Intraductal papillary neoplasms of the bile duct: stepwise progression to carcinoma involves common molecular pathways

Characterization of Intraductal Papillary Neoplasm of the Bile Duct with Respect to the Histopathologic Similarities to Pancreatic Intraductal Papillary Mucinous Neoplasm

Intraductal papillary neoplasms of the bile duct (IPNBs) are known to show various pathologic features and biological behaviors. Recently, two categories of IPNBs have been proposed based on their histologic similarities to pancreatic intraductal papillary mucinous neoplasms (IPMNs): type 1 IPNBs, which share many features with IPMNs; and type 2 IPNBs, which are variably different from IPMNs. The four IPNB subtypes were re-evaluated with respect to these two categories. Intestinal IPNBs showing a predominantly villous growth may correspond to type 1, while those showing papillay-tubular or papillay-villous growth correspond to type 2. Regarding gastric IPNB, those with regular foveolar structures with varying numbers of pyloric glands may correspond to type 1, while those with papillary-foveolar structures with gastric immunophenotypes and complicated structures may correspond to type 2. Pancreatobiliary IPNBs that show fine ramifying branching may be categorized as type 1, while others containing many complicated structures may be categorized as type 2. Oncocytic type, which displays solid growth or irregular papillary structures, may correspond to type 2, while papillary configurations with pseudostratified oncocytic lining cells correspond to type 1. Generally, type 1 IPNBs of any subtype develop in the intrahepatic bile ducts, while type 2 IPNBs develop in the extrahepatic bile duct. These findings suggest that IPNBs arising in the intrahepatic ducts are biliary counterparts of IPMNs, while those arising in the extrahepatic ducts display differences from prototypical IPMNs. The recognition of these two categories of IPNBs with reference to IPMNs and their anatomical location along the biliary tree may deepen our understanding of IPNBs.

Genetically engineered animal models of biliary tract cancers

PURPOSE OF REVIEW

Biliary tract cancers which include intrahepatic and extrahepatic cholangiocarcinomas and gallbladder cancer, are characterized by poor outcome. Therefore, identifying the molecular mechanisms of the disease has become a priority. However, such identification has to cope with extreme heterogeneity of the disease, which results from the variable anatomical location, the numerous cell types of origin and the high number of known genetic alterations.

RECENT FINDINGS

Animal models can develop invasive and metastatic tumours that recapitulate as faithfully as possible the molecular features of the human tumours. To generate animal models of cholangiocarcinoma, investigators resorted to the administration of carcinogens, induction of cholestasis, grafting of tumour cells and induction of genetic modifications.

SUMMARY

Here, we summarize the currently available genetically engineered animal models, and focus on mice and zebrafish. The experimental strategies that were selected to induce cholangiocarcinoma in a time-controlled and cell-type-specific manner are critically examined. We discuss their strengths and limitations while considering their relevance to human pathophysiology.

Cystic intraductal papillary neoplasms with infiltrating carcinoma of the intrahepatic bile duct: A case report

INTRODUCTION

Intraductal papillary neoplasms of the bile duct (IPNB) is a kind of rare disorder with low incidence but high misdiagnosis due to untypical symptoms and non-specific laboratory indicators. Herein, we report a case of cystic type IPNB with infiltrating carcinoma of the intrahepatic bile duct presented as a single giant cystic mass of the liver.

PATIENT CONCERNS

A 51-year-old woman was admitted due to right upper abdominal discomfort for 10 months. Physical examination indicated no specific finding. Laboratory tests showed that serum total bilirubin and carcinoembryonic antigen level was mildly elevated. Ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) of abdomen indicated a giant lobulated cystic lesion involving the left, right and the caudate lobes of liver. There were multiple small nodules of different sizes with papillary or coral reef-like pattern protruding into the cystic lumen from the inner wall.

DIAGNOSIS

The patient was diagnosed as malignant tumors of intrahepatic bile duct.

INTERVENTIONS

She received radical resection of the lesion by hepatectomy.

OUTCOMES

The postoperative pathological examination revealed an IPNB with infiltrating carcinoma of the intrahepatic bile duct. This patient had an uneventful postoperative recovery and was discharged on day 21 post-surgery. Until 35 months after surgery, there is no recurrence or metastasis.

CONCLUSION

The CT and MRI can show certain morphologic features including the segmental cystic dilatation of intrahepatic bile ducts and the pathological details of papillary tumors inside the lesion. Cystic IPNB with infiltrating carcinoma of the intrahepatic bile duct can be treated with surgery.

Precursors to Cholangiocarcinoma

Cancers of the biliary tract include intra- and extrahepatic cholangiocarcinomas and gallbladder cancer. Biliary tract cancers are diseases with unfavorable prognoses. In recent years, several lesions have been described as precursors that precede biliary cancers. They include flat and microscopic lesions known as biliary intraepithelial neoplasia, macroscopic and tumor-forming intraductal papillary biliary neoplasia, intraductal tubular neoplasia, and mucinous cystic neoplasm of the bile duct. These conditions are rarely diagnosed, while their natural history and progression to cancer have yet to be adequately characterized. This review examines the epidemiology, pathology, molecular biology, diagnosis, and therapy of these various precursors. Further research is required if we are to better understand this evolving field and improve the prevention and early detection of bile duct cancer.

Targeted next-generation sequencing identifies distinct clinicopathologic and molecular entities of intraductal papillary neoplasms of the bile duct

Intraductal papillary neoplasm of the bile duct (IPNB) is a mass-forming neoplasm in the bile duct considered to be the biliary counterpart of pancreatic intraductal papillary mucinous neoplasm (IPMN). By its cell lineage, IPNB can be classified into gastric, intestinal, pancreatobiliary, and oncocytic types. Recently, a group of Japanese and Korean pathologists proposed that IPNB be classified into two types, with type 1, being the histological counterpart of IPMN and type 2, having a more complex histological architecture. We used targeted next-generation sequencing to study the molecular change of 37 IPNBs and identified frequent mutations of KRAS (49%), GNAS (32%), RNF43 (24%), APC (24%), TP53 (24%), and CTNNB1 (11%) in IPNBs. Intestinal-type IPNB was associated with KRAS, GNAS, and RNF43 mutations. Japan-Korea consensus type 1 was associated with KRAS and GNAS mutations. All four IPNBs with CTNNB1 mutations were of pancreatobiliary type and located in the extrahepatic bile duct. A hierarchical analysis identified three distinct groups within IPNB: group 1 was Japan-Korea consensus type 1 tumors with macroscopic mucin, old age, and frequent KRAS, GNAS, and RNF43 mutations. Group 2 was Japan-Korea consensus type 2 with intestinal differentiation and frequent KRAS mutation but rare GNAS mutation, MUC2 expression, and macroscopic mucin. Group 3 was characterized by CTNNB1 mutation, extrahepatic location, lack of expression of intestinal markers, Japan-Korea consensus type 2, and lack of mutations in KRAS, APC, RNF43, and GNAS. Our results indicated that IPNB is a heterogeneous disease and that the activation of Ras-mitogen-activated protein kinase (MAPK), Wnt/β-catenin, and G-protein-coupled receptor (GPCR)-cAMP signaling is the main oncogenic mechanism of IPNB.

