KRT20 and carcinoid tumor: Prostate, kidney, and adrenocortical carcinomas as well as sarcomas, carcinoids, hepatocellular carcinomas and thymomas were negative for both CK7 and CK20 staining, while a large proportion of pancreatic and cholangiocarcinomas as well as some bladder and gastric tumours expressed both CK7 and CK20.