS), which has been described in the recent years, is a low-grade spindle cell sinonasal sarcoma characterized by rare neural and myogenic features. It has a slow growth pattern; does not metastasize, but local recurrences are common after surgery. Non-specificity of examination findings and symptoms and similarities of its histopathological features with other spindle cell sarcomas, neural tumors, and skeletal muscle-derived tumors involving the nasal cavity make the diagnosis difficult. Therefore, histopathological features should be evaluated together with immunophenotyping and molecular studies for differential diagnosis. There are very few BSNS cases or case series in the literature. In this report, we reported our clinical approach to a case with BSNS in the right nasal cavity and the histopathological features of the disease in the light of the current literature.