Recurrent Mutations in APC and CTNNB1 and Activated Wnt/β-catenin Signaling in Intraductal Papillary Neoplasms of the Bile Duct: A Whole Exome Sequencing Study

This study aimed to elucidate the genetic landscape of biliary papillary neoplasms. Of 28 cases examined, 7 underwent whole exome sequencing, while the remaining 21 were used for validation studies with targeted sequencing. In the whole exome sequencing study, 4/7 cases had mutations in either APC or CTNNB1, both of which belong to the Wnt/β-catenin pathway. Somatic mutations were also identified in genes involved in RAS signaling (KRAS, BRAF), a cell cycle regulator (CDC27), histone methyltransferase (KMT2C, KMT2D), and DNA mismatch repair (MSH3, MSH6, PMS1). Combined with discovery and validation cohorts, mutations in APC or CTNNB1 were observed in 6/28 subjects (21%) and were mutually exclusive. When the cases were classified into intraductal papillary neoplasms of the bile duct (IPNBs, n=14) and papillary cholangiocarcinomas (n=14) based on the recently proposed classification criteria, mutations in APC and CTNNB1 appeared to be entirely restricted to IPNBs with 6/14 cases (43%) harboring mutations in either gene. These genetic alterations were detected across the 3 nonintestinal histologic types. In immunohistochemistry, the aberrant cytoplasmic and/or nuclear expression of β-catenin was found in not only 5/6 IPNBs with APC or CTNNB1 mutations, but also 6/8 cases with wild-type APC and CTNNB1 (total 79%). In addition, APC and CTNNB1 alterations were exceptional in nonpapillary cholangiocarcinomas (n=29) with a single case harboring CTNNB1 mutation (3%). This study demonstrated recurrent mutations in APC and CTNNB1 in nonintestinal-type IPNBs, suggesting that activation of the Wnt/β-catenin signaling pathway is relevant to the development and progression of IPNBs.

Outcome Determining Factors of Intraductal Papillary Neoplasm of the Biliary Tract (IPNB)-a Single Center Survey and Analysis of Current Literature

PURPOSE

Intraductal papillary neoplasms of the biliary tract (IPNB) are rare tumors originating from the bile duct epithelium. Metastatic disease of IPNB is extremely rare and only reported in a small number of cases worldwide. Due to this limitation in number, the treatment of IPNB mainly relies on retrospective case series.

PATIENTS AND METHODS

We reported three cases of IPNB, one benign, one carcinoma with lymph node metastasis, and one case with histologically proven metachronous pulmonary metastasis. We correlated our findings with the existing data found in the literature. All patients underwent hemihepatectomy and complete tumor resection was achieved.

RESULTS

Diagnosis of IPNB can be challenging due to varying presentation. The treatment of choice is surgical oncological resection in an early tumor stage. Long-term outcome highly depends on the underlying grade of dysplasia, multiplicity, and tumor-free margins. Aggressive tumor invasion is reported in up to 72% of cases in IPNB. Furthermore, the recurrence rate of IPNB is high with up to 22%. Further factors associated with an impaired survival are incomplete resection, lymph node involvement, and MUC1 expression.

CONCLUSION

High potential for dysplasia and proof of invasive carcinoma upon diagnosis are hallmarks of IPNB. Metastatic disease in IPNB is reported only in small numbers. IPNB is an aggressive tumor entity with impaired long-term outcomes. A drawback for interpretation of current data is the fact that they rely on case series and reports and are not validated through more powerful randomized multicentric trials.

Anatomical, histomorphological and molecular classification of cholangiocarcinoma

Cholangiocarcinoma constitutes a heterogeneous group of malignancies that can emerge at any point of the biliary tree. Cholangiocarcinoma is classified into intrahepatic, perihilar and distal based on its anatomical location. Histologically, conventional perihilar/distal cholangiocarcinomas are mucin-producing adenocarcinomas or papillary tumours; intrahepatic cholangiocarcinomas are more heterogeneous and can be sub-classified according to the level or size of the displayed bile duct. Cholangiocarcinoma develops through multistep carcinogenesis and is preceded by dysplastic and in situ lesions. Definition and clinical significance of precursor lesions, including biliary intraepithelial neoplasia, intraductal papillary neoplasms of the bile duct, intraductal tubulopapillary neoplasms and mucinous cystic neoplasm, are discussed in this review. A main challenge in diagnosing cholangiocarcinoma is the fact that tumour tissue for histological examination is difficult to obtain. Thus, a major clinical obstacle is the establishment of the correct diagnosis at a tumour stage that is amenable to surgery which still represents the only curable therapeutic option. Current standards, methodology and criteria for diagnosis are discussed. Cholangiocarcinoma represents a heterogeneous tumour with regard to molecular alterations. In intrahepatic subtype, mainly two distinctive morpho-molecular groups can currently be discriminated. Large-duct type intrahepatic cholangiocarcinoma shows a high mutation frequency of oncogenes and tumour suppressor genes, such as KRAS and TP53 while Isocitrate Dehydrogenase 1/2 mutations and Fibroblast Growth Factor Receptor 2-fusions are typically seen in small-duct type tumours. It is most important to ensure the separation of the given anatomical subtypes and to search for distinct subgroups within the subtypes on a molecular and morphological basis.

Intraductal papillary neoplasm of the bile duct: Assessment of invasive carcinoma and long-term outcomes using MRI

BACKGROUND & AIMS

Imaging characteristics for discriminating the malignant potential of intraductal papillary neoplasm of the bile duct (IPNB) still remain unclear. This study aimed to define the magnetic resonance (MR) imaging findings that help to differentiate IPNB with an associated invasive carcinoma from IPNB with intraepithelial neoplasia and to investigate their significance with respect to long-term outcomes in patients with surgically resected IPNB.

METHODS

This retrospective study included 120 patients with surgically resected IPNB who underwent preoperative MR imaging with MR cholangiography before surgery from January 2008 and December 2017 in two tertiary referral centers. Clinical and MR imaging features of IPNB with intraepithelial neoplasia (n = 34) and IPNB with an associated invasive carcinoma (n = 86) were compared. Regarding significant features for discriminating IPNB with or without an associated invasive carcinoma, recurrence-free survival (RFS) rates were evaluated.

RESULTS

Significant MR imaging findings for differentiating IPNB with an associated invasive carcinoma from IPNB with intraepithelial neoplasia were intraductal visible mass, tumor size ≥2.5 cm, multiplicity of the tumor, bile duct wall thickening, and adjacent organ invasion (all p ≤0.002). The 1-, 3-, and 5-year RFS rates for surgically resected IPNB were 93.8%, 79.1%, and 70.0%, respectively. RFS rates were significantly lower in patients with each significant MR imaging finding of IPNB with an associated invasive carcinoma than in those without significant MR imaging findings (all p ≤0.039).

CONCLUSIONS

MR imaging with MR cholangiography may be helpful in differentiating IPNB with an associated invasive carcinoma from IPNB with intraepithelial neoplasia. Significant MR imaging findings of IPNB with an associated invasive carcinoma have a negative impact on RFS.

LAY SUMMARY

Significant magnetic resonance imaging findings that differentiated between an intraductal papillary neoplasm of the bile duct (IPNB) with an associated invasive carcinoma and an IPNB with intraepithelial neoplasia were intraductal visible mass, tumor size ≥2.5 cm, multiplicity of the tumor, bile duct wall thickening, and adjacent organ invasion. Significant magnetic resonance imaging findings of invasive IPNB have a negative impact on recurrence-free survival.

Molecular Pathogenesis of Cholangiocarcinoma

BACKGROUND

Cholangiocarcinomas are a heterogeneous group of malignancies arising from a number of cells of origin along the biliary tree. Although most cases in Western countries are sporadic, large population-based studies have identified a number of risk factors. This review summarises the evidence behind reported risk factors and current understanding of the molecular pathogenesis of cholangiocarcinoma, with a focus on inflammation and cholestasis as the driving forces in cholangiocarcinoma development.

