We demonstrate that tumors with SNUC morphology can be segregated to four distinct tumor types, including (1) sinonasal neuroendocrine carcinoma-like, IDH2 mutant, (2) sinonasal neuroendocrine carcinoma-like, SMARCA4/ARID1A enriched, (3) sinonasal carcinoma, SMARCB1 altered and (4) poorly differentiated adenoid cystic carcinoma. This evidence concerns the gene ARID1A and neoplasm.