OVOL1 and salivary duct carcinoma: Adeno-NOS ex PA: adenocarcinoma, not otherwise specified ex pleomorphic adenoma; EMC ex PA: epithelial myoepithelial carcinoma ex pleomorphic adenoma; MC: myoepithelial carcinoma ex pleomorphic adenoma; OVOL1: ovo-like transcriptional repressor 1; SDC: salivary duct carcinoma ex pleomorphic adenoma; χ2: test statistic for association; *: significant difference (p < 0.05); N: total number of cases