RISK FACTORS FOR CHOLANGIOCARCINOGENESIS

Cholestatic liver diseases (e.g. primary sclerosing cholangitis and fibropolycystic liver diseases), liver cirrhosis, and biliary stone disease all increase the risk of cholangiocarcinoma. Certain bacterial, viral or parasitic infections such as hepatitis B and C and liver flukes also increase cholangiocarcinoma risk. Other risk factors include inflammatory disorders (such as inflammatory bowel disease and chronic pancreatitis), toxins (e.g. alcohol and tobacco), metabolic conditions (diabetes, obesity and non-alcoholic fatty liver disease) and a number of genetic disorders.

MOLECULAR PATHOGENESIS OF CHOLANGIOCARCINOMA

Regardless of aetiology, most risk factors cause chronic inflammation or cholestasis. Chronic inflammation leads to increased exposure of cholangiocytes to the inflammatory mediators interleukin-6, Tumour Necrosis Factor-ɑ, Cyclo-oxygenase-2 and Wnt, resulting in progressive mutations in tumour suppressor genes, proto-oncogenes and DNA mismatch-repair genes. Accumulating bile acids from cholestasis lead to reduced pH, increased apoptosis and activation of ERK1/2, Akt and NF-κB pathways that encourage cell proliferation, migration and survival. Other mediators upregulated in cholangiocarcinoma include Transforming Growth Factor-β, Vascular Endothelial Growth Factor, Hepatocyte Growth Factor and several microRNAs. Increased expression of the cell surface receptor c-Met, the glucose transporter GLUT-1 and the sodium iodide symporter lead to tumour growth, angiogenesis and cell migration. Stromal changes are also observed, resulting in alterations to the extracellular matrix composition and recruitment of fibroblasts and macrophages that create a microenvironment promoting cell survival, invasion and metastasis.

CONCLUSION

Regardless of aetiology, most risk factors for cholangiocarcinoma cause chronic inflammation and/or cholestasis, leading to the activation of common intracellular pathways that result in reactive cell proliferation, genetic/epigenetic mutations and cholangiocarcinogenesis. An understanding of the molecular pathogenesis of cholangiocarcinoma is vital when developing new diagnostic biomarkers and targeted therapies for this disease.

Uncommon Intraluminal Tumors of the Gallbladder and Biliary Tract: Spectrum of Imaging Appearances

Intraluminal pathologic conditions of the bile ducts and gallbladder are common, most frequently consisting of calculi and adenocarcinoma. In recent years, intraductal papillary neoplasm of the bile ducts (IPN-B), which is analogous to intraductal papillary mucinous neoplasm of the pancreas, has been recognized as a distinct pathologic entity and a precursor lesion to adenocarcinoma of the bile ducts. Intraductal tubulopapillary neoplasm (ITPN) of the bile duct was subsequently described as a distinct pathologic entity. With increased awareness and advances in imaging techniques, these lesions are diagnosed with increased frequency at preoperative imaging. A similar neoplasm in the gallbladder is referred to as intracholecystic papillary neoplasm. These lesions are often diagnosed at a preinvasive stage and have a better prognosis than invasive cholangiocarcinoma when treated with curative resection, underscoring the importance of an accurate imaging diagnosis. The most common causes of polypoid lesions of the gallbladder are cholesterol polyps and adenomyomatosis. These lesions need to be differentiated from the less common but clinically important adenocarcinoma of the gallbladder. Imaging is crucial to identify polyps that are at high risk for malignancy so that the appropriate management choice between imaging follow-up and cholecystectomy can be made by the treating physicians. Other less common gallbladder tumors, such as gallbladder adenomas, lymphoma, and metastases to the gallbladder, can manifest as intraluminal tumors; and awareness of these lesions is also important. In this article, the recent literature is reviewed; and the imaging appearances, histopathologic findings, and management of uncommon intraluminal tumors of the bile ducts and gallbladder and their mimics are discussed. ^©RSNA, 2019.

CT imaging comparison between intraductal papillary neoplasms of the bile duct and papillary cholangiocarcinomas

OBJECTIVES

To identify imaging features that assist in discriminating intraductal papillary neoplasms of the bile duct (IPNBs) from papillary cholangiocarcinomas (PCCs).

METHODS

This study was approved by the institutional review board. Using the recently proposed histological diagnostic criteria for biliary papillary neoplasms, IPNBs and PCCs were selected from 537 biliary neoplasms consecutively resected in a 12.5-year period. Clinical and imaging features were compared between the two groups.

RESULTS

The histology review identified 19 IPNBs and 48 PCCs, representing an estimated prevalence of IPNBs among biliary neoplasms of 4%. Approximately one half of IPNBs were incidentally found on imaging conducted for other purposes. In terms of tumor location, 15/19 IPNBs (79%) developed in intrahepatic bile ducts, and 41/48 PCCs (85%) in the distal bile duct. Cystic appearance was highly suggestive for IPNBs (p < 0.001). Using these two parameters, 78% of papillary bile duct neoplasms could be classified into IPNBs or PCCs. Other imaging findings favoring IPNBs included frond-like mural nodule, downstream bile duct dilatation, and the lack of abnormal enhancement in the adjacent bile duct. Interestingly, two patients with non-invasive or microinvasive IPNB had undergone abdominal imaging studies > 3 years before, and a retrospective review of the previous images identified small nodular or cystic lesions, suggesting a less progressive nature of IPNBs than currently thought.

CONCLUSIONS

Imaging findings useful for discriminating IPNBs from PCCs appear to be tumor location, shape of tumor, appearance of mural nodules, duct dilatation at unaffected duct, and abnormal enhancement of the adjacent bile duct.

KEY POINTS

• Intrahepatic location and cystic dilatation of the affected bile duct are the strong discriminators between IPNBs and PCCs. • The shape of the mural nodule and appearance of the neighboring bile duct are helpful for distinguishing IPNBs and PCCs. • The less aggressive behavior of IPNBs compared with PCCs may facilitate less invasive management in patients with IPNB.

A huge intraductal papillary neoplasm of the bile duct treated by right trisectionectomy after right portal vein embolization

Intraductal papillary neoplasm of the bile duct (IPNB) is a rare variant of bile duct tumors characterized by papillary growth within the bile duct lumen and recognized precursor of invasive carcinoma. IPNB was detected incidentally in a 60-year-old woman during check up. Radiologic images revealed a huge cystic mass with papillary projection and markedly dilated bile ducts. Biopsies revealed high-grade IPNB. Cholangioscopy detected a connection between the right posterior bile duct and cyst lumen with epithelial dysplasia of the bile duct. Right posterior sectional duct opened in the left hepatic duct. Consequently, right trisectionectomy and extrahepatic bile duct resection were conducted. Histological studies revealed intraductal papillary neoplasm with high-grade intraepithelial neoplasia (carcinoma in situ). IPNB patients without distant metastases are candidates for surgery and complete resection should be conducted to achieve long-term survival.

Cholangiocarcinoma

This article focuses on cholangiocarcinoma, both intrahepatic and extrahepatic. The various classification schemes based on anatomic location, macroscopic growth pattern, microscopic features, and cell of origin are outlined. The clinicopathologic, immunohistochemical and molecular differences between intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma, as well as differences in the 2 subtypes of intrahepatic cholangiocarcinoma, are discussed. Finally, precursor lesions, prognosis, treatment, and promising new potential targeted therapies are reviewed.

