The diagnostic utility of the keratin profiles of hepatocellular carcinoma and cholangiocarcinoma

Histopathological Evaluation and Molecular Diagnostic Tests for Peritoneal Metastases with Unknown Primary Site-a Review

Cancer of unknown primary (CUP) is a well-studied entity with guidelines available for the management of patients with CUP. The peritoneum represents one of the metastatic sites in CUP, and peritoneal metastases (PM) could present as CUP. PM of unknown origin remains a poorly studied clinical entity. There is only one series of 15 cases, one population-based study, and few other case reports on this subject. Studies on CUP, in general, cover some common tumour histological types like adenocarcinomas and squamous carcinomas. Some of these tumours may have a good prognosis though majority have high-grade disease with a poor long-term outcome. Some of the histological tumour types commonly seen in the clinical scenario of PM like mucinous carcinoma have not been studied. In this review, we divide PM into five histological types-adenocarcinomas, serous carcinomas, mucinous carcinomas, sarcomas and other rare varieties. We provide algorithms to identify the primary tumour site using immunohistochemistry when imaging, and endoscopy fails to establish the primary tumour site. The role of molecular diagnostic tests for PM or unknown origin is also discussed. Current literature on site-specific systemic therapy based on gene expression profiling does not show a clear benefit of this approach over empirical systemic therapies.

Hepatocellular carcinomas in captive prosimians

We performed a retrospective examination of spontaneous hepatocellular carcinomas (HCCs) (primary and metastatic tumors) in 14 captive prosimians brought to the Veterinary Medical Diagnostic Laboratory in North Carolina State University over a period of 11 years (2003 to 2014) to characterize the tumors. These animals are endangered primates; a better understanding of the main fatal neoplasms is crucial. In addition to the histologic evaluation, an immunohistochemical study was also performed, using a hepatocyte marker (hepatocyte paraffin 1 [HepPar-1]) and 2 cholangiocyte markers (keratin 7 [K7] and keratin 19 [K19]), in an attempt to identify a specific profile for HCCs with metastatic behavior. Six of the 14 HCCs had pulmonary metastases. The most frequent histopathological findings were a trabecular pattern (14/14, 100%), presence of multinucleated cells (12/14, 85.7%), and foci of extramedullary hematopoiesis (9/14, 64.3%). The mitotic count was significantly higher in the metastatic HCCs (P < .05). HepPar-1 was detected in all primary and metastatic HCCs, with a strong intensity of staining. Labeling for K7 and K19 was positive in 12 HCCs (85.7%) and 1 HCC (7.1%), respectively. Contrary to the less aggressive HCCs, most of the metastatic HCCs (5/6) expressed K7 in more than 15% of cells. The percentage of K7-positive neoplastic hepatocytes was significantly higher in metastatic HCCs. This study suggests that K7 might be a prognostically relevant marker in HCCs of captive prosimians.

Oncogenic KRAS Requires Complete Loss of BAP1 Function for Development of Murine Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a primary biliary malignancy that harbors a dismal prognosis. Oncogenic mutations of KRAS and loss-of-function mutations of BRCA1-associated protein 1 (BAP1) have been identified as recurrent somatic alterations in ICC. However, an autochthonous genetically engineered mouse model of ICC that genocopies the co-occurrence of these mutations has never been developed. By crossing Albumin-Cre mice bearing conditional alleles of mutant Kras and/or floxed Bap1, Cre-mediated recombination within the liver was induced. Mice with hepatic expression of mutant Kras^G12D alone (KA), bi-allelic loss of hepatic Bap1 (B^homoA), and heterozygous loss of Bap1 in conjunction with mutant Kras^G12D expression (B^hetKA) developed primary hepatocellular carcinoma (HCC), but no discernible ICC. In contrast, mice with homozygous loss of Bap1 in conjunction with mutant Kras^G12D expression (B^homoKA) developed discrete foci of HCC and ICC. Further, the median survival of B^homoKA mice was significantly shorter at 24 weeks when compared to the median survival of ≥40 weeks in B^hetKA mice and approximately 50 weeks in B^homoA and KA mice (p < 0.001). Microarray analysis performed on liver tissue from KA and B^homoKA mice identified differentially expressed genes in the setting of BAP1 loss and suggests that deregulation of ferroptosis might be one mechanism by which loss of BAP1 cooperates with oncogenic Ras in hepato-biliary carcinogenesis. Our autochthonous model provides an in vivo platform to further study this lethal class of neoplasm.

