This study aimed to systematically investigate SWI/SNF complex-deficient sinonasal tract carcinomas in a single-institution cohort, perform clinicopathologic characterization, and explore the underlying molecular mechanisms of SMARCB1 and EWSR1 gene abnormalities in SMACRB1-deficient sinonasal carcinomas. The gene discussed is EWSR1; the disease is nasal cavity and paranasal sinus carcinoma.