Intraductal papillary neoplasia of the bile duct with malignancy: a differentiated entity of cholangiocarcinoma with a better prognosis. A review of three new cases

INTRODUCTION

Intraductal papillary neoplasms of the bile duct have been recognized as a differentiated entity to other biliary tumors since 2001. They are characterized by intraductal growth, with or without mucus production, and have malignant potential, although they have a better prognosis than other types of cholangiocarcinoma.

CASE REPORTS

From January 2010 to August 2015, we included three patients with a confirmed diagnosis of bile duct intraductal papillary neoplasia with malignancy that were treated at our center. Two cases were male and one female with a mean age of 67.3 years. All three patients presented malignancy at the time of diagnosis. One patient was asymptomatic and the diagnosis was reported in the hepatectomy specimen after a liver transplant due to autoimmune hepatitis. The other two patients presented with cholestasis and acute cholangitis and the diagnosis was made based on imaging tests (computed tomography [CT] and magnetic resonance imaging [MRI]) and endoscopic retrograde cholangiopancreatography (ERCP) with brushing and a biopsy. The treatment in both cases was surgical with a left hepatectomy, and resection of the left bile duct and segment I. They did not receive adjuvant treatment. None of the cases had recurrence of the disease.

DISCUSSION

Malignant intraductal papillary neoplasias of the biliary tract represent a different entity of cholangiocarcinoma with a better prognosis. Its diagnosis is based on imaging tests and histology by ERCP. The treatment is surgical, achieving a high rate of success with a low relapse rate.

The curious case of Gαs gain-of-function in neoplasia

BACKGROUND

Mutations activating the α subunit of heterotrimeric Gs protein are associated with a number of highly specific pathological molecular phenotypes. One of the best characterized is the McCune Albright syndrome. The disease presents with an increased incidence of neoplasias in specific tissues.

MAIN BODY

A similar repertoire of neoplasms can develop whether mutations occur spontaneously in somatic tissues during fetal development or after birth. Glands are the most "permissive" tissues, recently found to include the entire gastrointestinal tract. High frequency of activating Gαs mutations is associated with precise diagnoses (e.g., IPMN, Pyloric gland adenoma, pituitary toxic adenoma). Typically, most neoplastic lesions, from thyroid to pancreas, remain well differentiated but may be a precursor to aggressive cancer.

CONCLUSIONS

Here we propose the possibility that gain-of-function mutations of Gαs interfere with signals in the microenvironment of permissive tissues and lead to a transversal neoplastic phenotype.

A statement by the Japan-Korea expert pathologists for future clinicopathological and molecular analyses toward consensus building of intraductal papillary neoplasm of the bile duct through several opinions at the present stage

Intraductal papillary neoplasm of bile duct (IPNB) was described as a preinvasive neoplastic lesion of the biliary tract in the 2010 World Health Organization (WHO) classification. Although a number of studies have since been conducted on IPNBs, controversy remains, particularly regarding the standardization of its definition. Meetings by Japanese and Korean expert pathologists were held twice to resolve the pathological diagnostic aspects of IPNB. Through round-table discussions and histological reviews, we reached the common understanding that IPNBs diagnosed according to the criteria of WHO 2010 are characterized by intraductal predominant papillary or villous biliary neoplasms covering delicate fibrovascular stalks and are classified into two types pathologically. One type (type 1 IPNB) is histologically similar to intraductal papillary mucinous neoplasms of pancreas, and typically develops in the intrahepatic bile ducts, while the other (type 2 IPNB) has a more complex histological architecture with irregular papillary branching or with foci of solid-tubular components and typically involves the extrahepatic bile ducts. This report states the diagnostic pathologic features of IPNB proposed by WHO 2010. Since currently, the concept of IPNB is still confusing, the proposed diagnostic pathologic features stated here will be of use for future clinicopathological and molecular analyses toward consensus building of IPNB.

Morphological classification of intraductal papillary neoplasm of the bile duct

OBJECTIVES

To investigate the morphological classification of intraductal papillary neoplasm of the bile duct (IPNB), as well as morphological differences between IPNB without mucin secretion (IPNB-NM) and IPNB with mucin secretion (IPMN-B).

METHODS

Eighty-one patients with IPNB were retrospectively analysed. Imaging examinations included computed tomography (CT), magnetic resonance imaging (MRI), gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI and positron emission tomography-computed tomography (PET-CT). According to the morphology of tumours and extent of bile duct dilations, IPNB was classified into seven types: I, upstream-ductectatic type; II, typical type; III, superficial-spreading type; IV, no-mass-forming type; V, intrahepatic-cystic type; VI, extrahepatic-cystic type; and VII, infiltrating type.

RESULTS

Thirteen IPNB-NM patients comprised type I (11 cases), type II (1 case) and type VII (1 case); 68 IPMN-B patients comprised type I (2 cases), type II (30 cases), type III (6 cases), type IV (11 cases), type V (13 cases), type VI (2 cases) and type VII (4 cases). Bile duct dilations were more severe in IPMN-B than in IPNB-NM. PET-CT and Gd-EOB-DTPA-enhanced MRI clearly demonstrated the extension of infiltrating IPNB.

CONCLUSIONS

IPNB can be classified into seven morphological types. IPNB-NM and IPMN-B have different morphological features.

KEY POINTS

• IPNB can be classified into seven morphological types. • IPNB-NM and IPMN-B have different morphological features. • Enhanced CT and MRI can display different types of IPNB. • Morphological classification of IPNB facilitates management of the disease.

KRAS mutation and immunohistochemical profile in intraductal papillary neoplasm of the intrahepatic bile ducts

Intraductal papillary neoplasm of bile duct (IPNB) is characterized by a spectrum of diseases ranging from low-grade intraepithelial neoplasia to invasive carcinoma. In the present study, we aimed to investigate immunophenotypic features and KRAS mutations in relation to pathological subtypes and grades in Chinese patients with IPNBs. A total of 46 patients with IPNBs and 11 invasive adenocarcinomas arising in IPNBs (invasive IPNBs) were enrolled and clinicopathological data were analyzed. It was found that CK7 was expressed in 42 of the 46 neoplastic lesions. HepPar1 was expressed in 11 of the 46 noninvasive IPNBs, but not in invasive IPNBs. Additionally, CK19 was frequently expressed in both noninvasive IPNBs and invasive IPNBs. The intestinal-type IPNBs had a significantly higher percentage of MUC2 expression relative to the pancreaticobiliary (P=0.015) and gastric-type IPNBs (P<0.001). High-grade IPNBs and invasive IPNBs showed increased expression of cyclin D1, Ki-67, p53, mCEA, and CA19-9. The rate of KRAS mutation was significantly higher in high-grade IPNBs (P=0.001) and invasive IPNBs (P=0.006) than that in low- to intermediate-grade IPNBs. Additionally, KRAS mutation was significantly associated with tumor size, and Ki-67 expression. In conclusion, the expression of cyclin D, Ki-67, p53, mCEA and CA19-9 and KRAS mutation status are significantly correlated with histological grades of IPNBs.

[Upper abdominal pain and febrile episodes in a 44-year-old Filipino woman]

A 44-year-old Filipino woman presented with abdominal pain and fever. Clinical examination and blood tests revealed no pathological results; however, (cross-sectional) imaging showed saccular cystic bile duct dilatation in the right liver with solid intraductal masses. Due to the clinical presentation the patient was admitted for surgical intervention with the diagnosis of Caroli disease. During the surgical procedure histopathology showed an intraductal papillary neoplasm of the bile duct (IPNB). The planned segmentetomy was extended to hemihepatectomy. IPNB is a rare entity of premalignant lesions of the bile duct system first recognized by the World Health Organization in 2010.

