Pathological observations of intrahepatic peribiliary glands in 1,000 consecutive autopsy livers. II. A possible source of cholangiocarcinoma

Panic at the Bile Duct: How Intrahepatic Cholangiocytes Respond to Stress and Injury

In the liver, biliary epithelial cells (BECs) line intrahepatic bile ducts (IHBDs) and are primarily responsible for modifying and transporting hepatocyte-produced bile to the digestive tract. BECs comprise only 3% to 5% of the liver by cell number but are critical for maintaining choleresis through homeostasis and disease. To this end, BECs drive an extensive morphologic remodeling of the IHBD network termed ductular reaction (DR) in response to direct injury or injury to the hepatic parenchyma. BECs are also the target of a broad and heterogenous class of diseases termed cholangiopathies, which can present with phenotypes ranging from defective IHBD development in pediatric patients to progressive periductal fibrosis and cancer. DR is observed in many cholangiopathies, highlighting overlapping similarities between cell- and tissue-level responses by BECs across a spectrum of injury and disease. The following core set of cell biological BEC responses to stress and injury may moderate, initiate, or exacerbate liver pathophysiology in a context-dependent manner: cell death, proliferation, transdifferentiation, senescence, and acquisition of neuroendocrine phenotype. By reviewing how IHBDs respond to stress, this review seeks to highlight fundamental processes with potentially adaptive or maladaptive consequences. A deeper understanding of how these common responses contribute to DR and cholangiopathies may identify novel therapeutic targets in liver disease.

Challenges in Diagnosing and Reporting Cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a challenge to the practicing surgical pathologist for several reasons. It is rare in many parts of the world, and thus practical exposure may be limited. Related to the fact of its rarity is the fact that more common tumors which frequently metastasize to the liver can be morphologically indistinguishable (eg, pancreatic ductal adenocarcinoma). Immunohistochemical testing is generally non-contributory in this context. Other difficulties arise from the protean morphologic manifestations of cholangiocarcinoma (ie, small duct vs. large duct) and the existence of combined cholangiocarcinoma and hepatocellular carcinoma. These, and other issues of concern to the practicing diagnostic pathologist are discussed herein.

Imaging of Benign Hepatic lesions

As abdominal imaging volumes have increased, the incidence of incidentally identified benign hepatic lesions has substantially increased. Familiarity with imaging appearances of benign hepatic tumors, both common and less commonly encountered, allows the radiologist to give an informed differential diagnosis. In addition to clinical history, awareness of imaging findings of benign hepatic lesions on ultrasound, computed tomography and magnetic resonance imaging is useful in evaluating these lesions and avoiding unnecessary diagnostic interventions or imaging surveillance.

Peribiliary glands pathology in a large series of end-stage alcohol-related liver disease

The peribiliary glands are intramural or extramural structures with multiple functions related to bile secretion. The peribiliary glands can develop cystic alterations in several conditions, such as alcohol addiction. Peribiliary cysts can enlarge till being radiologically visible and mimic cancer. We studied 217 consecutive explanted livers for end-stage alcohol-related liver disease from the Pathology Unit of the Liver Unit at the King's College Hospital in Denmark Hill, with particular focus on peribiliary glands. Our cohort consisted of 31 females and 186 males, with a median age of 51 and of 56 years respectively. 92,2% had established cirrhosis, 73,3% had only alcohol-induced liver disease, whilst 26,7% had other co-morbidities. We found a mild ectasia of the peribiliary glands (<2 mm) in 37,8% and peribiliary cysts (> = 2 mm) in 22,6% of cases. The diameter of the peribiliary glands varied from 1 mm to 8 mm. Inflammation of the peribiliary glands was found in the majority of cases with dilatation (p value = 0,000). 4,6% of the peribiliary cysts had low-grade intraductal papillary neoplasm of the bile ducts confined to the peribiliary glands. Pancreatic heterotopia was found in 10,6% and associated with the presence of ectasia. Our findings fit with what is reported in literature, such as the alcohol-induced damage at the peribiliary glands. Moreover these results underline the possible role of peribiliary glands in the development of the intraductal papillary neoplasm of the bile ducts, the biliary counterpart of the branch type intraductal mucinous neoplasm of the pancreas.

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

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.

Common features between neoplastic and preneoplastic lesions of the biliary tract and the pancreas

the bile duct system and pancreas show many similarities due to their anatomical proximity and common embryological origin. Consequently, preneoplastic and neoplastic lesions of the bile duct and pancreas share analogies in terms of molecular, histological and pathophysiological features. Intraepithelial neoplasms are reported in biliary tract, as biliary intraepithelial neoplasm (BilIN), and in pancreas, as pancreatic intraepithelial neoplasm (PanIN). Both can evolve to invasive carcinomas, respectively cholangiocarcinoma (CCA) and pancreatic ductal adenocarcinoma (PDAC). Intraductal papillary neoplasms arise in biliary tract and pancreas. Intraductal papillary neoplasm of the biliary tract (IPNB) share common histologic and phenotypic features such as pancreatobiliary, gastric, intestinal and oncocytic types, and biological behavior with the pancreatic counterpart, the intraductal papillary mucinous neoplasm of the pancreas (IPMN). All these neoplastic lesions exhibit similar immunohistochemical phenotypes, suggesting a common carcinogenic process. Indeed, CCA and PDAC display similar clinic-pathological features as growth pattern, poor response to conventional chemotherapy and radiotherapy and, as a consequence, an unfavorable prognosis. The objective of this review is to discuss similarities and differences between the neoplastic lesions of the pancreas and biliary tract with potential implications on a common origin from similar stem/progenitor cells.

Peribiliary Glands as the Cellular Origin of Biliary Tract Cancer

The identification of the cellular origin of cancer is important for our understanding of the mechanisms regulating carcinogenesis, thus the cellular origin of cholangiocarcinoma (CCA) is a current topic of interest. Although CCA has been considered to originate from biliary epithelial cells, recent studies have suggested that multiple cell types can develop into CCA. With regard to the hilar and extrahepatic bile ducts, peribiliary glands (PBGs), a potential stem cell niche of biliary epithelial cells, have attracted attention as the cellular origin of biliary tract cancer. Recent histopathological and experimental studies have suggested that some kinds of inflammation-induced CCA and intraductal papillary neoplasms of the bile duct are more likely to originate from PBGs. During inflammation-mediated cholangiocarcinogenesis, the biliary epithelial injury-induced regenerative response by PBGs is considered a key process. Thus, in this review, we discuss recent advances in our understanding of cholangiocarcinogenesis from the viewpoint of inflammation and the cellular origin of CCA, especially focusing on PBGs.

Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree

Cholangiocarcinoma (CC) is a type of relatively rare neoplasm in adenocarcinoma. The characteristics of CCs as well as biliary epithelial cells are heterogeneous at the different portion of the biliary tree. There are two candidate stem/progenitor cells of the biliary tree, i.e., biliary tree stem/progenitor cell (BTSC) at the peribiliary gland (PBG) of large bile ducts and liver stem/progenitor cell (LPC) at the canals of Hering of peripheral small bile duct. Although previous reports suggest that intrahepatic CC (ICC) can arise from such stem/progenitor cells, the characteristic difference between BTSC and LPC in pathological process needs further investigation, and the etiology of CC remains poorly understood. Here we show that Sterile alpha motif domain containing 5 (SAMD5) is exclusively expressed in PBGs of large bile ducts in normal mice. Using a mouse model of cholestatic liver disease, we demonstrated that SAMD5 expression was upregulated in the large bile duct at the hepatic hilum, the extrahepatic bile duct and PBGs, but not in proliferating intrahepatic ductules, suggesting that SAMD5 is expressed in BTSC but not LPC. Intriguingly, human ICCs and extrahepatic CCs exhibited striking nuclear localization of SAMD5 while the normal hilar large bile duct displayed slight-to-moderate expression in cytoplasm. In vitro experiments using siRNA for SAMD5 revealed that SAMD5 expression was associated with the cell cycle regulation of CC cell lines. Conclusion: SAMD5 is a novel marker for PBG but not LPC in mice. In humans, the expression and location of SAMD5 could become a promising diagnostic marker for the cell type as well as malignancy of bile ducts and CCs.

Latest advances in the pathological understanding of cholangiocarcinomas

Cholangiocarcinomas (CCAs) are anatomically classified into intrahepatic, perihilar, and distal types. The gross pathological classification of intrahepatic CCAs divides them into mass-forming, periductal-infiltrating, and intraductal-growth types; and perihilar/distal CCAs into flat- and nodular-infiltrating and papillary types. Unique preinvasive lesions appear to precede individual gross types of CCA. Biliary intraepithelial neoplasia, a flat lesion, precedes periductal-, flat-, and nodular-infiltrating CCAs, whereas intraductal papillary neoplasm of the bile duct (IPNB) precedes the intraductal-growth and papillary type of CCAs. IPNBs are heterogeneous in their histological and pathological profiles along the biliary tree. Hepatobiliary cystadenomas/adenocarcinomas are reclassified as cystic IPNBs and hepatic mucinous cystic neoplasms. Peribiliary glands may participate in the development of CCAs. These latest findings present a new challenge for understanding the pathology of CCAs.

Cystic and Papillary Neoplasm at the Hepatic Hilum Possibly Originating in the Peribiliary Glands

Cystic neoplasms of the liver are divided into two types: mucinous cystic neoplasm and cystic intraductal papillary neoplasm of the bile duct. We herein report two cases of cystic and papillary neoplasm of the liver which differed from the abovementioned types. Case  1. A 70-year-old man. Radiologically, a cystic tumor measuring 20 mm in diameter was found at the hepatic hilum. Right hepatectomy was performed under a diagnosis of intrahepatic cholangiocarcinoma (iCCA) based on the imaging findings. Case  2. A 70-year-old man. Radiologically, a cystic tumor measuring 60 mm in diameter was found at the hepatic hilum. Under a diagnosis of iCCA, left hepatic trisectionectomy was performed. In both cases, endoscopic retrograde cholangiography did not demonstrate communication between the cystic tumor and adjacent bile ducts. Pathologically, these two tumors were cystic neoplasms located at the hepatic hilum and were morphologically characterized by an intracystic papillary neoplasm composed of diffuse high-grade dysplasia and associated with an invasive carcinoma. Ovarian-like stroma was not found in the capsule of these tumors. Interestingly, there were peribiliary glands near these tumors, and MUC6 was expressed in these papillary neoplasms as well as in the peribiliary glands. These neoplasms might have arisen from the peribiliary glands.

Human ductal plate and its derivatives express antigens of cholangiocellular, hepatocellular, hepatic stellate/progenitor cell, stem cell, and neuroendocrine lineages, and proliferative antigens

Molecular mechanisms of human ductal plate (DP) development and differentiation (DD) are unclear. The author immunohistochemically investigated expressions of cholangiocellular antigens (CEA, CA19-9, EMA, MUC1, MUC2, MUC5AC, MUC6, mucins, CK7, and CK19), hepatocellular antigens (HepPar1, AFP, CK8, and CK18), hepatic stellate/progenitor cell (HSC) antigens or stem cell (SC) antigens (C-erbB2, CD56, chromogranin, synaptophysin, bcl2, NSE, NCAM, KIT, and PDGFRA), and proliferating antigen (Ki67) in 32 human fetal livers (HFL). The DD of human intrahepatic bile duct (IBD) could be categorized into four stages: DP, remodeling DP, remodeled DP, and immature IBD. All the molecules examined were expressed in the DP and DP derivatives. These results suggest that human DP or DP derivatives have capacities to differentiate into cholangiocellular, hepatocellular, HSC, SC, and neuroendocrine lineages. The data also suggest that NCAM, KIT/SC factor-signaling, NSE, HGF/MET signaling, PDGFa/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of DP and biliary cells of HFL. DP, DP derivatives, and IBD in HFL have proliferative capacity.

Cystic micropapillary neoplasm of peribiliary glands with concomitant perihilar cholangiocarcinoma

We report a case of a 75-year-old man with cystic micropapillary neoplasm of peribiliary glands detected preoperatively by radiologic examination. Enhanced computed tomography showed a low-density mass 2.2 cm in diameter in the right hepatic hilum and a cystic lesion around the common hepatic duct. Under a diagnosis of perihilar cholangiocarcinoma, right hepatectomy with caudate lobectomy and bile duct resection were performed. Pathological examination revealed perihilar cholangiocarcinoma mainly involving the right hepatic duct. The cystic lesion was multilocular and covered by columnar lining epithelia exhibiting increased proliferative activity and p53 nuclear expression; it also contained foci of micropapillary and glandular proliferation. Therefore, the lesion was diagnosed as a cystic micropapillary neoplasm of peribiliary glands and resembled flat branch-type intraductal papillary mucinous neoplasm of the pancreas. Histological examination showed the lesion was discontinuous with the perihilar cholangiocarcinoma. Immunohistochemistry showed the cystic neoplasm was strongly positive for MUC6 and that the cholangiocarcinoma was strongly positive for MUC5AC and S100P. These results suggest these two lesions have different origins. This case warrants further study on whether this type of neoplasm is associated with concomitant cholangiocarcinoma as observed in pancreatic intraductal papillary mucinous neoplasm with concomitant pancreatic duct adenocarcinoma.

Development of extrahepatic bile duct excluding gall bladder in human fetuses: histological, histochemical, and immunohistochemical analysis

BACKGROUND

The fetal development of extrahepatic bile ducts (EBD) is unkown.

MATERIALS AND METHODS

Development of EBD was examined by immunohistochemistry in 16 fetuses of 7-40 gestational week (GW). Gall bladder (GB) was not investigated.

