Extrahepatic bile duct polyp mimicking biliary parasitic disease

A 70-year-old woman complained of fever and epigastric pain. Her hepatobiliary enzymes were raised. Ultrasonography revealed an isoechoic mass in the left hepatic bile duct ([Fig. 1]). Endoscopic retrograde cholangiography (ERC) disclosed a well-demarcated 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 mucosa was observed by choledochoscopy 2 months postoperatively ([Fig. 6]). The patient was doing well 13 years postoperatively.

Fig. 1 Ultrasonography showing an elliptical isoechoic mass (arrow) in the hilar left hepatic duct.

Fig. 2 Endoscopic retrograde cholangiography (ERC) demonstrating a polypoid defect in the hilar bile duct.

Fig. 3 The polypoid lesion could not be extracted with a basket catheter because it was partly adhered to the lumen of the bile duct.

Fig. 4 The red polyp was extracted from the lumen of the bile duct.

Fig. 5 Photomicrograph of the resected specimen showing a lobular architecture comprising hyperplastic glands. The surface is covered by columnar epithelium.

Fig. 6 Follow-up choledochoscopy. A linear scar surrounded by regenerative mucosa was present at the resection site.

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.

Endoscopy_UCTN_Code_CCL_1AZ_2AC

Competing interests: None

• References

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