SOX9: a useful marker for pancreatic ductal lineage of pancreatic neoplasms.

Previous studies showed that SOX9 plays a critical role in pancreatic ductal development. The aim of this study was to evaluate SOX9 as a marker for pancreatic ductal lineage. SOX9 expression was evaluated by immunohistochemistry in 146 benign pancreas (BP), 136 pancreatic ductal adenocarcinomas, 47 pancreatic intraepithelial neoplasia (PanIN), 21 intraductal papillary mucinous neoplasms (IPMNs), 14 mucinous cystic neoplasms, 10 serous cystadenomas, 39 pancreatic neuroendocrine tumors, 9 acinar cell carcinomas, and 23 solid pseudopapillary neoplasms. Nuclear expression of SOX9 was detected in the centroacinar cells and ductal cells, but not in acinar or endocrine cells in 100% BP. Focal or diffuse SOX9 expression was detected in 100% PanINs, 100% IPMNs, 100% mucinous cystic neoplasms, 100% serous cystadenomas, 89.0% pancreatic ductal adenocarcinomas, 2.6% pancreatic neuroendocrine tumors, 11.1% acinar cell carcinomas, and 0% solid pseudopapillary neoplasms. SOX9 expression was lower in PanIN2 and PanIN3 than in PanIN1 lesions (P < .01). Compared with BP, IPMN had lower SOX9 expression (P < .05). No correlation between SOX9 expression and other clinicopathologic parameters was identified. Our study showed that SOX9 is expressed in centroacinar and ductal epithelial cells of BP and is a useful marker for pancreatic ductal lineage of pancreatic neoplasms.