Cytokeratin profile relates to histological subtypes and intrahepatic location of intrahepatic cholangiocarcinoma and primary sites of metastatic adenocarcinoma of liver

AIMS: We evaluated the cytokeratin profile of intrahepatic cholangiocarcinoma with respect to its histological classification and intrahepatic location (peripheral vs. hilar), and compared its profile with that of a variety of metastatic adenocarcinomas in liver. METHODS AND RESULTS: Expression of cytokeratins 7, 8, 18, 19 and 20 was immunohistochemically examined in intrahepatic cholangiocarcinoma (n = 77) and metastatic adenocarcinoma in liver (21 colorectal, 14 gastric, three gallbladder and three pancreatic cancers). Materials were autopsy or surgical specimens. Cytokeratins 7, 8, 18 and 19 were expressed in 75 (97%), 75 (97%), 59 (77%) and 71 (92%) cases of intrahepatic cholangiocarcinoma, respectively. Moderate and extensive expression of cytokeratin 18 was more frequent in the peripheral than in the hilar type. Moderate and extensive expression of cytokeratin 19 was seen in almost all cases of well-differentiated intrahepatic cholangiocarcinomas, while expression was decreased relatively in the moderately and decreased more in the poorly differentiated cases. While cytokeratin 20 was not found in non-neoplastic biliary epithelia or in well-differentiated intrahepatic cholangiocarcinomas, this cytokeratin was occasionally detectable in moderately and poorly differentiated intrahepatic cholangiocarcinomas and its expression was more frequent in the hilar type. Cytokeratin 20 expression was observed in 17 (81%) of metastatic adenocarcinomas in liver from colorectal regions, to a lesser degree in those from gastric regions, and was rare in those from gallbladder and pancreatic regions; cytokeratin 7 showed a reverse expression pattern in these metastatic adenocarcinomas in liver. The profile of cytokeratins 7 and 20 of metastatic colorectal and gastric carcinomas differed from that for intrahepatic cholangiocarcinomas, while that of metastatic gallbladder and pancreatic carcinoma was similar to that for intrahepatic cholangiocarcinomas. Moreover, cytokeratin 18 and 19 expression was significantly infrequent in metastatic gastric carcinomas than in intrahepatic cholangiocarcinomas and metastatic colorectal carcinomas. CONCLUSION: The combined immunostaining of cytokeratins 7, 18, 19 and 20 is useful for the characterization of intrahepatic cholangiocarcinomas with respect to histological subtypes and intrahepatic location. It helps to differentiate intrahepatic cholangiocarcinoma from metastatic adenocarcinomas in liver and from colorectal and gastric regions; it also indicates the primary focus metastatic adenocarcinomas in livers.     

Distribution patterns of cytokeratin antigen determinants in alcoholic and nonalcoholic liver diseases

Aggregation and derangement of cytokeratin intermediate filaments are thought to be the key mechanism in the formation of Mallory bodies in alcoholic liver disease (ALD). To study the incidence and patterns of intracellular distribution of aggregated cytokeratin and to determine its utility as a diagnostic marker of ALD, 108 liver biopsy specimens from patients with various liver abnormalities were examined by an avidin--biotin peroxidase complex technique on paraffin section using a monoclonal antibody to cytokeratins (Hybritech). In normal liver (n = 11), only bile duct epithelium was positive. Both bile ducts and hepatocytes were positive in pathologic livers (n = 97). In ALD, 82 per cent of cases (42 of 51) showed cytokeratin positivity versus 15 per cent (seven of 46) in nonalcoholic liver disease (e.g., chronic hepatitis, nonalcoholic cirrhosis, cholestasis, and primary biliary cirrhosis). The highest incidence (100 per cent, 37 of 37) of positivity was obtained in cases with alcoholic hepatitis and cirrhosis compared with only 36 per cent (five of 14) in alcoholic fatty liver. Mallory bodies were found by the immunoperoxidase method in 71 per cent of cases (30 of 42) versus in 40 per cent (17 cases) by hematoxylin--eosin stain. In alcoholic fatty liver and alcoholic hepatitis, centrilobular hepatocytes showed cytokeratin positivity, whereas such reactivity was seen predominantly at the periphery of the regenerative nodules in alcoholic cirrhosis. A rare periportal hepatocyte was positive in the nonalcoholic group. These findings suggest that the differential distribution patterns of aggregated cytokeratin may be helpful in differentiating alcoholic from nonalcoholic liver diseases.     

