SMARCB1 and sinonasal undifferentiated carcinoma: In contrast, adenoid cystic carcinoma, adenocarcinoma, sinonasal undifferentiated carcinoma with a loss of the SMARC-B1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily b, member 1) gene, and olfactory neuroblastoma each represented one case (8%) among all malignant tumours.