Extrahepatic bile duct polyp mimicking biliary parasitic disease

Abstract

A 70-year-old woman complained of fever and epigastric pain. Her hepatobiliary enzymes were raised. Ultrasonography revealed an isoechoicmass in the left hepatic bile duct (● Fig.1). Endoscopic retrograde cholangiography (ERC) disclosed a welldemarcated elliptical filling defect in the left hepatic bile duct (● Fig.2). Endoscopic extraction was attempted (● Fig.3) because of possible erratic parasitism. However, the lesion was focally adhered to the lumen. Laparotomy was performed because of a possible neoplastic lesion, based on the ERC findings. The soft, red polyp was extracted from the lumen of the bile duct (● Fig.4). The polypoid lesion was composed of hyperplastic glands and covered by columnar epithelium (● Fig.5). A linear scar surrounded by regenerative mucosawas observed by choledochoscopy 2 months postoperatively (● Fig.6). The patientwasdoingwell 13yearspostoperatively. Benign neoplasms of the extrahepatic bile duct are uncommon. Benign bile duct tumors are found in 0.1% of all biliary tract surgeries [1]. Bile duct polyps sometimes cause obstructive cholangitis, but they can easily be overlooked because of their low incidence. Moreover, the preoperative images of both bile duct polyps and parasites are similar, which may result in incorrect diagnosis. However, the differential points are as follows: with bile duct parasites, echogenic tubular central lines that represent the digestive tracts of the worm are seen in a nonshadowing mass within the bile duct by ultrasonography [2], and with polyps, on ERC, elliptical repletion defects are unilaterally fixed to the bile duct [3]. The cause of bile duct polyps is unknown. A relationship to mechanical stimuli has been suggested, but the incidence of simultaneous bile duct stones is between 7.7% [4] and 11.6% [5]. The recurrence rate of neoplastic polyps, including adenomas and papillomas, after surgical procedures is 5%–22% [1]. Follow-up is recommended for neoplastic polyps.