Expression of tissue polypeptide antigen (TPA) in fetal and adult liver: changes in liver disease.

The distribution of tissue polypeptide antigen (40 kD molecular weight) in normal adult and fetal liver, and in liver disease was investigated and compared with the distribution of low and high molecular weight cytokeratins. In normal liver tissue polypeptide antigen was found only in bile duct epithelium; this distribution is similar to that of high molecular weight cytokeratin, but differs from that of low molecular weight cytokeratins. In liver disease it was found in areas of ductular transformation; in Mallory's bodies; and in alcoholic liver disease and primary biliary cirrhosis in some hepatocytes that did not contain Mallory's bodies.     

Immunohistochemical detection of bcl-2 protein in normal and pathological human liver.

The bcl-2 protein, which prolongs cell survival by blocking apoptosis, is expressed by progenitor cells in several self-renewing tissues and by tumoral cells in some extrahepatic neoplasms. Because the liver is a slow self-renewing tissue, an immunohistochemical study of the cellular distribution of the bcl-2 protein was performed in normal liver (12 cases), nontumoral hepatic lesions (33 cases), and benign or malignant liver tumors (46 cases). In normal liver, bcl-2 was expressed by bile ductules and small bile duct epithelium, but not by hepatocytes or large bile duct epithelium. In cirrhosis and focal nodular hyperplasia, epithelial cells of the ductular proliferation were bcl-2-positive. Eight of 11 cholangiocarcinomas stained positively for bcl-2, whereas all 15 hepatocellular carcinomas were bcl-2-negative. bcl-2 was also expressed in 6 of 14 metastatic adenocarcinomas. These findings suggest that the ductular cells and small bile duct epithelial cells might have a prolonged survival and might be hepatic progenitor cells. In addition, the bcl-2 protein appears to be a marker of cholangiocarcinoma but not of hepatocellular carcinoma and could help in distinguishing between these two primary liver tumors.     

Cytokeratin intermediate filament expression in benign and malignant breast disease.

AIM--To carry out a comprehensive study of cytokeratin expression in benign and malignant breast epithelium and breast myoepithelial cells; to examine changes in the cytokeratin profile in malignant and benign epithelium and in carcinomas of increasing histological grade. METHODS--Frozen sections from fibroadenomas (19 cases), fibrocystic disease (19 cases), and infiltrating ductal (68 cases), lobular (seven cases), and mucinous carcinomas (three cases) were examined using a panel of monoclonal antibodies. RESULTS--The luminal epithelium in all fibroadenomas and all cases of fibrocystic disease, as well as tumour cells in most carcinomas, reacted with the specific antibodies to cytokeratins 7, 8, 18, and 19 and to antibodies which included these cytokeratins in their specificities (Cam 5.2, AE1, AE3, RCK102, and LP34). In a few ductal carcinomas none of the tumour cells reacted for cytokeratins 7, 8, or 18. Three ductal carcinomas expressed cytokeratin 14. Only occasional cases expressed cytokeratins 3, 4, 10, and 13. Antibodies which included cytokeratins 5 and 14 in their specificities detected myoepithelial cells less efficiently than antiactin antibodies. CONCLUSION--The cytokeratin profiles in the luminal epithelium in benign breast disease and in tumour cells in most carcinomas are similar in most cases. Some carcinomas, however, are negative for cytokeratins 7, 8, or 18. This may provide a means of predicting the biological behaviour of a histologically borderline lesion.     

A cytokeratin-immunohistochemical study of hepatoblastoma.