Primary malignant tumours in the non-cirrhotic liver

Intrahepatic chlangiocarcinomas (CCs), the second most common primary malignant liver tumours, usually occur in non-cirrhotic liver, and can be classified into three types based on gross morphology: mass-forming; periductal infiltrating; and intraductal growing. Among them, mass-forming intrahepatic CCs are the most common type and characterized by homogeneous mass with an irregular but well-defined margin with peripheral enhancement on late arterial phase and delayed enhancement in central portion of tumours corresponding to the fibrous stroma. Several imaging features such as enhancement pattern and degree of diffusion restriction have been suggested as prognostic markers for mass-forming CCs. Hepatocellular carcinomas (HCCs) are the most common primary malignant liver tumors, and usually arise from the cirrhotic liver. However, approximately 20% of HCCs involve the non-cirrhotic liver (hereafter, non-cirrhotic HCC), and non-cirrhotic HCCs are often detected at an advanced stage due to the lack of surveillance for patients with non-cirrhotic liver. Other primary malignant liver tumours other than CCs and HCCs including angiosarcoma, undifferentiated embryonal sarcoma are quite rare, and imaging diagnosis is often difficult. This review offers a brief overview of epidemiology, risk factors and imaging features of primary malignant tumours in non-cirrhotic liver. Understanding of radiologic appearance and predisposing clinical features as well as differentials of primary malignant tumour in non-cirrhotic liver can be helpful for radiologists to adequately assess these tumours, and subsequently to make optimal management plan.

Transforming growth factor-β in liver cancer stem cells and regeneration

Cancer stem cells have established mechanisms that contribute to tumor heterogeneity as well as resistance to therapy. Over 40% of hepatocellular carcinomas (HCCs) are considered to be clonal and arise from a stem-like/cancer stem cell. Moreover, HCC is the second leading cause of cancer death worldwide, and an improved understanding of cancer stem cells and targeting these in this cancer are urgently needed. Multiple studies have revealed etiological patterns and multiple genes/pathways signifying initiation and progression of HCC; however, unlike the transforming growth factor β (TGF-β) pathway, loss of p53 and/or activation of β-catenin do not spontaneously drive HCC in animal models. Despite many advances in cancer genetics that include identifying the dominant role of TGF-β signaling in gastrointestinal cancers, we have not reached an integrated view of genetic mutations, copy number changes, driver pathways, and animal models that support effective targeted therapies for these common and lethal cancers. Moreover, pathways involved in stem cell transformation into gastrointestinal cancers remain largely undefined. Identifying the key mechanisms and developing models that reflect the human disease can lead to effective new treatment strategies. In this review, we dissect the evidence obtained from mouse and human liver regeneration, and mouse genetics, to provide insight into the role of TGF-β in regulating the cancer stem cell niche. (Hepatology Communications 2017;1:477-493).

Clinicopathological features of intraductal papillary neoplasms of the bile duct: a comparison with intraductal papillary mucinous neoplasm of the pancreas with reference to subtypes

Intraductal papillary epithelial neoplasms of the pancreatobiliary system (intraductal papillary neoplasm of the bile duct (IPNB) and intraductal papillary mucinous neoplasm (IPMN)) seem to share many clinicopathological features; however, IPNB has not been fully characterized. In order to understand the clinicopathological/immunohistochemical features of IPNB better, we compared 52 cases of IPNB with 42 cases of IPMNs with mural nodules. The IPNB cases were divided into two groups according to their histological similarity and according to five key histological findings. All IPNB and IPMN cases mainly affected middle-aged to elderly people, predominantly men. Mucin hypersecretion was less frequent in IPNB compared to IPMN. Group 2 IPNB more frequently had a higher histopathological grade and more extensive stromal invasion than IPMN. Group 1 IPNB and IPMN were further classified into four subtypes (gastric, intestinal, pancreatobiliary, and oncocytic). Although each subtype of IPNB and IPMN showed similar histology, the immunohistochemical results were different. The gastric type of IPNB was less frequently positive for CDX2, and intestinal IPNB was more frequently positive for MUC1 and less frequently positive for MUC2, MUC5AC, and CDX2 compared to each subtype of IPMN, respectively. In conclusion, IPNB and IPMN have some clinicopathological features in common, but mucin hypersecretion was less frequent both in IPNBs than in IPMN. Group 2 IPNB differed from IPMN in several parameters of tumor aggressiveness. Additional clinicopathological and molecular studies should be performed with respect to the subtypes of IPNB and IPMN.

Extended RAS analysis and correlation with overall survival in advanced pancreatic cancer

BACKGROUND

Mutations in the KRAS gene can be detected in about 70-90% of pancreatic cancer (PC) cases. Whether these mutations have a prognostic or predictive value remains elusive. Furthermore, the clinical relevance of the extended RAS (KRAS+NRAS) mutational status is unclear in PC.

METHODS

We prospectively defined a PC patient population who received erlotinib-free chemotherapy regimens. A statistically significant difference between KRAS wild-type and KRAS mutated tumours in at least 160 patients in this population would support the assumption of a rather prognostic role of KRAS.

RESULTS

One hundred and seventy-eight tumour samples were collected from prospective clinical studies and successfully analysed for the extended RAS status: 37 tumours were KRAS wild-type (21%), whereas 141 (79%) carried a KRAS mutation; 132 of these mutations were found in KRAS exon 2 (74%), whereas only 9 mutations (5%) were detected in KRAS exon 3. Within KRAS exon 4 and NRAS exons 2-4, no mutations were apparent. There was no significant difference in overall survival for KRAS wild-type vs mutant patients (9.9 vs 8.3 months, P=0.70).

CONCLUSIONS

Together with the results of the AIO-PK-0104-trial, the present analysis supports the notion that KRAS mutation status is rather predictive than prognostic in advanced PC.

Long-term outcome of surgical resection for intraductal papillary neoplasm of the bile duct

BACKGROUND AND AIMS

Intraductal papillary neoplasm of the bile duct (IPNB) is a specific type of bile duct tumor. Studies about the surgical outcomes for IPNB are few; therefore, we investigated the survival of patients who underwent curative surgical resection of IPNB.

METHODS

We retrospectively reviewed the medical and pathological records of 148 IPNB patients who underwent curative-intent hepatic resection between January 2005 and December 2011, to examine the prognosis of IPNB. All demographic and operative parameters were analyzed the effect on survival of patients.

RESULTS

The median survival of IPNB patients was 1326 days with a respective 1, 3, and 5 year overall survival of 83.6% (95%CI: 76.5-88.7), 64.4% (95%CI: 56.0-71.6), and 47% (95%CI: 38.4-55.7). The level of invasiveness of IPNB predicted survival very well. For malignant IPNB, univariate analysis showed that serum CA19-9 level, lymph node metastasis, and completeness of resection were significant prognostic factors. Lymph node metastasis and completeness of resection were found in multivariate analysis to be significantly related to survival of the patients.

CONCLUSIONS

The level of invasiveness and lymph node status were found to be associated with patient survival, as was adequacy of surgery. We recommend R0 resection be attempted for patients with IPNB.

