There are five different subtypes of SWI/SNF complex deficient sinonasal/base of skull malignancies, including SMARCB1-deficient sinonasal carcinoma; SMARCB1-deficient sinonasal adenocarcinoma; SMARCA4-deficient sinonasal carcinoma, a subset of SMARCA4-deficient teratocarcinosarcomas and poorly differentiated chordomas. This evidence concerns the gene SMARCB1 and chordoma.