Sinonasal carcinomas characterized by rhabdoid/basaloid morphology and loss of expression of the SWI/SNF complex (SMARCB1, SMARCA4, SMARCA2), previously viewed as a subset of SNUCs, are recognized as a standalone entity in the 5th edition WHO Classification of Head and Neck Tumours [49]. The gene discussed is SMARCB1; the disease is nasal cavity and paranasal sinus carcinoma.