The evaluation of MSX2 mRNA expression level in biliary brush cytological specimens.

BACKGROUND To distinguish cholangiocarcinoma from inflammatory disease remains difficult when stricture is present in the bile duct. Endoscopic brushing cytology is a convenient method for stricture in the bile duct, however, the diagnostic sensitivity of this method for malignancy is reported to be low (<60%). Msh homeobox 2 is frequently expressed in carcinoma cells of epithelial origin but not in normal tissues. AIM To assess whether MSX2 expression level in brushing samples allows differentiation of malignant from benign bile duct stricture. PATIENTS AND METHODS Cytological brushing specimens were obtained from strictures of the bile duct during endoscopic retrograde cholangiopancreaticography (ERCP) in 71 patients. The brushing fluid was subjected to cytological diagnosis and RNA extraction. The expression level of MSX2 was evaluated by one-step real-time RT-PCR. RESULTS MSX2 expression levels were significantly higher in malignant than in benign bile duct stricture (p=0.004). The sensitivity and specificity for cholangiocarcinoma of cytology and MSX2 expression in strictures of the bile duct were: 55.3% and 100%, and 72.3% and 58.3%, respectively. CONCLUSION The sensitivity of MSX2 expression level for cholangiocarcinoma was much higher than that of cytology. This suggests that the evaluation of MSX2 level in ERCP brushing samples would be a useful tool to distinguish malignant from benign bile duct stricture.