Systematic cytological evaluation and immunocytochemistry of minichromosome maintenance protein 2 and p53 significantly improve cytological diagnosis of pancreaticobiliary adenocarcinoma.

Endoscopic retrograde cholangiopancreatography (ERCP) brushing cytology often cannot distinguish adenocarcinoma from reactive epithelial changes. We attempted to improve the diagnostic sensitivity of ERCP using the following methods: systematic cytological evaluation, immunocytochemical examination of minichromosome maintenance proteins (MCM) 2 and p53, and a combination of these methods. ERCP specimens from 53 patients (13 benign and 40 malignant cases) were studied. First, we reclassified the cases into three categories according to the systematic cytological evaluation: negative, suspicious, and positive. Secondly, immunocytochemistry was performed for MCM 2 and p53. The cut-off values were set at 25% labeling index (LI) for MCM 2 and 10% LI for p53, respectively. We evaluated the sensitivity, specificity, and diagnostic accuracy. The sensitivity of the systematic cytological evaluation alone did not improve significantly, compared with the original screening examination (77% vs. 68%). The sensitivity of immunocytochemistry for MCM 2 and p53 was 90% (P < 0.05) and 68%, respectively. Applying only the suspicious or positive categories, the sensitivity improved significantly to 93% for the combination of systematic cytological evaluation and immunocytochemistry for MCM 2 and p53 (P < 0.01). In conclusion, the combination of morphology and immunocytochemistry for MCM 2 and p53 may help to overcome the diagnostic cytological difficulties of pancreaticobiliary adenocarcinoma.