ENTPD1 and salivary duct carcinoma: Moreover, a frequent CD39 expression on tumor cells was observed in rare entities included in the current cohort [3/3 epithelial–myoepithelial carcinoma (EMC), 3/3 salivary duct carcinoma (SDC), 3/3 basal cell adenocarcinoma (BCAC) and 2/2 myoepithelial carcinoma (MC)].