Immunohistochemical Signature Add Prognostic Value in Patients With Early and Intermediate Hepatocellular Carcinoma Underwent Curative Liver Resection

Hepatocellular carcinoma (HCC) is the third most lethal cancer worldwide; however, accurate prognostic tools are still lacking. We aimed to identify immunohistochemistry (IHC)-based signature as a prognostic classifier to predict recurrence and survival in patients with HCC at Barcelona Clinic Liver Cancer (BCLC) early- and immediate-stage. In total, 567 patients who underwent curative liver resection at two independent centers were enrolled. The least absolute shrinkage and selection operator regression model was used to identify significant IHC features, and penalized Cox regression was used to further narrow down the features in the training cohort (n = 201). The candidate IHC features were validated in internal (n = 101) and external validation cohorts (n = 265). Three IHC features, hepatocyte paraffin antigen 1, CD34, and Ki-67, were identified as candidate predictors for recurrence-free survival (RFS), and were used to categorize patients into low- and high-risk recurrence groups in the training cohort (P < 0.001). The discriminative performance of the 3-IHC_based classifier was validated using internal and external cohorts (P < 0.001). Furthermore, we developed a 3-IHC_based nomogram integrating the BCLC stage, microvascular invasion, and 3-IHC_based classifier to predict 2- and 5-year RFS in the training cohort; this nomogram exhibited acceptable area under the curve values for the training, internal validation, and external validation cohorts (2-year: 0.817, 0.787, and 0.810; 5-year: 0.726, 0.662, and 0.715; respectively). The newly developed 3-IHC_based classifier can effectively predict recurrence and survival in patients with early- and intermediate-stage HCC after curative liver resection.

Comparative Analysis of Immunohistochemical Markers for Differential Diagnosis of Hepatocelluar Carcinoma and Cholangiocarcinoma

Aims and background

Differential diagnosis of hepatocellular carcinoma and intrahepatic cholangiocarcinoma is sometimes difficult to accurately perform.

Methods

Eight markers including cytokeratin 7 (CK7), cytokeratin 19 (CK19), MOC31, CD10, glypican 3 (GPC3), claudin 4, biglycan and high mobility group A1 (HMGA1) were immunohistochemically stained in samples from 179 surgically resected hepatocellular carcinomas and 127 intrahepatic cholangiocarcinomas, and the rates of marker expression were statistically compared.

Results

With the exception of biglycan, 7 of the 8 markers were found to have significantly different expression patterns when comparing the two types of cancer (P <0.05). In intrahepatic cholangiocarcinomas, the expression rates of CK7, CK19, MOC31, claudin 4 and HMGA1 were 83.4%, 89.0%, 88.2%, 69.2%, and 31.5%, respectively. These rates of expression in intrahepatic cholangiocarcinomas were all higher than in those in hepatocellular carcinomas (CK7, 31.3%; CK19, 10.1%; MOC31, 34.0%; claudin 4, 11.2%; and HMGA1, 19.5%). The expression rates of GPC3, CD10, and biglycan were 72.6%, 39.7% and 10.0%, respectively, in hepatocellular carcinoma. These were higher than the rates found in intrahepatic cholangiocarcinomas (GPC3, 7.0%; CD10, 18.1%; and biglycan, 7.0%). In a multivariate logistic regression analysis, GPC3, CK19, MOC31 and claudin 4 were found to be independent markers for differentially diagnosing intrahepatic cholangiocarcinoma.