Updates on Precancerous Lesions of the Biliary Tract: Biliary Precancerous Lesion

Precursor lesions of invasive adenocarcinoma of the bile duct (cholangiocarcinoma) have been increasingly recognized during the past decade because of the results of multiple studies on the carcinogenesis of cholangiocarcinoma, technologic advancements in diagnostic imaging modalities, and an increase in the volume of elective procedures. The two main precursor lesions of cholangiocarcinoma that have evolved are biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile duct. These lesions demonstrate histomorphologic similarities to pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasm of the pancreas, respectively, whereas mechanisms of carcinogenesis and risk of progressive disease appear distinct. An enhanced understanding of the clinical presentation and pathologic features of precursor lesions of the biliary tract and use of the correct terminology will facilitate efficient communication between surgeons, oncologists, and pathologists and improve quality of patient care.

Comparative clinicopathological study of biliary intraductal papillary neoplasms and papillary cholangiocarcinomas

AIMS

The aim of this study was to achieve a better definition of intraductal papillary neoplasms of the bile duct (IPNBs).

METHODS AND RESULTS

Biliary tumours that showed predominantly intraductal papillary growth were provisionally classified as IPNBs (n = 25) and papillary cholangiocarcinomas (n = 27). IPNB was defined as a neoplasm that is confined to the epithelium or is regularly arranged in a high-papillary architecture along thin fibrovascular stalks, whereas the term 'papillary cholangiocarcinoma' was used for tumours with more complex papillary structures (e.g. irregular papillary branching or mixed with solid-tubular growth). In our consecutive cohort of biliary neoplasms, 5% were classified as IPNBs, and 10% as papillary cholangiocarcinomas. IPNBs differed from papillary cholangiocarcinomas by less advanced invasion, gross mucin overproduction (72% versus 7%), and their prevalent location (84% of IPNBs in intrahepatic/hilar ducts; 70% of papillary cholangiocarcinomas in extrahepatic ducts). Gastric-type and oncocytic-type tumours were only detected in IPNBs. Expression of mucin core proteins and cytokeratin 20 significantly differed between the two groups. KRAS and GNAS were wild-type genotypes in all but one case of KRAS-mutated IPNB. Patients with IPNB had better recurrence-free survival than those with papillary cholangiocarcinoma (P = 0.007). In multivariate analysis, in which several other prognostic factors (e.g. stromal invasion and lymph node metastasis) were applied, the classification of the two papillary tumours was an independent prognostic factor (P = 0.040).

CONCLUSIONS

Given the significant contrast in clinicopathological features between IPNBs and papillary cholangiocarcinomas, it may be more appropriate to use the diagnostic term 'IPNB' for selected tumours that show regular papillary growth, separately from papillary cholangiocarcinomas.

Distinct pathways of pathogenesis of intraductal oncocytic papillary neoplasms and intraductal papillary mucinous neoplasms of the pancreas

Intraductal oncocytic papillary neoplasm (IOPN) of the pancreas is classified as a variant of intraductal papillary mucinous neoplasm (IPMN) in the WHO guidelines. However, the neoplastic cells of IOPNs are unique, with distinctive architecture/oncocytic cytoplasm. Although molecular/immunohistochemical features of other IPMN variants have been extensively studied, those of IOPNs have not been well characterized. Expression profile of antibodies associated with genetic alterations previously described for ductal adenocarcinomas (DAs) and IPMNs (SMAD4/β-catenin/p53/mesothelin/claudin-4) as well as antibodies to mucins and differentiation markers [MUC1/MUC2/MUC5AC/MUC6/CDX2/hepatocyte paraffin-1 (HepPar-1)] was investigated in 24 IOPNs and 22 IPMNs to assess the similarities/differences between these tumors. Expression of mesothelin and claudin-4 was dissimilar between these tumor types: A higher proportion of IOPNs labeled with mesothelin [21/24 (87.5 %) of IOPNs, 6/22 (27 %) of IPMNs, p < 0.001], while the reverse was true for claudin-4 [2/23 (9 %) of IOPNs, 9/22 (41 %) of IPMNs, p = 0.01]. The results of immunolabeling for SMAD4/β-catenin/p53 were similar in both: None of the cases showed SMAD4 loss in the intraductal components, and only 1/21 (5 %) of IOPNs and 2/22 (9 %) of IPMNs revealed abnormal β-catenin expression (p = 0.49). Nuclear p53 accumulation was seen mostly in architecturally complex/high-grade dysplasia areas in both. Immunolabeling for MUC proteins showed that almost all lesions expressed MUC5AC. Twelve of the 24 (50 %) IOPNs and 6/22 (27 %) of IPMNs (p = 0.11) labeled for MUC1, whereas 7/24 (29 %) of IOPNs and 10/22 (45 %) of IPMNs labeled for MUC2 (p = 0.25). MUC6 was expressed in 8/9 (89 %) of IOPNs (strong) and 6/21 (29 %) of IPMNs (weak) (p = 0.002). Fourteen of the 23 (61 %) IOPNs and 4/22 (18 %) of IPMNs labeled for HepPar-1 (p = 0.003). These results show that IOPNs have distinct immunoprofile and provide support for the proposition that IOPN is a distinct entity developing through a mechanism different from other pancreatic ductal neoplasms.

Uncommon liver tumors: Case report and literature review

BACKGROUND

Beside hepatocellular carcinoma, metastasis, and cholangiocarcinoma, the imaging findings of other relatively uncommon hepatic lesions are less discussed in the literature. Imaging diagnosis of these lesions is a daily challenge. In this article, we review the imaging characteristics of these neoplasms.

METHODS

From January 2003 to December 2014, 4746 patients underwent liver biopsy or hepatic surgical resection in our hospital. We reviewed the pathological database retrospectively. Imaging of these lesions was reviewed.

RESULTS

Imaging findings of uncommon hepatic lesions vary. We discuss the typical imaging characteristics with literature review. Clinical and pathological correlations are also described. Primary hepatic lymphoma consists only of 1% of the extranodal non-Hodgkin lymphoma, and is defined as the one involving only the liver and perihepatic lymph nodes within 6 months after diagnosis. Combined hepatocellular and cholangiocarcinoma (cHCC-CC) shares some overlapping imaging characteristics with both HCC and cholangiocarcinoma because of being an admixture of them. Angiosarcoma is the most common hepatic mesenchymal tumor and is hypervascular in nature. Inflammatory pseudotumor is often heterogeneous on ultrasonography and with enhanced septations and rims in the portovenous phase after contrast medium. Angiomyolipoma (AML) typically presents with macroscopic fat components with low signal on fat-saturated magnetic resonance imaging (MRI) and presence of drainage vessels. Intraductal papillary neoplasm of the bile duct (IPNB) is thought of as a counterpart to the pancreatic intraductal papillary mucinous neoplasm. Most of the IPNBs secrete mucin and cause disproportional dilatation of the bile ducts. Mucinous cystic neoplasm (MCN) contains proteinaceous and colloidal components without ductal communication and characterizes with hyperintensity on T1-weighted imaging. Other extremely rare lesions, including epithelioid hemangioendothelioma and inflammatory pseudotumor-like follicular dendritic cell sarcoma, are also discussed. Hepatoblastoma and mesenchymal hamartoma, mostly in children, are also briefly reviewed as well.

CONCLUSION

It is important for radiologists to be familiar with the typical imaging features of the uncommon hepatic neoplasms. If imaging findings are not typical or diagnostic, further biopsy is required.

Systematic Review and Meta-analysis of Current Experience in Treating IPNB: Clinical and Pathological Correlates

OBJECTIVE

To systematically review studies reporting clinicopathological features of intraductal papillary neoplasm of the bile duct (IPNB) to provide evidence-based guidance for management.

