CD274 and carcinoma: Witte et al. investigated PD-L1 expression on ICs in 94 head and neck salivary gland carcinomas including 41 ACCs, 21 MECs, 16 acinic cell carcinomas, 12 adenocarcinomas not otherwise specified, 2 epithelial-myoepithelial carcinomas, one salivary duct carcinoma, and one carcinoma ex pleomorphic adenoma.