RESULTS

At seven GW, a hepato-pancreatic bud (HPB) was seen near the hepatic hilus. At eight GW, embryonic EBD, GB and pacreas developed from HPB. Portal veins (PV) and hepatic arteries (HAs) were present in EBD at eight GW. Liver parenchyma was already present in seven GW. At eight GW, EBD at porta hepatis (PH) was already established; PH EBD was derived from ductal plate (DP). The distal and middle EBD gradually develeped and took shape of EBD at nine GW. In PH, cystic and hepatic ducts developed from DP at eight GW. EBD developed further, accompanying many nerve fibers (NF) at PH and distal and middle EBD. Apparent PV and HA were seen around 12 GW. Around 20 GW, HA and capillaries proliferated, giving rise to peribiliary capillary plexus (PCP) in all parts of EBD. EBD grew gradually further, and around 30 GW extrahepatic peribiliary glands (EPG) emerged from EBD but not from cystic duct. Around 36 GW, exocrine pancreatic acinar cells emerged from remodeled DP at PH. At term (40 GW), EBD was established but was as yet immature. Numerous NF were present around EBD. Histochemically, EBD epithelium had no mucins at 7-12 GW but contained neutral and acidic mucins at 23-40 GW. EPG had abundant neutral and acidic mucins. Immunohistochemically, alpha-fetoprotein (AFP) was consistently positive in the epithelial and mesenychyma. The NF and muscles of HPB present at seven GW were positive for neural cell adhesion molecule (NCAM), neuron-specific enolase (NSE), platelet-derived growth factor receptor-α (PDGFRA), and KIT, but they disappeared in nine GW. Expressions of cytokeratin (CK) seven and CK19 in EBD and EPG were slight or none, while expression of CK8 was moderate, and that of CK18 was strong. NF were positive for NCAM, NSE, synaptophysin, and chromogranin, and PDGFRA. MUC1 and MUC6 apomucins were noted in EBD and EPG. EPG contained numerous endocrine cells positive for chromogranin, synaptophysin, NCAM and NSE. A few endocrine cells positive for these antigens were seen in EBD. Numeous KIT-positive stem cells (SC) were seen in PH, EBD, PV, HA, PCP, and EPG. NCAM-positive and bcl-2-positive SC were also located in these structures. Epithelial cells of EBD and EPG showed expressions of MET, PDGFRA, CA19-9, MUC1, MUC2, MUC6, KIT, bcl-2, and ErbB2. No expressions of HepPar1, carcinoembryonic antigen (CEA), and epithelial membrane antigen (EMA) were noted.

CONCLUSIONS

Although the findings have limitatios because this study of humans are descriptive one, the present data suggest that the processes of the development and differentiation of EBD system may be associated with EBD SC, CK prolifes, SFC/KIT signaling, HGF/MET signaling, PDGRa/PDGFRA signaling, fibroblast growth factor/ErbB2 signaling, neuroendocrine lineage, NF differentiation, pancreatic aninar cell differentiation, PCP differentiation, MUC apomucins differentiation, and expressions of AFP and CA19-9. HepPar1, EMA and CEA were not involved in them.

Human fetal ductal plate revisited. I. ductal plate expresses NCAM, KIT, MET, PDGFRA, and neuroendocrine antigens (NSE, chromogranin, synaptophysin, and CD56)

BACKGROUND

The molecular mechanisms of ductal plate (DP) development and differentiation (DD) in human fetal livers (HFLs) are unclear.

MATERIALS AND METHODS

The author immunohistochemically investigated expressions of NCAM, KIT, KIT, PDGFRA, and neuroendocrine antigens in 32 HFLs.

RESULTS

The processes of human intrahepatic bile duct (IBD) DD could be categorized into four stages: DP, remodeling DP, remodeled DP, and mature IBD. NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. The biliary elements were positive for cytokeratin (CK)7, 8, 18, and 19. The hepatoblasts were positive for CK8 and CD18, but negative for CK7 and CK19; however, periportal hepatoblasts showed biliary-type CKs (CK7 and CK19). NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. KIT was occasionally (12/32 cases) expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. NCAM expression was also seen in some hepatoblasts and hematopoietic cells and neurons. KIT was also expressed in some hepatoblasts, hematopoietic cells, and mast cells. MET and PDGFRA were strongly expressed in DP, remodeling DP, remodeled DP, and mature IBD. MET and PDGFRA were also strongly expressed in hepatoblasts and hematopoietic cells. MET and PDGFRA were not expressed in portal mesenchyme, portal veins, sinusoids, and hepatic veins. DP showed immunoreactive chromogranin, synaptophysin, neuron-specific enolase (NSE), and CD56. Expressions of chromogranin and CD56 were infrequently seen in remodeling DP. No expressions of these four neuroendocrine antigens were seen in remodeled DP and mature IBD. The nerve fibers were consistently positive for chromogranin, synaptophysin, NSE, and CD56 in the portal mesenchyme in the stages of remodeling DP, remodeled DP, and mature IBDs.

CONCLUSIONS

The data suggest that NCAM, KIT/stem cell factor-signaling, NSE, hepatocyte growth factor/MET signaling, PDGFα/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of biliary cells of HFL. They also suggest that the DP cells having neuroendocrine molecules give rise to hepatic stem/progenitor cells.

Cystic and micropapillary epithelial changes of peribiliary glands might represent a precursor lesion of biliary epithelial neoplasms

A tumorigenic role of peribiliary glands (PBGs) has been suggested recently. This study was performed to clarify the histological characteristics of PBGs showing cystic and micropapillary epithelial changes. From histological sections of a total of 938 autopsy livers, cases with cystic and micropapillary changes of the epithelial cells of intrahepatic PBGs were collected. PBGs with cystic change that lacked micropapillary epithelial changes were referred to as cystic lesion. Mucin staining and immunohistochemical analysis were performed, and the results were compared between cystic and micropapillary (C-P) lesions and cystic lesions. C-P and cystic lesions were observed in 9 (1 %) and 40 (4 %) , respectively. The atypia of micropapillary epithelium was usually mild, but in a single case, invasive adenocarcinoma accompanied a C-P lesion. Abundant mucin expression was observed in all cases of C-P lesion, which was similar to mucinous acini of normal PBGs rather than serous acini. Immunohistochemical analysis showed that MUC5AC was more frequently expressed in C-P lesions than in cystic lesions. Immunohistochemical expression of cyclin D1 and S100P was characteristically found in C-P lesions. Mean Ki-67 labeling index of C-P lesions was significantly higher than that of cystic lesions. The immunoprofile of C-P lesions was similar to that of the branch-type intraductal papillary mucinous neoplasm of the pancreas. These results suggest that C-P lesions may have neoplastic features and might represent a precursor of biliary epithelial neoplasms, including branch-type intraductal papillary neoplasm of the bile duct as well as mucin-producing cholangiocarcinoma, a concept that we have recently proposed.

Peribiliary cysts developed in normal underlying liver: report of a case

Peribiliary cysts, known as cystic dilatation, of the extramural peribiliary glands of the bile duct are rare, and are usually detectable under conditions of pre-existing hepatobiliary diseases such as liver cirrhosis. Preoperative diagnosis is often difficult, because they are usually asymptomatic. Distinction of peribiliary cysts from premalignant or malignant cystic lesions is mandatory. Herein, we report a case of peribiliary cyst, which was preoperatively assumed as unilobar Caroli's diseases in healthy young patients and briefly discuss the management of the condition.

Participation of peribiliary glands in biliary tract pathophysiologies

AIM: To investigate the roles of peribiliary glands around the bile ducts in the pathophysiology of the biliary tract.

