OBJECTIVETo study the cytologic features of pancreatobiliary tumors in endoscopic retrograde cholangiopancreatography (ERCP)-guided brushing preparations and to evaluate the usefulness of cytology in the diagnosis of pancreatobiliary malignancy.

METHODSA retrospective analysis of 212 cases of ERCP-guided brush cytology smears performed during the period from January, 2004 to December, 2006. The cytologic diagnosis was confirmed either by the histologic diagnosis or the strict clinical criteria.

RESULTSTwo of the cases studied were unsatisfactory for diagnosis, with no epithelial cells identified. One hundred and thirty-seven smears were diagnosed as "negative", 45 of which subsequently confirmed to be malignant (negative predictive value = 60.2%). Six of the 11 cases with "low-grade atypia" were proven to be malignant (positive predictive value = 54.5%), as compared to 19 of 23 cases of "high-grade atypia" (positive predictive value = 86.4%). All of the 41 cases with cytologic diagnosis of "malignancy" were confirmed to be malignant (positive predictive value = 100%). The cytologic features of malignancy in ERCP-guided brushing preparations included overlapping nuclei, anisonucleosis, coarse chromatin pattern, poor cellular cohesion, tumor diathesis, prominent nucleoli and atypical mitotic figures.

CONCLUSIONSThe accuracy of ERCP-guided brush cytology relies on good specimen preparation and application of morphologic criteria. Grading of cytologic atypia is of clinical significance. A "negative" or "low-grade atypia" cytologic diagnosis requires further diagnostic workup to rule out the possibility of underlying malignancy, while a "high-grade atypia" or "malignant" diagnosis is relatively specific in guiding subsequent management of suspected pancreatobiliary malignancy.