Six cases of hepatoblastoma (five epithelial, one mixed epithelial-mesenchymal) were studied on serially cut cryostat sections, using a panel of monoclonal antibodies directed against individual cytokeratins, vimentin, and desmin, in an indirect immunoperoxidase procedure. Embryonic and fetal-type tumor cells expressed the "hepatocellular" cytokeratins no. 8 and 18 but, surprisingly, also expressed the "bile duct type" cytokeratin no. 19. In addition, two cases had a number of tumor cells which were also positive for the "bile duct type" cytokeratin no. 7. Cells embedded in osteoid-like material were immunoreactive for vimentin but also for cytokeratins no. 7, 18, and 19. Gel electrophoresis, and Western blotting of cytoskeletal extracts, confirmed the immunohistochemical data. The implications of these findings for the histogenesis of hepatoblastoma are discussed in this report.     

A cytokeratin immunohistochemical study of alcoholic liver disease: evidence that hepatocytes can express ''bile duct-type'' cytokeratins

A cytokeratin immunohistochemical study was performed on 40 liver biopsies diagnosed as alcoholic liver disease to further investigate the cytoskeletal changes occurring in this disease. On paraffin sections of 29 cases, a variable number of hepatocytes were reactive with a polyclonal antiserum that normally stains only bile ducts. Using monoclonal antibodies specific for a single cytokeratin polypeptide on cryostat sections, a variable number of hepatocytes were immunoreactive for cytokeratin no. 7 in 23 cases and also for cytokeratin no. 19 in seven cases. Both these polypeptides are restricted to bile duct cells in the normal liver. The number of hepatocytes positive for bile duct-type cytokeratins increased and their location changed with the severity of the disease. Mallory bodies were reactive with monoclonal antibodies CAM 5.2 and anti-cytokeratin no. 18 but unreactive with anti-cytokeratin no. 8. except in one case. In two cases, Mallory bodies reactive with both monoclonal antibodies anti-cytokeratin no. 7 and anti-cytokeratin no. 19 were found. These results clearly indicate that hepatocytes in alcoholic liver disease can express immunoreactivity for bile duct-type cytokeratins. Our data also demonstrate heterogeneity in the composition of Mallory bodies. Whether hepatocytes expressing bile duct-type cytokeratins are the precursors of Mallory body-containing cells is not clear at present.     

Distinction between hepatocellular carcinoma, cholangiocarcinoma, and metastatic carcinoma based on immunohistochemical staining for carcinoembryonic antigen and for cytokeratin 19 on paraffin sections

An antiserum to carcinoembryonic antigen (CEA) and a monoclonal antibody to cytokeratin 19 (CK 19) were studied for their suitability as diagnostic reagents for the differential diagnosis of primary and secondary malignant epithelial tumours of the liver, on paraffin sections. With the antiserum to CEA, positive bile canalicular structures were found in 60 per cent of the hepatocellular carcinomas. All the cholangiocarcinomas and 66.6 per cent of the metastatic carcinomas were positive for CEA, without displaying a canalicular staining pattern. All the hepatocellular carcinomas were negative for CK 19. All the cholangiocellular carcinomas and the metastatic carcinomas were positive for CK 19. This staining profile may prove helpful in difficult diagnostic cases.     

Cytokeratin expression in hepatocellular carcinoma: an immunohistochemical study

Normal human hepatocytes express cytokeratins no. 8 and 18, whereas bile duct cells contain the same cytokeratins and, in addition, cytokeratins no. 7 and 19. This cytokeratin pattern is believed to be preserved during neoplastic transformation. Thirty-four cases of hepatocellular carcinoma (11 well differentiated, 16 moderately differentiated, 7 poorly differentiated) were studied on frozen sections using monoclonal antisera directed against individual cytokeratins no. 7, 8, 18, and 19 in an immunoperoxidase procedure. In 17 of 34 cases, tumor cells showed only reactivity with monoclonals anticytokeratin no. 8 and 18. However, 17 of 34 cases showed an aberrant pattern in that a variable number of tumor cells were stained with anticytokeratins no. 7 and/or 19 in addition to no. 8 and 18. Only three of 11 well-differentiated cases displayed an unexpected cytokeratin pattern, whereas an aberrant pattern was present in all seven of seven poorly differentiated cases. These results are in conflict with previously published data obtained by two-dimensional gel electrophoresis and immunohistochemistry. They indicate that the cytokeratin pattern might not always be preserved during neoplastic transformation. The implication of this finding for the differential diagnosis of metastatic gastrointestinal carcinomas is discussed.     