Conclusions

Based on our results, GPC3 and CK19 can be used as first-line markers for differential diagnoses of hepatocellular carcinoma and intrahepatic cholangiocarcinoma (accuracy rate, 73.5%), and additional combined screening for claudin 4 and MOC31 markers in GPC3(-) and CK19(-) tumors might increase the accuracy rate for distinguishing hepatocellular carcinoma from intrahepatic cholangiocarcinoma to 88.5%.

Pathology of Liver Metastases

BACKGROUND

The liver is the most frequent site of metastatic disease, and metastatic disease to the liver is far more common than primary liver carcinoma in the United States. Pathologic evaluation of biopsy samples is key to establishing a correct diagnosis for patient management. Morphologic and immunoperoxidase studies, which are the standard for pathologic practice, accurately classify most tumors. Subclassification of carcinoma of unknown primary remains problematic.

METHODS

The author reviewed the literature for articles pertaining to liver biopsy, diagnosis of specific tumor types, utility of immunohistochemical markers, and microarray and proteomic analysis.

RESULTS

Sampling of liver lesions is best accomplished by combining fine-needle aspiration and needle core biopsy. Many malignancies have distinct morphologic and immunohistochemical patterns and can be correctly subclassified. Adenocarcinoma of unknown primary remains enigmatic since current immunohistochemical markers for this differential diagnosis lack specificity. Microarray analysis and proteomic analysis of tumors can provide distinct gene or protein expression profiles, respectively, for tumor classification. These technologies can be used with fine-needle aspiration and needle core biopsy samples.

CONCLUSIONS

Most metastatic malignancies in the liver may be correctly diagnosed using standard morphology and immunohistochemical techniques. However, subtyping of some carcinomas and identification of site of unknown primary remains problematic. New technologies may help to further refine our diagnostic capabilities.

Characterization of inflammatory (lymphoepithelioma-like) hepatocellular carcinoma: a study of 8 cases

CONTEXT

The World Health Organization has recently recognized lymphoepithelioma-like carcinoma, or inflammatory hepatocellular carcinoma, as a variant of hepatocellular carcinoma.

OBJECTIVE

To identify and characterize the inflammatory hepatocellular carcinomas in our institution from 1988 to the present.

DESIGN

All cases of hepatocellular carcinoma in our institution from 1988 to the present were reviewed and reclassified as lymphoepithelioma-like carcinoma and were studied in comparison to appropriately matched controls.

RESULTS

Among the 8 cases of lymphoepithelioma-like carcinoma identified, the male to female ratio was 1:3, the mean age was 68.5 years (range, 57-78 years), and all of the cases were seen in noncirrhotic livers. The average numbers of lymphocytes were significantly higher in the cases than in the controls. T cells were predominant, with a uniform distribution of CD4 and CD8 positive cells. Cholangiolar differentiation was seen by K19 positivity as focal in 1 case and diffuse in 2 cases. In situ hybridization for Epstein-Barr virus was negative in all of the cases. Diffuse overexpression of p16 (>75% of cells) was seen in 2 cases, both of which were negative for the presence of transcriptionally active human papilloma virus by in situ hybridization. In our series, 3 of 8 cases (37.5%) showed local recurrence, which was similar to the controls (6 of 18; 33%), P > .99. Although the rate of distant metastases was lower among the cases (12.5%) than the controls (22.2%), the difference was not statistically significant (P > .99).

CONCLUSION

We present the first series of 8 cases of lymphoepithelioma-like carcinoma of the liver occurring in patients without cirrhosis and with a female preponderance and the absence of Epstein-Barr virus. Although clinical outcomes were similar to those of controls in our small series, additional data may be required for confirmation.

Immunohistochemical features of the gastrointestinal tract tumors

Gastrointestinal tract tumors include a wide variety of vastly different tumors and on a whole are one of the most common malignancies in western countries. These tumors often present at late stages as distant metastases which are then biopsied and may be difficult to differentiate without the aid of immunohistochemical stains. With the exception of pancreatic and biliary tumors where there are no distinct immunohistochemical patterns, most gastrointestinal tumors can be differentiated by their unique immunohistochemical profile. As the size of biopsies decrease, the role of immunohistochemical stains will become even more important in determining the origin and differentiation of gastrointestinal tract tumors.