METHODS: The expression of fetal pancreatic markers, pancreatic duodenal homeobox factor 1 (PDX1) and hairy and enhancer of split 1 (HES1) and endodermal stem/progenitor (S/P) cell markers [CD44s, chemokine receptor type 4 (CXCR4), SOX9 and epithelial cell adhesion molecule (EpCAM)] were examined immunohistochemically in 32 normal adult livers (autopsy livers) and 22 hepatolithiatic livers (surgically resected livers). The latter was characterized by the proliferation of the peribiliary glands. Immunohistochemistry was performed using formalin-fixed, paraffin-embedded tissue sections after deparaffinization. Although PDX1 and HES1 were expressed in both the nucleus and cytoplasm of epithelial cells, only nuclear staining was evaluated. SOX9 was expressed in the nucleus, while CD44s, CXCR4 and EpCAM were expressed in the cell membranes. The frequency and extent of the expression of these molecules in the lining epithelia and peribiliary glands were evaluated semi-quantitatively based on the percentage of positive cells: 0, 1+ (focal), 2+ (moderate) and 3+ (extensive).

RESULTS: In normal livers, PDX1 was infrequently expressed in the lining epithelia, but was frequently expressed in the peribiliary glands. In contrast, HES1 was frequently expressed in the lining epithelia, but its expression in the peribiliary glands was focal, suggesting that the peribiliary glands retain the potential of differentiation toward the pancreas and the lining epithelia exhibit properties to inhibit such differentiation. This unique combination was also seen in hepatolithiatic livers. The expression of endodermal S/P cell markers varied in the peribiliary glands in normal livers: SOX9 and EpCAM were frequently expressed, CD44s infrequently, and CXCR4 almost not at all. The expression of these markers, particularly CD44s and CXCR4, increased in the peribiliary glands and lining epithelia in hepatolithiatic livers. This increased expression of endodermal S/P cell markers may be related to the increased production of intestinal and gastric mucin and also to the biliary neoplasia associated with the gastric and intestinal phenotypes reported in hepatolithiasis.

CONCLUSION: The unique expression pattern of PDX1 and HES1 and increased expression of endodermal S/P cell markers in the peribiliary glands may be involved in biliary pathophysiologies.

Intrahepatic cholangiocarcinoma with predominant "ductal plate malformation" pattern: a new subtype

Ten cases of intrahepatic cholangiocarcinoma showing a highly differentiated adenocarcinoma mimicking ductal plate malformation (DPM) are reported. The patients included 7 males and 3 females with an average age of 69.5 years. Six cases were associated with chronic liver disease and the remaining 4 cases showed mild fatty change in the parenchyma and/or minimal to mild portal inflammation. Grossly, the tumor was a single nodule 1.5 to 6.6 cm in diameter, and was whitish and solid without a fibrous capsule. Microscopically, the tumor was composed of many vague, small nodular carcinomatous areas with desmoplastic reactions, and neoplastic glands had an irregularly dilated lumen lined with a single layer of cuboidal or low columnar carcinoma cells and irregular protrusions and bulges, resembling DPM. At its border, the carcinoma seemed to replace the non-neoplastic hepatic lobules or regenerative nodules. The central parts of the tumor were variably hypocellular and fibrotic. Although these carcinomas were negative for mucin and HepParI, they were frequently positive for CK19, epithelial cell adhesion molecule, and epithelial membrane antigen. Neural cell adhesion molecule was also expressed variably. The Ki-67 labeling index was <10% and p53 was scarcely expressed. In conclusion, a new subtype of intrahepatic cholangiocarcinoma with predominant DPM pattern was identified.

Intraductal papillary neoplasm arising from peribiliary glands connecting with the inferior branch of the bile duct of the anterior segment of the liver

Intraductal papillary neoplasms of the bile duct are generally thought to arise from neoplastic papillary proliferation of epithelial cells lining the bile duct. We herein report a case with findings that strongly suggested that the biliary cystic tumor might have derived from a peribiliary gland. A 69-year-old female was found to have a cystic lesion with intracystic protrusions at the anterior segment of the right hepatic lobe and underwent hepatic anterior segment resection. Fluoroscopy of the resected specimen injected with contrast medium into the cyst revealed a connection between the cystic lesion and the bile ducts. The cyst was multilocular in appearance. On microscopic examination, the cyst was located within the portal tract of the inferior branch of the anterior segment and connected with the inferior branch of the bile duct. The wall of the hepatic cyst lacked an ovarian-like stroma. The tumor was composed of papillary and glandular components, and the tumor cells were similar to gastric foveolar and pyloric gland epithelia and regarded as adenoma. These tumor cells were positive for MUC 5AC, MUC6, and HIK1083. The tumor was finally diagnosed as an intraductal papillary neoplasm of the bile duct (adenoma, gastric type) arising from a peribiliary gland.

[Intrahepatic biliary cystic lesions]

Intrahepatic biliary cysts encompass a large lesional spectrum including hereditary diseases as polycystic liver disease or Caroli's syndrome, malformative lesions as non hereditary Caroli's disease or simple biliary cyst and true neoplastic lesions as cystadenoma or cystadenocarcinoma. The diagnostic approach of these lesions relies firstly on imaging. Nevertheless, the pathologist not exceptionally receives surgical specimens from cystic fenestration or liver specimen resection with one or several cystic lesions. The clues for pathological diagnosis of these lesions have to be known by pathologists. As regards neoplastic cystic lesions, true non-communicating cystic tumors and cystic variants of intraductal biliary tumors have to be distinguished; in both cases, the classification is now identical to the one of pancreatic cystic tumors.

Tumorigenesis and phenotypic characteristics of mucin-producing bile duct tumors: an immunohistochemical approach

Intraductal papillary neoplasm of the bile duct (IPNB) is characterized by exophytic proliferation of neoplastic epithelial cells with fibrovascular stalks in bile duct lumen, mucin hypersecretion, and considerable dilatation or multilocular changes of the affected bile ducts. A mucin-producing bile duct tumor is an IPNB with excessive mucin production and clinical symptoms. Herein, the phenotypes as well as the tumorigenesis and progression of IPNB are reviewed with immunohistochemical assistance. The tumors are subdivided into three phenotypes: pancreatobiliary, intestinal, and gastric. About half of IPNB cases are of the pancreatobiliary type, and the remaining half are of the intestinal type. Aberrant expression of CDX2 with MUC2 and CK20 is related to the development of intestinal metaplasia. Inactivation of P16INK4a and nuclear expression of beta-catenin are related to the development of IPNB. Decreased expression of membranous beta-catenin and E-cadherin and aberrant expression of MMP-7 and -9 and of MUC1 are related to invasion of IPNB with tubular adenocarcinoma, whereas MUC2 is involved in the invasion of IPNB with mucinous carcinoma. IPNB can be regarded as a counterpart of intraductal papillary mucinous neoplasm (IPMN) of the pancreas, particularly the main duct type. More comparative studies between IPNB and pancreatic IPMN are recommended for further analysis of these papillary neoplasms.

