SWI/SNF complex-deficient sinonasal carcinoma, defined by the loss of SMARCB1 or SMARCA4, was recently recognized as a distinct entity in the 5th edition of the World Health Organization (WHO) Classification of Head and Neck Tumors, highlighting its unique clinicopathologic and molecular profile [10]. The gene discussed is SMARCB1; the disease is nasal cavity and paranasal sinus carcinoma.