Isolated and unexplained dilation of the common bile duct on computed tomography scanscans

Isolated dilation of common bile duct (CBD) with normal sized pancreatic duct and without identifiable stones or mass lesion (unexplained) is frequently encountered by computed tomography/magnetic resonance imaging. We studied the final diagnoses in these patients and tried to elucidate factors that can predict a malignant etiology. This is a retrospective analysis of prospective database from a University based clinical practice (2002- 2008). We included 107 consecutive patients who underwent endoscopic ultrasound (EUS) for evaluation of isolated and unexplained CBD dilation noted on contrast computed tomography scans. EUS examination was performed using a radial echoendoscope followed by a linear echoechoendoscope, if a focal mass lesion was identified. Fine-needle aspirates were assessed immediately by an attending cytopathologist. Main outcome measurements included i) prevalence of neoplasms, CBD stones and chronic pancreatitis and ii) performance characteristics of EUS/EUS-fine needle aspiration (EUS-FNA). A malignant neoplasm was found in 16 patients (14.9%) of the study subjects, all with obstructive jaundice (ObJ). Six patients had CBD stones; three with ObJ and three with abnormal liver function tests. EUS findings suggestive of chronic pancreatitis were identified in 27 patients. EUSFNA had 97.3% accuracy (94.1% in subset with ObJ) with a sensitivity of 81.2% and specificity of 100% for diagnosing malignancy. Presence of ObJ and older patient age were only significant predictors of malignancy in our cohort. Amongst patients with isolated and unexplained dilation of CBD, the risk of malignancy is significantly higher in older patients presenting with ObJ. EUS-FNA can diagnose malignancy in these patients with high accuracy besides identifying other potential etiologies including missed CBD stones and chronic pancreatitis.