Expression of K homology domain containing protein (KOC) in pancreatic cytology with corresponding histology.

To evaluate if immunocytochemical expression of K homology domain containing protein overexpresssed in cancer (KOC) in biliary brushings and fine needle aspiration improves the diagnostic capability of cytology for intraductal papillary mucinous neoplasm (IPMN) and pancreatic ductal adenocarcinoma (PDA). Fourteen PDAs, 15 IPMNs and 7 chronic pancreatitis cases were obtained. The cytology smears and surgical specimens were stained with antibody to KOC (1:500). The intensity (scale 0-3+) and per centage of cells staining were evaluated in pathologic lesions, and diffuse (>75% of cells) staining of 3+ intensity was considered positive. There was 100% specificity for diagnosing PDA. The sensitivity was greater in histology (79%) than cytology (71%). All chronic pancreatitis and IPMN cases, including IPMN with high grade dysplasia, were negative. Benign epithelium adjacent to PDA or IPMN was also negative. This study demonstrated that PDA can be differentiated from IPMN and benign ductal epithelium using KOC expression. This could be useful in cytologic cases where atypical features preclude a definitive diagnosis of malignancy.