Unexpected metastasis of intraductal papillary neoplasm of the bile duct without an invasive component to the brain and lungs:A case report

BACKGROUND Despite an expanding number of studies on intraductal papillary neoplasm of the bile duct(IPNB),distant metastasis remains unexplained especially in cases of carcinoma in situ.In the present study,we report a rare and interesting case of IPNB without invasive components that later metastasized to lungs and brain.CASE SUMMARY A 69-year-old male was referred to our hospital due to suspected cholangiocarcinoma.Laboratory tests on admission reported a mild elevation of alkaline phosphatase,γ-glutamyl transpeptidase,and total bilirubin in serum.Endoscopic retrograde cholangiography revealed a filling defect in the common bile duct(CBD)extending to the left hepatic duct.Peroral cholangioscopy delineated a tumor in the CBD that had a papillary pattern.Multidetector computed tomography and magnetic resonance cholangiopancreatography detected partial blockage ot interlude in the CBD leading to cholestasis without evidence of metastasis.Therefore,a diagnosis of IPNB cT1N0M0 was established.Left hepatectomy with bile duct reconstruction was performed.Pathological examination confirmed an intraepithelial neoplasia pattern without an invasive component and an R0 resection achievement.The patient was monitored carefully by regular examinations.However,at 32 mo after the operation,a 26 mm tumor in the lungs and a 12 mm lesion in the brain were detected following a suspicious elevated CA 19-9 level.Video-assisted thoracoscopic surgery of left upper lobectomy and stereotactic radiotherapy are indicated.In addition to histopathological results,a genomic profiling analysis using whole exome sequencing subsequently confirmed lung metastasis originating from bile duct cancer.CONCLUSION This case highlights the important role of genomic profiling analysis using whole exome sequencing in identifying the origin of metastasis in patients with IPNB.

Whole-exome sequencing for a more accurate diagnosis of intraductal papillary neoplasms of the bile duct

Introduction According to the World Health Organization(WHO,2018),intraductal papillary neoplasms of the bile duct(IPNB)are characterized as polypoid masses in dilated bile ducts;additionally,invasive IPNB occasionally presents with a nodular surface or mass formation[1,2].The IPNB diagnostic criteria are,however,often ambiguous,e.g.whether IPNB is considered a type of cancer and whether it must have mucus production are debatable[3].Therefore,establishing new IPNB diagnostic criteria based on an alternative approach,such as whole-exome sequencing,is required.Here,we present a case of IPNB with atypical features on which we performed a detailed genetic analysis to determine the genetic,morphological,and histological features of IPNB in this case.