BACKGROUND

IPNB is a rare tumor type. Management decisions are currently based upon anecdotal evidence and small case series. To data, there has been no systematic review of IPNB literature.

METHODS

MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews were searched and data were extracted from relevant studies. Meta-analysis was used to pool study estimates. Evidence of association was determined by comparing pooled crude odds ratios (OR) derived from abstracted data.

RESULTS

Fifty-seven retrospective case series were included. At least 43% of 476 specimens contained invasive disease. Invasive tumors were found at significantly higher frequency in pancreaticobiliary than intestinal, gastric or oncocytic-type IPNB [pooled OR 2.5, 95% confidence interval (CI) 1.5-4.2, P < 0.001]. A significantly higher proportion of pancreaticobiliary tumors compared with intestinal tumors expressed MUC-1 [86.4% (95% CI 75.1%-94.7%) vs 13.2% (95% CI 4.6%-25.2%), respectively P < 0.001]. IPNB identified in centers from Asia were more likely to be intrahepatic and were less frequently invasive compared with those from Western centers. Pooled estimates of absolute survival after IPNB resection were 96% (95% CI 93%-99%) at 1 year, 79% (95% CI 69%-88%) at 3 years, and 65% (95% CI 46%-76%) at 5 years.

CONCLUSIONS

Early surgery is advisable for radiologically suspected IPNB as it is frequently invasive. The pathobiology of IPNB demonstrates geographic variation. Pancreaticobiliary IPNB expresses MUC1 and is more frequently associated with invasive disease than other IPNB subtypes.

Molecular genetics and targeted therapeutics in biliary tract carcinoma

The primary malignancies of the biliary tract, cholangiocarcinoma and gallbladder cancer, often present at an advanced stage and are marginally sensitive to radiation and chemotherapy. Accumulating evidence indicates that molecularly targeted agents may provide new hope for improving treatment response in biliary tract carcinoma (BTC). In this article, we provide a critical review of the pathogenesis and genetic abnormalities of biliary tract neoplasms, in addition to discussing the current and emerging targeted therapeutics in BTC. Genetic studies of biliary tumors have identified the growth factors and receptors as well as their downstream signaling pathways that control the growth and survival of biliary epithelia. Target-specific monoclonal antibodies and small molecules inhibitors directed against the signaling pathways that drive BTC growth and invasion have been developed. Numerous clinical trials designed to test these agents as either monotherapy or in combination with conventional chemotherapy have been completed or are currently underway. Research focusing on understanding the molecular basis of biliary tumorigenesis will continue to identify for targeted therapy the key mutations that drive growth and invasion of biliary neoplasms. Additional strategies that have emerged for treating this malignant disease include targeting the epigenetic alterations of BTC and immunotherapy. By integrating targeted therapy with molecular profiles of biliary tumor, we hope to provide precision treatment for patients with malignant diseases of the biliary tract.

Characterization of intraductal papillary neoplasm of bile duct with respect to histopathologic similarities to pancreatic intraductal papillary mucinous neoplasm

Intraductal papillary neoplasm of bile duct (IPNB) is a papillary tumor covered by well-differentiated neoplastic epithelium with fine fibrovascular cores in the dilated bile ducts. It reportedly shows similarities to intraductal papillary mucinous neoplasm of pancreas (IPMN), to various degrees. Herein, IPNB was pathologically analyzed by classifying 52 cases into 4 groups based on the histopathologic similarities to IPMN: group A (identical to IPMN, 19 cases), group B (similar to but slightly different from IPMN, 18 cases), group C (vaguely similar to IPMN, 5 cases), and group D (different from IPMN, 10 cases). In group A, intrahepatic and perihilar regions were mainly affected, most cases were of low/intermediate or high grade without invasion, and gastric type was the most common phenotype, followed by oncocytic and intestinal types. In groups C and D, perihilar and distal bile ducts were affected, almost all cases were of high grade with invasion, and most of them were of intestinal and pancreatobiliary phenotypes. Most group B cases were of intestinal phenotype, and all were of high grade with or without invasion. In conclusion, these 4 groups of IPNB showed unique pathologic features and behaviors. Group A cases were less aggressive and shared many features with IPMN, whereas group C and D cases were more aggressive and mainly found in perihilar and distal bile ducts. Group B resembling IPMN was intermediate between them. This classification may be useful in clinical practice and holds promise for a novel approach to analyze IPNB tumorigenesis.

Intraductal papillary neoplasm of the bile ducts: A case report and literature review

Intraductal papillary neoplasm of the bile duct (IPNB) is a rare bile duct neoplasm mostly found in far eastern nations where hepatolithiasis and clonorchiasis infections are endemic. In western countries, it is very rare and the etiology is unknown. In this article, we report the first IPNB patient we encountered in our clinic and a literature review. The patient is a 38-year-old female with a history of choledocholithiasis who presented with obstructive jaundice. She was found to have a papillary mass at the junction of the right hepatic duct and common hepatic duct with six masses in the liver parenchyma. The immunophenotypic and histologic features of the tumor are consistent with IPNB, gastric subtype. The patient had a partial hepatectomy and has been receiving palliative chemotherapy. In a search of PubMed database, we collected 354 IPNB patients reported in 22 articles. In these patients, 52.8% were from Japan and 27.7% were from western countries including the United States (11.0%). The age of the patients ranged from 35 to 80 years old with an average of 64.6. Male/female ratio was 1.5. Macroscopically, 57.5% of the tumors were in the left lobe and 29.5% were in the right lobe. The average size of the tumor were 4.2 cm at the time of diagnosis. Histologically, pancreato-biliary subtype accounted for 41.8%, intestinal 28.0%, gastric 13.5% and oncocytic 16%. An invasive component is most often present in the pancreato-biliary and gastric subtypes. Despite recent advanced technologies, diagnosis of IPNB is still challenging, especially in western countries due to its rarity. Defined clinico-pathologic features are in demand for the accurate diagnosis and proper treatment.

Tubular adenoma of the common bile duct with uptake in 18F-FDG PET: A case report

A 64-year-old man presented with epigastric discomfort and nausea. Laboratory analyses revealed increased levels of total and direct bilirubin, and increased levels of aminotransferases. Computed tomography revealed the presence of a mass in the distal common bile duct. Endoscopic retrograde cholangiopancreatography and intraductal ultrasonography revealed a 25 mm filling defect in the distal common bile duct, and biopsy of the lesion disclosed the presence of tubular adenoma. Using fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) revealed an increased accumulation of the tracer in the lesion, with a maximum standard uptake value (SUV_max) of 3.3. The patient received a pylorus-preserving pancreatoduodenectomy. The histopathological examination revealed a tubular adenoma with low-grade atypia. The patient remains alive 15 months following the surgery, with no evidence of recurrence of the adenoma. ¹⁸F-FDG PET has been successfully applied in clinical practice to detect a wide variety of tumor types, including lymphoma, lung, colon and bile duct cancer. In the present study, a case of bile duct adenoma with low-grade atypia was reported, revealing the uptake of ¹⁸F-FDG. ¹⁸F-FDG PET may be able to detect premalignant tumors of the bile duct, although whether ¹⁸F-FDG PET is able to differentially discriminate between diagnoses of adenoma and carcinoma of the bile duct remains to be fully elucidated, and the assessment of further case studies is required.