Perihilar cholangiocarcinoma arising in hepatitis C virus-related liver cirrhosis with hepatocellular carcinoma

Liver cirrhosis is reportedly one of the conditions preceding peripheral-type intrahepatic cholangiocarcinoma but not hilar/perihilar cholangiocarcinoma. Herein, we report a case of perihilar cholangiocarcinoma arising in a hepatitis C virus-related cirrhotic liver. The patient was a 69-year-old man. He was diagnosed with hepatitis C virus-related chronic hepatitis at the age of 56 years, and 9 years later, multiple hepatocellular carcinomas were detected by imaging modalities. Despite treatments, including chemotherapy, he died of hepatic failure at the age of 69 years. At autopsy, in addition to multiple nodules of hepatocellular carcinoma, we found a white mucinous and fibrous tumor spreading from the hepatic hilum to the periphery along the left lateral segmental bile ducts in the advanced cirrhotic liver. This tumor was histologically a cholangiocarcinoma that involved mainly the peribiliary glands and showed variable cystic dilation, suggesting that it might have been derived from these peribiliary glands. Immunohistochemically, the cholangiocarcinoma cells were positive for cytokeratin 7 and mucin core protein 1, and negative for cytokeratin 20 and mucin core protein 2. Hilar/perihilar cholangiocarcinoma arising in hepatitis C virus-related liver cirrhosis has rarely been reported. This case warrants further studies to clarify the possible involvement of hepatitis C virus in tumorigenesis of hilar/perihilar cholangiocarcinoma.

Intrahepatic cholangiocarcinoma with multicystic, mucinous appearance and oncocytic change

A case is reported herein of intrahepatic cholangiocarcinoma (ICC) with multicystic, mucinous appearance and oncocytic change. Because of liver dysfunction, a 73-year-old woman was hospitalized in early October 2003. She was diagnosed as having ICC of the right hepatic lobe with occlusion of the hilar and perihilar bile ducts by imaging examination. Extended right lobectomy was performed but the patient died of liver failure on the next day. In surgically resected specimens, the tumor (3 x 3 cm) was mainly located in the right lobe, and tumors infiltrated along the biliary tree as well as invading into the adjacent hepatic parenchyma. The tumor mass had a sponge or honeycomb appearance. Microscopically, these tumors were composed of multiple microcysts filled by abundant mucin and lined by micropapillary adenocarcinoma cells. Their cytoplasm was acidophilic, appearing as an oncocyte, and carcinoma cells were positive for mitochondrial antigen in addition to biliary cytokeratins. There were no ovarian-like stromas around these cystic tumors, and communication of the biliary lumen with these carcinomatous cysts was not evident, thus different from biliary mucinous cystadenocarcinoma and intraductal papillary neoplasm of the liver. This is the third case of multicystic mucinous ICC and the present case might have been derived from intrahepatic peribiliary glands.

Biliary cystic disease

Cystic diseases of the biliary tract encompass a complex group of congenital disorders. Some of the disorders, such as Caroli disease and the hepatobiliary cysts of autosomal-dominant polycystic kidney disease, share common embryologic origins, whereas others, such as choledochal cysts, biliary diverticula, and choledochoceles, have unclear origins. This article reviews the embryologic, clinical, pathologic, and imaging features of biliary cystic disease.

A case report of synchronous double primary liver cancers combined with early gastric cancer

Combined hepatocellular carcinoma and cholangiocarcinoma is found at a frequency of 1.0-6.3% in resected primary hepatic tumors. However, the case of double cancers of hepatocellular carcinoma and cholangiocarcinoma that are discovered synchronously in different lobes of a liver is very rare. We experienced a case of a 74-year-old man who was found to have hepatocellular carcinoma and cholangiocarcinoma in different lobes of the liver, which were accompanied by early gastric cancer. To our knowledge, this is the first case report of double primary hepatic cancers accompanied with early gastric cancer. The pathogenesis and previous related reports of these lesions are discussed.

Clinical outcomes and apomucin expression of intrahepatic cholangiocarcinoma according to gross morphology

BACKGROUND

The clinicopathologic characteristics and the expression of apomucin (MUC) in intrahepatic cholangiocarcinoma (ICC) with respect to gross morphology have not been comprehensively examined.

STUDY DESIGN

We reviewed the clinical data of 98 patients with ICC who underwent resection at Seoul National University Hospital from 1980 to 1998. We also examined the expression profiles of MUC1 and MUC2 in 30 ICC tissues by immunohistochemistry using mouse monoclonal antibodies.

RESULTS

Of 98 cases, 42 were of the mass-forming type of ICC, 22 were of the periductal-infiltrating type, 21 were of the intraductal-growth (IG) type, and 13 were of the mixed type, and the overall 5-year cumulative survival rate was 23.3% in the mass-forming type, 0% in the periductal-infiltrating type, and 76.2% in the IG type. MUC1 was expressed in all types (mass-forming type 75.0%, periductal-infiltrating type 100%, and IG type 73.3%), but significantly, MUC2 was expressed only in the IG type (80.0%), which had better prognosis than the other types.

CONCLUSIONS

It is apparent that the IG type of ICC should be distinguished from the other types of ICC because a favorable prognosis can be expected after complete surgical resection.

Enhanced expression of basement-membrane-type heparan sulfate proteoglycan in tumor fibro-myxoid stroma of intrahepatic cholangiocarcinoma

To investigate the molecular mechanism for enhanced fibrous stroma formation in intrahepatic cholangiocarcinoma (ICC), we surveyed the expression pattern of basement-membrane-type heparan sulfate proteoglycan (HSPG; also known as perlecan) at the core protein and the mRNA level in ICC as well as in other liver neoplasms and reactive hepatic diseases. Immunohistochemistry of paraffin-embedded liver sections with hyaluronidase pretreatment showed that HSPG was present in small amounts in normal liver around the bile ducts and the blood vessels within the portal area. There was no evident expression within the hepatic lobules. Intense immunoexpression of HSPG was seen in the tumor-specific fibro-myxoid stroma of ICC and metastatic liver cancer originating from the colon. However, tumor-specific stroma of hepatocellular carcinomas showed little or no expression of HSPG. At the mRNA level, signals for HSPG were found in tumor cells of cholangiocarcinoma and metastatic colonic carcinomas, and in myofibroblasts in the tumor fibro-myxoid-specific stroma. From immunoprecipitation and reverse transcription-polymerase chain reaction (RT-PCR) analyses, a cultured human intrahepatic cholangiocarcinoma cell line (CCKS1), was found to express high levels of HSPG core protein and mRNA. These findings suggest that biliary and metastatic colon carcinoma cells as well as stromal myofibroblasts have a potential for HSPG production. In order to investigate the growth, invasion and metastatic ability of ICC, further study of the 'self-made' stromal component of ICC may provide a new approach.

Case report: mucinous cholangiocarcinoma featuring a multicystic appearance and periportal collar in imaging

A case of mucinous cholangiocarcinoma (CC), a rare histological type of CC, featuring unusual images is reported. The patient was hospitalized because of acute development of jaundice and fever. Computed tomography demonstrated multiple cystic lesions in the liver and a band-like low density area parallel to the intrahepatic portal vein, a so-called 'periportal collar'. Endoscopic cholangiography revealed a stricture of the hepatic duct with slight upstream dilatation. Cytology of the bile juice and fine-needle aspiration of the cystic lesion in the liver disclosed mucinous carcinoma. The patient died of multiorgan failure 3 weeks after admission. The autopsied liver showed that multiple mucus lakes were lined with adenocarcinoma cells and signet ring cells were floating in the mucus lakes. The cancer cells had spread along the portal tract and invaded into the hepatic parenchyma.

