Branch-type intraductal papillary neoplasm of the bile duct treated with laparoscopic anatomical resection: a case report

Abstract

Background: Intraductal papillary neoplasm of the bile duct (IPNB) is characterized by an intraluminal, growing papillary tumor covered by neoplastic biliary epithelial cells with a fine fibrovascular core. IPNB was introduced as a precancerous and early neoplastic lesion in the 2010 World Health Organization classification of tumors of the digestive system. IPNB eventually invades the bile duct wall and progresses to invasive cholangiocarcinoma. IPNB resembles intraductal papillary mucinous neoplasm of the pancreas (IPMN), particularly the main pancreatic duct type. IPNB cases, possibly corresponding to branch-type IPMN, have been recently reported, and these cases involved the peribiliary glands significantly and showed gross cystic dilatation. Small branch-type intrahepatic IPNB often mimics simple liver cysts, making the diagnosis of IPNB difficult. Some literature recommended surgical resection for treatment. Laparoscopic resection is a good treatment option for small tumor. We herein present the case of branch-type IPNB that was treated with laparoscopic anatomical liver resection 5 years after being detected.

Case presentation: A 64-year-old woman was undergoing follow-up for primary aldosteronism. In 2012, follow-up computed tomography (CT) incidentally revealed a 7-mm cystic lesion in segment 8 of the liver. From 2012 to 2017, the cystic lesion kept increasing in size, reaching 17 mm. In 2017, CT also revealed a 13-mm mural nodule in the cyst wall. Therefore, the patient was referred to our department for possible malignancy. We suspected a branch-type IPNB; however, the mass was small and diagnosis could not be made without performing biopsy. Accordingly, surgical resection was performed for diagnosis and treatment. Because branch-type IPNB might show horizontal spread through the intrahepatic bile duct, we believed that anatomical resection of the liver was appropriate considering the malignant potential of the lesion. Therefore, laparoscopic anatomical resection of segment 8 of the liver was performed. The resected tumor measured 17 mm and was histologically diagnosed as a high-grade IPNB.

Conclusion: Branch-type IPNBs are rare but can potentially lead to malignant tumors. Surgical resection is the treatment of choice, with laparoscopic anatomical resection being a good treatment option for this small tumor.

Keywords: Intraductal papillary mucinous neoplasm of the pancreas; Intraductal papillary neoplasm of the bile duct; Laparoscopic anatomical resection; Segmentectomy; Surgical margin.

Fig. 1

Computed tomography findings. Computed tomography scans showed a a 7-mm cystic nodule in 2012 (white arrow), b an 11-mm cystic nodule in 2016 (white arrow), and c a 17-mm cystic nodule in 2017 (white arrow) as well as a mural nodule in the wall

Fig. 2

a, b Magnetic resonance imaging findings. c Ultrasonography findings. Magnetic resonance imaging showed slight dilation of the distal bile duct (white arrow). Ultrasound showed a highly echoic papillary nodular area in the cystic lesion

Fig. 3

Anatomical observations and intraoperative findings. a Schema showing anatomy of the liver and the blood vessels. b, c Intraoperative views of the major steps of laparoscopic segmentectomy

Fig. 4

Macroscopic and microscopic findings of resected specimen. a Resected specimen showing a papillary tumor in the cystic wall. b–d Histopathological examination revealed the presence of an intraductal papillary neoplasm of the bile duct on hematoxylin and eosin (H&E) staining. b The papillary tumor cells (black arrow) can be observed in the cystic wall (white arrow) (H&E staining; magnification, × 40). c The tumor was a high-grade (H&E staining; magnification, × 400). d The tumor only located in the cystic wall and did not invade the wall of the adjacent bile duct (H&E staining; magnification, × 400)