The distribution of cytokeratin antigens in the kidney and in renal tumours

The distribution of cytokeratin antigens during embryogenesis of the kidney and in 57 renal tumours has been studied using immunocytochemical techniques. A polyclonal antiserum to epidermal prekeratins and the monoclonal antibodies CAM 5.2 and PKK1 have been used to identify cytokeratins of different molecular weights. The ureteric bud-derived structures expressed large molecular weight cytokeratins. The tubular component of the kidney expressed cytokeratins detected by CAM 5.2 and PKK1. During glomerular development there was transient expression of low molecular weight cytokeratins by the visceral glomerular epithelium but in the adult kidney only the parietal epithelium expressed cytokeratins. Tubules in nephroblastomas contained low molecular weight cytokeratins but the blastema did not. Some ureteric bud-derived structures were identified in six nephroblastomas. Renal carcinomas expressed low molecular weight cytokeratins. Four collecting duct carcinomas were studied; these all expressed the large molecular weight cytokeratins found in collecting duct epithelium. These results indicate that the cytokeratin phenotype of renal tumours is unchanged from that of the normal epithelial cells.     

Expression of cytokeratin 7 and 20 in pathological conditions of the bile tract

Expression of cytokeratin 7 (CK7) and cytokeratin 20 (CK20) helps to establish the origin of biliary and metastatic carcinomas. We investigated the expression of CK7 and CK20 in inflammatory, metaplastic and neoplastic conditions of the bile ducts, and evaluated possible relationships between the CK expression pattern and extrahepatic bile duct/gallbladder carcinomas (EBDCs) or intrahepatic bile duct carcinomas (IBDCs). We used immunohistochemistry for the investigation of 48 formalin-fixed, paraffin-embedded specimens grouped as: A) lithiasic or inflamed surgically resected extrahepatic bile ducts/gallbladders: all were CK7+/CK20+; B) percutaneous liver biopsies from patients with chronic hepatitis C primary biliary cirrhosis and primary sclerosing cholangitis: all were CK7+/CK20-; C) EBDCs: all were CK7+/CK20+, except for two cases which were CK7-/CK20-; D) IBDCs: all were CK7+/CK20-, except for one case showing CK20 positivity. Metaplastic changes were seen only among specimens in groups A and C: in these cases, CK20 was either focally or diffusely expressed. Our study suggests that the expression of cytokeratins under specific stimuli can be different from normal tissues, and that sometimes CK20 expression can be related to and precede the occurrence of metaplastic alterations.     

Distribution of TPA and cytokeratins in gastrointestinal carcinomas as revealed by immunohistochemistry

Summary The presence and distribution of tissue polypeptide antigen (TPA) were assessed in gastrointestinal carcinomas of different origin, morphology and degree of differentiation. Immunocytochemistry was employed, using the PAP technique on formalin-fixed, paraffin-embedded material and compared with the results obtained with antibodies to cytokeratins. Like cytokeratins, TPA was a reliable marker of epithelial differentiation and showed tissue distribution patterns similar to cytokeratins, as revealed by antibodies with broad-range cytokeratin immunoreactivity. In most carcinomas, TPA-specific immunostaining was less intense than in non-neoplastic tissue. No direct relationship between intensity of TPA staining and morphological degree of differentiation and proliferation was found. TPA staining was most pronounced at the periphery of the cells. In stratified epithelium, i.e. oesophageal mucosa, basally located cells exceeded superficial cells in TPA immunoreactivity in contrast to the cytokeratin antibodies which decorated the more superficially placed cell layers. TPA and cytokeratin staining patterns were similar in neoplastic and non-neoplastic gastric, intestinal mucosa, as well as in biliary tract epithelium. Antral and cardial mucoid glands of the stomach as well as gastric carcinomas of the pylorocardial type remained unstained with both types of antibodies. Similar staining with TPA and cytokeratin antibodies was also observed in pancreatic and liver tissue. In this study, hepatocytes were, although weakly, stained by TPA antibodies and an identical staining was found with benign and malignant hepatocellular neoplasms. Ductal and ductular TPA-staining was most conspicuous and so was the immunoreactivity of cholangiocellular carcinomas. A comparison between TPA and cytokeratins was also made by immunoblotting which revealed immunoreactivity of antibodies to TPA with cytokeratin polypeptides of different species (man, mouse) and organs (epidermis, liver), particularly with the cytokeratin component 8 of human liver and the related component A of mouse liver. The significance of this finding is uncertain until the pertinent epitopes have been revealed by monoclonal mapping of the components which exhibit similar molecular weights by SDS polyacrylamide gel electrophoresis.     