Intrahepatic cholangiocarcinoma arising in congenital hepatic fibrosis: report of an autopsy case

We report an autopsy case of a 60-year-old woman who had congenital hepatic fibrosis with intrahepatic cholangiocarcinoma. A white nodular lesion with a surrounding vague gray area was detected in the right lobe of the liver. Microscopically, most of the nodular lesion was a poorly-differentiated adenocarcinoma. In the surrounding gray area, small bile ducts and bile ductules showed prominent epithelial overgrowth, some of which was composed of dysplasia and well-differentiated adenocarcinoma. The background liver showed the characteristic features of congenital hepatic fibrosis. Immunohistochemically, biliary oncofetal markers (mucin core protein 1 and carcinoembryonic antigen) were more frequently and extensively expressed in poorly-differentiated than well-differentiated adenocarcinoma. This is the 4th reported case of intrahepatic cholangiocarcinoma arising in congenital hepatic fibrosis and suggests that malignant transformation via dysplasia occurs in the abnormal intrahepatic biliary tree of older congenital hepatic fibrosis patients.

Microstructure and development of the normal and pathologic biliary tract in humans, including blood supply

Microstructure and development of the normal biliary tract and the pathologies of several biliary tract diseases in humans are reviewed. The biliary tract, comprising the bile duct and peribiliary glands, is anatomically divided into the extrahepatic and intrahepatic biliary tree. The intrahepatic biliary tree is further divided into large bile ducts, corresponding to the right and left hepatic ducts and their first to third order branches, and into septal and interlobular bile ducts and bile ductules according to their size and location relative to the hepatic lobules and surrounding structures. The right and left hepatic ducts and the extrahepatic bile ducts are composed of dense fibrous duct walls lined by a layer of columnar biliary epithelium. The peribiliary glands, which may secrete mucinous and serous substances into the bile, are found along the extrahepatic and large intrahepatic bile ducts. They are divided in glands within and outside the duct wall. The former (intramural glands) drain directly into the lumen of the bile duct, while the latter (extramural glands) are composed of several lobules and drain into the ductal lumen via their own conduits. The biliary tract is supplied by a complex vasculature called the peribiliary vascular plexus. Afferent vessels of this plexus derive from hepatic arterial branches, and this plexus drains into the portal venous system or directly hepatic sinusoids. The development of the intrahepatic biliary tract is divided into three stages: the stage of the ductal plate, the stage of biliary cell migration into the mesenchyme, and the stage of bile duct formation in the portal tract. It remains unclear how the extrahepatic and intrahepatic biliary tract integrate. Along with these developmental changes in the biliary tract, the peribiliary glands and the vascular plexus also develop in a step-wise manner and their maturation is completed after birth. Pathologies of various biliary diseases are briefly reviewed noting their relevance to several histologic elements and the microenvironment of the biliary tract and the developmental anomalies of the biliary tract including ductal plate malformation.

The surgical challenge of papillary neoplasia of the biliary tract

This study is a case report and literature review of the surgical approach to papillary lesions of the biliary tract exclusive of the ampulla of Vater. Papillary lesions of the bile ducts, exclusive of the ampulla of Vater, are distinctly uncommon but, because of their unpredictable and aggressive behavior, pose challenging problems for the surgeon. Including the present illustrative case description, an English language literature review was conducted to determine the number and clinical behavior of papillary lesions of the bile ducts, particularly the propensity for malignant transformation, and the most favorable surgical approach. In addition to the present case, 29 patients with papillary biliary lesions were found in the literature. Twenty-two patients had tumors in multiple locations in the biliary tract, 6 had isolated lesions in one hepatic duct, and 3 had diffuse papillomatosis. Overall, 15 of 30 patients (50%) died of their disease. Patients with solitary tumors faired best (5 of 6 long-term survivors), and patients with diffuse papillomatosis did worse (all 3 died). Characteristics of these lesions include a propensity for recurrence (15 of 30 patients), an abundant mucin production, and a tendency toward malignant change (eight of 30 patients). Papillary lesions prove difficult to treat because of their frequent multifocality, propensity to recur after surgical extirpation, and malignant potential. Surgical strategy should include liver resection for isolated tumors, close monitoring for recurrence, and reoperations as required to control tumor growth.

A small mucinous cystadenocarcinoma of the liver detected by a fluid-fluid level on ultrasonography

A case of small, borderline malignant biliary mucinous cystic tumor is presented. The patient initially presented to us 18 months earlier to undergo a sigmoid colon resection for sigmoid colon cancer. At that time, a liver cyst measuring 18 x 12 mm was detected. On a follow-up abdominal ultrasonography study for colon cancer, the liver cyst had enlarged to 21 mm in diameter and contained a fluid-fluid level 18 months after surgery. Histological examination of a needle biopsy specimen indicated possible adenocarcinoma. Lateral segmentectomy of the liver was performed. Histopathologically, the tumor was diagnosed as a mucinous cystic tumor, of border line malignancy, which had originated from a bile duct gland. It contained both mucinous and serous components, which were thought to have caused the formation of a fluid-fluid level within the cyst. In this case, the fluid-fluid level demonstrated by ultrasonography was beneficial in the early detection of a cystic tumor of the liver. This case may be the smallest reported cystadenocarcinoma of the liver yet published.

Superficial thrombophlebitis, dysplasia, and cholangiocarcinoma in primary sclerosing cholangitis

Cholangiocarcinoma occurs in approximately 10% of patients with primary sclerosing cholangitis. Usually, liver failure, rapidly progressing jaundice, and an increase in alkaline phosphatase levels are suggestive diagnostic features. We report two cases of patients with primary sclerosing cholangitis who developed cholangiocarcinoma without jaundice and with no changes in their serum biochemistry. Both patients were taking ursodeoxycholic acid at the time of tumor diagnosis. Initial suspicion of malignancy was based on the development of superficial thrombophlebitis. Liver histology showed evidence of bile duct epithelial dysplasia in areas free from tumor in one patient, and in the other, bile duct epithelial dysplasia preceded the appearance of cholangiocarcinoma by at least 18 months. In one of the cases, the dysplastic epithelium stained positively for carcinoembryonic antigen. The histological finding of bile duct epithelial dysplasia in patients with primary sclerosing cholangitis may suggest either imminent or actual development of cholangiocarcinoma and may thus affect consideration of orthotopic liver transplantation. In addition, the development of superficial thrombophlebitis in patients with primary sclerosing cholangitis should arouse suspicion of the presence of cholangiocarcinoma even if there is no evidence of deterioration of the liver function or a dominant stricture on endoscopic retrograde cholangiography.

