TACSTD2 and salivary duct carcinoma: No statistically significant difference in Trop-2 expression was found between the most prevalent SGC entities (adenoid cystic carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, adenocarcinoma NOS, salivary duct carcinoma, epithelial myoepithelial carcinoma and secretory carcinoma; p = 0.462).