Characterization of ductular hepatocytes in end-stage cirrhosis

The existence of facultative stem cells in the liver has been advocated based on observations from models of carcinogenesis in rat liver. Observations of human liver material from cases of fulminant hepatitis have shown the presence of ductular hepatocytes expressing markers of both hepatocytes and bile duct cells. We describe the morphologic features and antigenic expression of a population of ductular hepatocytes identified in a patient with end-stage cirrhosis resulting from hepatitis B infection and secondary biliary cirrhosis. By conventional light microscopy and electron microscopy, ductular hepatocytes were seen to form pseudoductules within periportal areas. Using immunohistochemical methods, these ductular hepatocytes were found to be positive for both the hepatitis B surface antigen and bile duct epithelial cytokeratin, phenotypic markers classically restricted to expression on hepatocytes and bile duct epithelium, respectively. These findings show definitively that ductular hepatocytes are intermediate cells bearing morphologic and phenotypic characteristics of both hepatocytes and bile duct epithelium. The presence of these cells indicates the existence of facultative stem cells in the adult mammalian liver.     

Immunohistochemical detection of breast specific antigens and cytokeratins in metastatic breast carcinoma in the liver

The present study was performed to evaluate the diagnostic reliability of antibodies to breast carcinoma-specific antigen and antibodies to cytokeratin catalogue in a metastatic hepatic lesion. Immunohistochemical examinations using antibodies to gross cystic disease fluid protein-15 (GCDFP-15), BCA-225 (a glycoprotein secreted by T47D breast carcinoma cell line) and BRST-5 (a glycoprotein identified in SK-BR-7 breast carcinoma cell line), anti-cytokeratin monoclonal antibodies of MA904, AE3, CAM5.2, PKK1 and cytokeratin 19, and polyclonal anti-keratin antibodies were done. These were on 15 cases of primary breast carcinoma, eight cases of metastatic breast carcinoma in the liver, five cases of cholangiocarcinoma, eight cases of hepatocellular carcinoma and 11 cases of metastatic adenocarcinoma of another primary tumor in the liver. Results showed that GCDFP-15 antigen was most reliable: it was 100% positive in both primary and metastatic breast carcinomas unrelated to histological subtypes, and 100% negative in primary or other metastatic carcinomas in the liver. BCA-225 antigen was detected in high amounts in breast carcinomas (100%, 23/23), but it was positive in cholangiocarcinomas (80%, 4/5) and another metastatic carcinoma in the liver (64%, 7/11). BRST-5 was specifically positive in breast carcinomas but the positivity was low (13%, 3/23). Cytokeratin 19 and keratin were useful to discriminate hepatocellular carcinomas (0%, 0/8) from breast carcinomas (87%, 20/23; 96%, 22/23), but they were also positive in cholangiocarcinomas (100%, 5/5) and other metastatic carcinomas in the liver (91%, 10/11). AE3, CAM5.2 and PKK1 showed highly positive immunoreactivity for breast carcinomas, cholangiocarcinomas and other metastatic carcinomas in the liver, and hepatocellular carcinoma cells were sometimes stained (50%, 4/8; 88%, 7/8; 38%, 3/8). MA904 showed negative immunoreactivity for all cases examined. A discussion was made on the specificity of the antibodies available for a histologic differential diagnosis.     

The utility of keratin 903 as a new prognostic marker in mass-forming-type intrahepatic cholangiocarcinoma.