Intrahepatic peribiliary glands of humans. II. Pathological spectrum

The pathological spectrum of intrahepatic peribiliary glands is reviewed here. Several categories of histopathological changes such as necro-inflammation, cystic dilatation, hyperplasia and neoplasia have been identified in this glandular system. Necro-inflammation is associated with biliary tract diseases and chronic advanced liver diseases and may also appear in the livers of subjects with extrahepatic diseases such as sepsis. Cystic changes of microscopic sizes are not uncommon in autopsy livers of chronic advanced liver diseases, portal hypertensive diseases and also polycystic liver of adult type. Grossly recognizable cysts are, however, infrequent and occasionally cause compression of the adjoining bile ducts. Hyperplasia of these glands, which occurs consistently in hepatolithiasis and more variably in other conditions (e.g. biliary tract infection and submassive hepatic necrosis), may be associated with hypersecretion of seromucinous substances. Hyperplasia of peribiliary glands may then lead to mucin-related biliary diseases. In addition, these glands, particularly the hyperplastic ones, could be a precursor of cholangiocarcinoma. The pathological spectrum of the intrahepatic peribiliary glands is being expanded, although a clinical pathological correlation remains uncharted. Furthermore, age-related variations and non-specific reactive changes of these glands remain unexplored.

Extrahepatic peribiliary glands express alpha-amylase isozymes, trypsin and pancreatic lipase: an immunohistochemical analysis

We examined expression of alpha-amylase isozymes (pancreatic and salivary), trypsin and pancreatic lipase on the epithelium of extrahepatic peribiliary glands immunohistochemically using 53 autopsied normal extrahepatic bile ducts. Three parts of the extrahepatic bile duct (common bile duct, intrapancreatic bile duct and bile duct at the ampulla of Vater) were examined in each case. Histologically, the extrahepatic bile duct harbored branched tubular glands (extrahepatic peribiliary glands). Extrahepatic peribiliary glands were few in the common bile duct and intrapancreatic bile duct and numerous in the bile duct at the ampulla of Vater. Immunohistochemically, pancreatic alpha-amylase was expressed in the epithelium of extrahepatic peribiliary glands in 42 cases (79%). Salivary alpha-amylase was expressed in the epithelium of the glands in 38 cases (72%). Trypsin was expressed in the epithelium of the glands in 32 cases (60%). Pancreatic lipase was expressed in the epithelium of the glands in 45 cases (85%). The immunoreactivity of these enzymes was granular and located in the supranuclear cytoplasm (corresponding to the Golgi apparatus) of the epithelium of the glands. We confirmed the specificity of the immunoreactivity of these enzymes with various methods. These results suggest that extrahepatic peribiliary glands produce alpha-amylase isozymes, trypsin and pancreatic lipase and secrete these enzymes into lumens of the extrahepatic bile duct. The secreted enzymes may play an important role in the physiology of the extrahepatic bile duct and bile.

Expression of alpha-amylase isoenzymes and trypsin by the proliferating epithelium of large intrahepatic bile ducts and intrahepatic peribiliary glands in hepatolithiasis

The expression of alpha-amylase isoenzymes (pancreatic and salivary) and trypsin by the epithelium of large intrahepatic bile ducts and peribiliary glands was examined immunohistochemically in hepatolithiasis (n = 22), extrahepatic biliary obstruction (n = 20) and normal liver (n = 22). Hepatolithiasis was associated with marked proliferation of bile duct cells and peribiliary glands. Expression of pancreatic and salivary amylase was observed in the proliferating bile duct cells and peribiliary glands of all livers, and trypsin was found in 68% of the livers. In extrahepatic biliary obstruction, proliferation of the biliary epithelium was less marked, but expression of amylase isoenzymes was observed in all livers and trypsin was found in 50%. All normal livers showed expression of amylase isoenzymes in large intrahepatic bile ducts, septal bile ducts and peribiliary glands, and trypsin was found in 73%. The density of enzyme-containing acini was highest in hepatolithiasis, intermediate in extrahepatic biliary obstruction and lowest in normal liver. These results show that the proliferating biliary epithelium in hepatolithiasis contains amylase isoenzymes and trypsin and that biliary epithelium retains the ability to produce these enzymes after proliferation, suggesting that a large amount of amylase isoenzyme and trypsin may be secreted into the bile ducts in hepatolithiasis. These enzymes may play an important role in the pathophysiology of hepatolithiasis.

Expression of HLA-DR in intrahepatic cholangiocarcinoma

Expression of HLA-DR was investigated immunohistochemically in 20 cases of intrahepatic cholangiocarcinoma, as well as 9 normal livers that had been obtained at autopsy. Five of the nine normal livers had peribiliary glands that showed HLA-DR. Positive staining for HLA-DR on tumor cells was observed in 6 of 13 cases of cholangiocarcinoma of the hepatic hilus and in only 1 of 7 cases of peripheral cholangiocellular carcinoma. In cholangiocarcinomas of the hepatic hilus, the 5-year survival rate for tumors that had positive staining for HLA-DR was better than that for tumors that had negative staining. Based on these results, the presence or absence of HLA-DR on tumor cells could have a pathologic significance for intrahepatic cholangiocarcinoma.

Cystic dilatation of peribiliary glands in livers with adult polycystic disease and livers with solitary nonparasitic cysts: an autopsy study

Cystic dilatation of peribiliary glands of intrahepatic and extrahepatic bile ducts was investigated in autopsied livers with adult polycystic disease (n = 8), in autopsied livers with solitary nonparasitic cysts (n = 18) and in normal autopsied livers (n = 23). In normal livers, cystic dilatation of intrahepatic peribiliary glands was absent or slight, when present. In livers with solitary nonparasitic cysts, cystic dilatation of intrahepatic peribiliary glands was present in varying degrees. In livers with adult polycystic disease, intrahepatic peribiliary glands showed frequent and severe cystic dilatation so marked that it was grossly recognizable. In contrast, peribiliary glands of the extrahepatic bile ducts showed no cystic dilatation in most cases, regardless of the three conditions examined. Liver parenchymal cysts were numerous in livers with adult polycystic disease, few in livers with solitary nonparasitic cysts and nonexistent in normal livers. Von Meyenburg complexes were present in 87.5% of livers with adult polycystic disease, in 16.7% of livers with solitary nonparasitic cysts and in 4.3% of normal livers. These findings suggest that intrahepatic peribiliary glands undergo cystic dilatation in livers with adult polycystic disease-and, to a lesser degree and frequency in livers with solitary nonparasitic cysts, probably because of congenital or genetic factors-and that these cystic changes may comprise a part of numerous cysts of adult polycystic disease.

Pathologic observations of intrahepatic peribiliary glands in 1,000 consecutive autopsy livers: IV. Hyperplasia of intramural and extramural glands

Hyperplastic changes of intrahepatic peribiliary glands have rarely been reported, with the exception of hepatolithiasis. To determine whether there are any hyperplastic changes in the glands in livers without hepatolithiasis, we examined 1,000 consecutive autopsy liver specimens that had no hepatolithiasis. The glands were divided into intramural mucous glands and extramural seromucous glands. The hyperplastic changes were found in "normal" livers and in livers with various hepatobiliary diseases, and they were classified into three categories: hyperplasia of intramural glands (49 cases; 4.9%), hyperplasia of extramural serous acini (35 cases; 3.5%), and hyperplasia of extramural mucous acini (92 cases; 9.2%). Two or more of these three hyperplastic changes occasionally coexisted in the same liver. Hyperplasia of intramural glands was seen rather evenly in normal livers and in livers with various hepatobiliary diseases. Prevalence of hyperplasia of extramural serous acini was high in intrahepatic cholangitis and submassive hepatic necrosis. Prevalence of hyperplasia of extramural mucous acini was high in cirrhosis, submassive hepatic necrosis, cholangitis, systemic infection, and extrahepatic biliary obstruction. The hyperplastic intramural glands and mucous acini of extramural glands contained more neutral, carboxylated, and sulfated mucin than normal glands. Although their pathogenesis is unclear, these hyperplastic changes may enhance seromucous secretion into biliary lumens and may lead to biliary dysfunctions such as retardation of bile flow and increased bile viscosity. These hyperplastic changes may be preexisting conditions predisposing to hepatolithiasis.

