The spectrum of SWI/SNF-deficient sinonasal carcinomas currently includes the following: (1) SMARCB1-deficient sinonasal carcinoma, (2) SMARCB1-deficient sinonasal adenocarcinoma (with unequivocal glands or yolk–sac pattern), (3) SMARCA4 undifferentiated carcinoma, and (4) SMARCA4-deficient subset of teratocarcinosarcoma [51]. Here, SMARCA4 is linked to undifferentiated carcinoma.