CK20

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

Anti-cytokeratin 20 antibody reacts primarily with gastric and intestinal epithelium as well as urothelium. It is most useful, especially when combined with cytokeratin 7, in identifying adenocarcinomas from these sites. CK20 is expressed in a majority of adenocarcinomas from colorectal, urothelial, and mucinous ovarian origin, and, to a lesser extent, from gastric, biliary, and pancreatic origins. It also reacts with Merkel cell carcinoma of skin, frequently with a perinuclear dot-like staining pattern.