The cytokeratins phenotype is largely preserved during neoplastic transformation and tumor development. We evaluated the immunoreactivity of biliary epithelial markers keratin 903 and cytokeratin 7 and 19 for intrahepatic cholangiocarcinoma, and compared the results with those for biliary dysplasia and hepatocellular carcinoma. Reactivity with keratin 903 was weakly expressed and increased after the expression of cytokeratin 7 and 19 during human intrahepatic bile duct development. More than 80% of cases of biliary dysplasia showed positive reactivity with keratin 903. Of the 30 cases of hepatocellular carcinoma, 3 (10%), 6 (20%), and 1 (3%) showed positive reactivity with Keratin 903 and cytokeratin 7 and 19, respectively. Among the 73 cases of intrahepatic cholangiocarcinoma, 54 (74%), 66 (90%), and 61 (84%) showed positive reactivity with keratin 903 and cytokeratin 7 and 19, respectively. On clinicopathologic examination of intrahepatic cholangiocarcinomas, reduced keratin 903 reactivity was significantly higher in tumors with an expansive growth pattern (P <.0001), in those with medullary-type stromal reaction (P =.0327), in those without perineural invasion (P =.0001), and in those without lymph node metastasis (P =.0015). In addition, the reactivity with Keratin 903 was directly correlated with expression of cytokeratin 7 and 19 (P =.0153 and P <.0001, respectively). Cases showing reduced keratin 903 reactivity were characterized by a distinctive morphology indicating an hepatocellular carcinoma-like pattern. Multivariate analysis of overall survival revealed that keratin 903 reactivity was a significantly independent prognostic factor. In conclusion, patients with intrahepatic cholangiocarcinoma showing reduced keratin 903 reactivity had a favorable prognosis. Remarkably, the cytokeratin phenotype of intrahepatic cholangiocarcinoma was correlated with the morphologic appearance of intrahepatic cholangiocarcinoma.     

Claudins and tricellulin in fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma is a subtype of hepatocellular carcinoma occurring in non-cirrhotic liver at a younger age. The tumor expresses both hepatocellular and cholangiocellular markers. Previously, our group described overexpression of tight junction protein claudin 4 in cholangiocellular carcinoma in contrast to hepatocellular carcinoma. In the present study, tight junction protein expressions were studied to possibly clarify bipotential lineage of fibrolamellar hepatocellular carcinoma. Eleven fibrolamellar hepatocellular carcinomas were compared with seven “conventional” hepatocellular carcinomas, seven cholangiocellular carcinomas, and five normal liver samples. By immunohistochemistry, all fibrolamellar hepatocellular carcinomas were positive for HepPar1 and cytokeratins 7, 8, and 18, but negative for cytokeratin 19. Glypican-3 gave weak staining in two cases. Expression of claudin 1 was lower, while that of claudin 2 was higher in fibrolamellar hepatocellular carcinomas than in other tumors. Claudins 3, 4, and 7 were not detectable in fibrolamellar hepatocellular carcinomas as in the majority of “conventional” hepatocellular carcinomas, contrary to high expression observed in cholangiocellular carcinomas. Focal or diffuse claudin 5 expression was detected in nine of 11 fibrolamellar hepatocellular carcinomas contrary to other tumors. Tricellulin was significantly downregulated in all tumors compared with normal liver. Our findings showed claudins to exhibit specific expression patterns in fibrolamellar hepatocellular carcinomas not observed in other primary liver tumors, with unique claudin 5 expression and pattern features similar to common hepatocellular carcinoma, but different from cholangiocellular carcinoma. This is the first report describing the loss of tricellulin expression in human hepatic tumors.     

