Membranous and cytoplasmic expression of PD-L1 protein was detected in four types of PNETs, including SCLC (n = 48, 66.7%), LCNEC (n = 21, 29.2%), AC (n = 0, 0.0%), and TC (n = 3, 4.1%). Here, CD274 is linked to small cell lung carcinoma.