Clinical and biological significance of precursor lesions of intrahepatic cholangiocarcinoma

Cholangiocarcinoma (CC) is primarily a malignant tumor of older adults most prevalent in Southeast Asia, where liver fluke infestation is high. However the etiology in western countries is unknown. Although the incidence of extrahepatic cholangiocarcinoma has remained constant, incidence of intrahepatic CC (ICC) which differs in morphology, pathogenesis, risk factors, treatment and prognosis is increasing. While this increase is associated with hepatitis C virus infection, chronic nonalcoholic liver disease, obesity, and smoking, the pathogenesis of ICC and molecular alterations underlying the carcinogenesis are not completely elucidated. Benign biliary lesions such as biliary intraepithelial neoplasia, intraductal papillary neoplasm of the bile duct, von Meyenburg complex or bile duct hamartoma, and bile duct adenoma have been associated with ICC. For each of these entities, evidence suggests or supports a role as premalignant lesions. This article summarized the important biological significance of the precursor lesions of ICC and the molecular mechanisms that may be involved in intrahepatic cholangiocarcinogenesis.

GNAS and KRAS mutational analyses of intraductal papillary neoplasms of the pancreas and bile duct developing in the same individual: A case report

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas and intraductal papillary neoplasm of the bile duct (IPNB) are considered as counterparts of each other, and it is suggested that these two entities have similar molecular alteration pathways. However, the occurrence of IPMN of the pancreas and IPNB in the same patient is rare. We report a surgical case of a 69-year-old woman who developed invasive IPMN of the pancreas and underwent pancreatectomy, 6 months after hepatic resection of invasive IPNB. Molecular analysis revealed GNAS/KRAS mutation in both invasive IPMN of the pancreas and IPNB. This is believed to be the first case report investigating GNAS/KRAS mutational status in both IPMN of the pancreas and IPNB developing in the same patient, and these two entities may show similar molecular alternations.

Intraductal tubulopapillary neoplasms of the bile ducts: clinicopathologic, immunohistochemical, and molecular analysis of 20 cases

Intraductal tubulopapillary neoplasm is a well-established entity in the pancreas. A similar, if not identical, tumor occurs also in the biliary tract. We conducted a multicenter study of 20 such lesions, focusing on their clinicopathologic characteristics and molecular profile. Biliary intraductal tubulopapillary neoplasms were seen in patients in their 60s (mean 62 years). The tumors were intrahepatic 70%, extrahepatic 10%, and perihilar 20%; mean tumor size was 6.9 cm. Histologically, all intraductal tubulopapillary neoplasms showed, in addition to their typical tubular pattern, solid areas (70%) or abortive papillae (50%). Necrosis was common (85%), predominantly focal (40%), and with 'comedocarcinoma-like pattern' in 40%. Immunohistochemically, these neoplasms were characterized by the expression of MUC1 (80%) and MUC6 (30%) and by the absence of MUC2 and MUC5AC. Associated invasive carcinomas were present in 16 (80%), mainly conventional tubular adenocarcinoma (50%). The molecular alterations observed included CDKN2A/p16 (intraductal components 44%, invasive 33%) and TP53 (intraductal components 17%, invasive 9%). Mutations in KRAS (intraductal 6%, invasive 0%), PIK3CA (intraductal 6%, invasive 0%), and loss of SMAD4/DPC4 (intraductal 7%, invasive 0%) were rare. No alterations/mutations were identified in IDH1/2, BRAF, GNAS, EGFR, HER2, and β-catenin. Follow-up information was available for 17 patients (85%) with mean follow-up 44 months. Overall combined survival rates showed favorable prognosis: 1 year 100%, 3 years 90%, and 5 years 90%. In conclusion, despite the relatively high incidence of invasive carcinoma (80%), available follow-up suggests that biliary intraductal tubulopapillary neoplasms have an indolent behavior. Molecular analyses highlight the low prevalence of alterations of common oncogenic signaling pathways in intraductal tubulopapillary neoplasm. Further studies using whole-exome sequencing are required to discover yet unknown molecular changes and to understand the carcinogenesis of intraductal tubulopapillary neoplasms.

A rare cause of dilated bile duct incidentally detected on imaging

Adenomas involving the extrahepatic bile ducts are rare benign tumours of the biliary tract. Given the asymptomatic nature of these tumours and the natural progression of biliary adenoma to carcinoma including cholangiocarcinoma, early detection is challenging. We present a case of an octogenarian woman with a remote history of gallstones who initially presented to the gastroenterology office for an incidental finding of biliary dilation, and whose subsequent imagings and biopsy suggested common bile adenoma. However, the patient was deemed a poor surgical candidate for pancreaticoduodenectomy, and unfortunately represented 5 months later with findings suggesting cholangiocarcinoma. This case provides a unique opportunity to study the natural progression of biliary adenoma to cholangiocarcinoma.

Intraductal papillary neoplasms of the bile duct

Intraductal papillary neoplasm of the bile duct (IPNB) is a rare variant of bile duct tumors characterized by papillary growth within the bile duct lumen and is regarded as a biliary counterpart of intraductal papillary mucinous neoplasm of the pancreas. IPNBs display a spectrum of premalignant lesion towards invasive cholangiocarcinoma. The most common radiologic findings for IPNB are bile duct dilatation and intraductal masses. The major treatment of IPNB is surgical resection. Ultrasonography, computed tomography, magnetic resonance image, and cholangiography are usually performed to assess tumor location and extension. Cholangioscopy can confirm the histology and assess the extent of the tumor including superficial spreading along the biliary epithelium. However, pathologic diagnosis by preoperative biopsy cannot always reflect the maximum degree of atypia, because IPNBs are often composed of varying degrees of cytoarchitectural atypia. IPNBs are microscopically classified into four epithelial subtypes, such as pancreatobiliary, intestinal, gastric, and oncocytic types. Most cases of IPNB are IPN with high-grade intraepithelial neoplasia or with an associated invasive carcinoma. The histologic types of invasive lesions are either tubular adenocarcinoma or mucinous carcinoma. Although several authors have investigated molecular genetic changes during the development and progression of IPNB, these are still poorly characterized and controversial.

Intraductal papillary neoplasm of the bile duct

Intraductal papillary neoplasm of the bile duct (IPNB) is a variant of bile duct carcinoma that is characterized by intraductal growth and better outcomes compared with common cholangiocarcinoma. IPNBs are mainly found in patients from Far Eastern areas, where hepatolithiasis and clonorchiasis are endemic. According to the immunohistochemical profiles of the mucin core proteins, IPNBs are classified into four types: pancreaticobiliary, intestinal, gastric, and oncocytic. Approximately 40%-80% of IPNBs contain a component of invasive carcinoma or tubular or mucinous adenocarcinoma, suggesting that IPNB is a disease with high potential for malignancy. It is difficult to make an accurate preoperative diagnosis because of IPNB’s low incidence and the lack of specificity in its clinical manifestation. The most common abnormal preoperative imaging findings of IPNB are intraductal masses and the involvement of bile duct dilation. Simultaneous proximal and distal bile duct dilation can be detected in some cases, which has diagnostic significance. Cholangiography and cholangioscopy are needed to confirm the pathology and demonstrate the extent of the lesions. However, pathologic diagnosis by biopsy cannot reflect the actual stage in many cases because different foci may be of different stages and because mixed pathologic findings may exist in the same lesion. Surgical resection is the major treatment. Systematic cholangioscopy with staged biopsies and frozen sections is recommended during resection to ensure that no minor tumors are left and that curative resection is achieved. Staging, histologic subtype, curative resection and lymph node metastasis are factors affecting long-term survival.