De novo expression of nonhepatocellular cytokeratins in Mallory body formation

 Mallory bodies (MBs) are eosinophilic cytoplasmic inclusions observed predominantly in alcoholic liver disease. Although linked to disease activity, their pathogenesis is still unclear. Since intermediate filaments (cytokeratins) are major components of MBs, their cytokeratin polypeptide composition was analysed with monospecific antibodies for cytokeratins 7, 8, 14, 18, 19, and 20 by immunohistology. MBs were identified by light microscopy and ubiquitin immunostaining. All MBs were positive for cytokeratins 8 and 18. A significant percentage of the MBs was strongly positive for cytokeratins 19 and/or 20, which are not detectable in hepatocytes of normal liver and, in the case of cytokeratin 20, in hepatocytes of diseases devoid of MBs. MBs were essentially negative for cytokeratins 7 and 14. De novo expression of cytokeratins 19 and 20 was independent of the aetiology, occurring in all MB-associated diseases analysed, and seemed to precede MB formation, since in some hepatocytes a cytoskeletal-type staining pattern for these cytokeratins was present. In hepatocellular carcinomas cytokeratins 19 and 20 were frequently detected, but their cellular distribution was less closely associated with MBs. The ectopic expression of cytokeratins 19 and 20 appears to be related to MB formation and may take part in the derangement of the intermediate filaments during MB formation. Received: 21 May 1997 / Accepted: 10 September 1997     

Tissue polypeptide antigen--a marker antigen differentiating cholangiolar tumors from other hepatic tumors

Twenty-two cases of primary hepatic tumors consisting of 11 hepatocellular carcinomas, 6 cholangiocarcinomas, 3 mixed hepatocellular and cholangiocellular carcinomas, and 2 biliary cystadenocarcinomas together with 8 cases of metastatic adenocarcinoma from various sites were studied by immunoperoxidase technic to demonstrate tissue polypeptide antigen. All of the tumors presumably derived from the epithelial lining of the bile duct, including cholangiocarcinoma, cholangiocarcinomatous portion of the mixed hepatocellular and cholangiocellular carcinoma, and biliary cystadenocarcinoma showed strong positive reaction. The hepatocellular carcinoma and the metastatic adenocarcinoma exhibited negative to weakly positive reactions. These results indicate that TPA can be of use in differentiating bile duct carcinomas from hepatocellular carcinoma and, to a lesser extent, from hepatic metastases of various adenocarcinomas.     

Cytokeratin expression in cells of the rodent bile duct developing under normal and pathological conditions

A polyclonal anti-cytokeratin antibody has been used to examine the expression of this intermediate filament both during normal development in the rat and in a variety of pathological states in the rat and mouse. Bile duct proliferation induced by the administration of alpha-naphthylisothiocyanate (ANIT) as well as the oval cell proliferation induced by 3'-methyl-4-dimethylaminoazobenzene (3-MeDAB) have been used to examine the expression of the rodent cytokeratins in the proliferating cells regarded as being of bile duct origin. Examples of cholangiofibrosis and cholangiocarcinomas were also examined for evidence of cytokeratin expression using this antibody, as well as proliferations of a morphological intermediate type between epithelial and mesenchymal. In all cases we have been able to demonstrate continuity of phenotypic expression of the cytokeratins recognized by this antibody in cells which are recognized as bile duct in origin, even where their morphological appearance does not resemble an epithelial cell type. Because this antibody can be used on formalin-fixed, paraffin-processed tissues, after trypsin treatment, it is proposed that it can be used routinely in the toxicological evaluation (even retrospectively) of bile duct related proliferations and tumours.     

Cytokeratin expression in cells of the rodent bile duct developing under normal and pathological conditions.

A polyclonal anti-cytokeratin antibody has been used to examine the expression of this intermediate filament both during normal development in the rat and in a variety of pathological states in the rat and mouse. Bile duct proliferation induced by the administration of alpha-naphthylisothiocyanate (ANIT) as well as the oval cell proliferation induced by 3''-methyl-4-dimethylaminoazobenzene (3-MeDAB) have been used to examine the expression of the rodent cytokeratins in the proliferating cells regarded as being of bile duct origin. Examples of cholangiofibrosis and cholangiocarcinomas were also examined for evidence of cytokeratin expression using this antibody, as well as proliferations of a morphological intermediate type between epithelial and mesenchymal. In all cases we have been able to demonstrate continuity of phenotypic expression of the cytokeratins recognized by this antibody in cells which are recognized as bile duct in origin, even where their morphological appearance does not resemble an epithelial cell type. Because this antibody can be used on formalin-fixed, paraffin-processed tissues, after trypsin treatment, it is proposed that it can be used routinely in the toxicological evaluation (even retrospectively) of bile duct related proliferations and tumours.