The stem cells of the liver ? a selective review

The current status of the much-debated question of the still-hypothetical stem cells of the liver is reviewed, with an emphasis on their role in hepatocarcinogenesis. The widely held view of the primacy of the hepatocyte, notably of the mononuclear diploid type, in this process--the "hepatocytic theory"--has been compared with variants of the "stem cell hypothesis" based on the "non-parenchymal epithelial cells" of the liver--the "oval" or biliary ductular cells, the "nondescript periductular" cells and the "primitive" bipotential epithelial cells. An attempt has been made to concentrate mainly on the more recent publications, in an effort to balance the conflicting opinions expressed by comparing results obtained by the newer procedures currently in use. Despite some interesting and relevant findings it appears that the evidence in favour of the stem-cell hypothesis is still circumstantial and that the hepatocytic theory has not been invalidated. Presumably the question of the hepatic stem cells will be answered when the riddle of hepatocarcinogenesis has been solved.

Immunohistochemical demonstration of pancreatic alpha-amylase and trypsin in intrahepatic bile ducts and peribiliary glands

Epithelia of intrahepatic bile ducts and peribiliary glands were immunohistochemically examined for pancreatic alpha-amylase and trypsin in 54 normal autopsied livers. alpha-Amylase was evaluated with a polyclonal antibody, and trypsin was assayed with both polyclonal and monoclonal antibodies. alpha-Amylase was observed in large ducts, septal ducts and peribiliary glands in most livers and was seen in interlobular ducts in seven (13%) livers. Trypsin immunoreactivity with the polyclonal antibody was observed in peribiliary glands in 21 (39%) livers; it was absent in intrahepatic bile ducts in all but one liver. Trypsin immunoreactivity with the monoclonal antibody was present in large ducts, septal ducts and peribiliary glands in about 70% of the livers and was seen in interlobular ducts in two (4%) livers. Bile ductules were always negative for the two antigens. Some epithelia of peribiliary glands positive for both alpha-amylase and trypsin histologically resembled pancreatic acinar cells. alpha-Amylase and trypsin immunoreactivities of intrahepatic biliary epithelia and pancreatic aninar cells were eliminated by absorption of primary antibodies by alpha-amylase or trypsin, suggesting the specificities of the immunoreactivities. These data suggest that epithelia of intrahepatic large ducts, septal ducts and peribiliary glands contain pancreatic alpha-amylase in most livers and that they contain trypsin in about 70% of livers. alpha-Amylase and trypsin may be secreted into intrahepatic bile duct lumens, thereby exerting important effects on the physiology of the intrahepatic biliary tree and hepatic bile.

Interactions between epithelial and mesenchymal cells in intrahepatic peribiliary glands in normal and hepatolithiatic livers

The anatomy and pathology of the intrahepatic peribiliary glands were evaluated. In this study, we ultrastructuraly examined the peribiliary glands of normal and hepatolithiatic livers using common and serial ultrathin section observations. It is well known that these glands proliferate markedly in hepatolithiasis. These glands were composed of several acini surrounded by thickened and multilayered basement membranes, and there were mesenchymal cells (the majority were fibroblasts) in the periacinar fibrous connective tissue. Some cytoplasmic processes of acinar epithelial cells and mesenchymal cells in the periacinar connective tissue were in close contact with each other within the thickened and multilayered basement membranes. Such cell-to-cell interaction was most frequent in cases of hepatolithiasis, in which peribiliary glands proliferated markedly. In hepatolithiatic livers, some unmyelinated nerve fibers or axonal button profiles were in close contact with periacinar mesenchymal cells and also with cytoplasmic processes of glandular epithelial cells. Such contacts were rare in normal livers. These findings suggest that such epithelial and mesenchymal cell interactions and innervations play a part in the normal regulation of peribiliary glands and also in the proliferation of peribiliary glands in hepatolithiasis.

Pathological observations of intrahepatic peribiliary glands in 1,000 consecutive autopsy livers. III. Survey of necroinflammation and cystic dilatation

Pathological changes and significance of intrahepatic peribiliary glands, hitherto poorly recognized intrahepatic elements, have been evaluated in our laboratory. In this report, we surveyed necroinflammatory and cystic changes of the peribiliary glands in 1,000 consecutive autopsy livers because these two changes coexisted frequently in the same liver. The necroinflammatory change was found in 228 livers (22.8%) and the cystic change in 202 livers (20.2%), and 103 cases showed both changes in the same liver. The necroinflammatory change was frequently found in intrahepatic cholangitis and extrahepatic biliary obstruction with bacterial infection, suggesting that biliary bacterial inflammation extends into these peribilary glands. This change was also frequent in systemic infection or septicemia without biliary bacterial infection, implying that the peribiliary glands were also damaged in such conditions without direct infection. The cystic change was frequent in livers with portal hypertension or obstruction, adult polycystic disease and necroinflammation of the glands, suggesting that the cystic change of the glands could occur as the result of the disturbance of intrahepatic circulation or as the result of inflammatory destruction of the glandular conduits. Some of peribiliary cysts may be of congenital origin. Dysfunction related to these pathological changes in the glands may diminish seromucous secretion and cause alterations in hepatic bile composition. The cystic change of the glands may retard bile flow by compressing bile duct lumina.

Amyloid deposition in intrahepatic large bile ducts and peribiliary glands in systemic amyloidosis

Amyloid deposition in the hepatic parenchyma and portal tracts in the liver is well known in systemic amyloidosis. We recently experienced an autopsy case of systemic amyloidosis presenting the amyloid deposits in the intrahepatic biliary tree. This experience prompted us to survey 19 autopsy cases of systemic amyloidosis. Amyloid deposition was found just under the lining epithelium of the intrahepatic large bile duct in 10 of 19 cases and around the peribiliary glandular acini in 7 of the 19 cases, respectively. Amyloid deposition in the intrahepatic large bile duct and peribiliary glands was positively correlated with the degree of amyloid deposition in the liver but not with type of amyloid protein. Double-staining of amyloid and vascular endothelium disclosed that amyloid deposition was more closely related to the inner part of the peribiliary vascular plexus and to the vascular plexus encircling the peribiliary glands than the lining biliary epithelium and peribiliary glandular acinar cells themselves. The exact pathogenesis of amyloid deposition in these anatomical components, however, remains unclear. Although our cases failed to show any overt clinical symptomatologies related to amyloid deposition in these biliary components, it seems conceivable that more massive amyloid deposition in these anatomical components could give rise to some clinical symptoms.