Expression of K19 and K7 in dysplastic nodules and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common types of malignant tumors characterized by a multistep process of tumor development. Nodular lesions that differ from the surrounding liver parenchyma and are characterized by cytological or structural atypia are termed dysplastic nodules (DNs). DNs are well-known precancerous HCC lesions. Expression of keratin (K) 19 and K7, molecular markers of hepatic progenitor cells and cholangiocytes, has been reported in certain HCCs. However, it remains unclear whether K19-positive HCC cells are derived from true hepatic progenitor cells or mature cells that have undergone a dedifferentiation or a transdifferentiation process. In total, 107 tissue sections (13 low-grade DNs, 15 high-grade DNs, 27 small HCCs and 52 large HCCs) from resected liver samples and 132 HCC tissue microarray (TMA) cores were subjected to immunohistochemical analysis for K19 and K7. Clinicopathological data of the HCC patients were evaluated. K19 expression was found in 0% of DNs, 19% of small HCCs (≤2 cm), 8% of large HCCs (>2 cm) and 8% of TMA samples. K7 expression was found in 14% of DNs, 41% of small HCCs, 15% of large HCCs and 6% of TMA samples. Among the five K19-positive small HCCs, four were distinctly nodular and one tumor was an infiltrative type. No vaguely nodular HCC was positive for K19. K19 expression was significantly associated with histological grade (P=0.023), serum α-fetoprotein level (P=0.001) and K7 expression (P=0.001) in HCC. K19 expression was an independent prognostic factor for overall survival in non-viral HCC patients (P=0.003). K19 expression is extremely rare in DNs and occurs in progressed small HCCs. Our results suggest that K19 expression may be an acquired feature of carcinoma cells during HCC progression in certain HCCs.

Wisteria floribunda agglutinin-positive mucin 1 is a sensitive biliary marker for human cholangiocarcinoma

Cholangiocarcinoma (CC) is an aggressive malignant tumor for which useful markers are not presently available for early and precise diagnosis. The aim of this study was therefore to identify a high-performance diagnostic marker with a special focus on glyco-alteration of glycoproteins. In the course of study, we found that Wisteria floribunda agglutinin (WFA) is the best probe to differentiate intrahepatic cholangiocarcinoma (ICC) lesions from normal bile duct epithelia (BDE) (P < 0.0001). The subsequent histochemical study confirmed ICC-specific WFA staining on 165 tissue specimens. On the other hand, the WFA staining was shown to be closely associated with that of MY.1E12 established previously against sialylated mucin 1 (MUC1) by double-staining experiments. Moreover, glyco-alteration of MUC1 could be verified by western blotting of WFA-captured bile samples from patients with CC patients. Thus, we attempted to construct an enzyme-linked immunosorbent assay system for more convenient CC diagnosis, where WFA-coated plates, the specific monoclonal antibody MY.1E12, and the bile specimens from CC including ICC (n = 30) and benign diseases (n = 38) were combined. As a result, CC was clearly distinguished from benign diseases with statistical scores (sensitivity = 90.0%, specificity = 76.3%, and area under the curve = 0.85). As a particular note, the obtained sensitivity is the highest score among those having been so far reported.

CONCLUSION

Our approach focusing significant glyco-alteration of a particular glycoprotein yielded a novel diagnostic system for CC with satisfactory clinical scores.

p38delta/MAPK13 as a diagnostic marker for cholangiocarcinoma and its involvement in cell motility and invasion

Cholangiocarcinoma (CC) and hepatocellularcarcinoma (HCC) are two main forms of liver malignancies, which exhibit differences in drug response and prognosis. Immunohistotochemical staining for cytokeratin markers has been used to some success in the differential diagnosis of CC from HCC. However, there remains a need for additional markers for increased sensitivity and specificity of diagnosis. In this study, we have identified a p38 MAP kinase, p38delta (also known as MAPK13 or SAPK4) as a protein that is upregulated in CC relative to HCC and to normal biliary tract tissues. We performed microarray gene expression profiling on 17 cases of CC, 12 cases of adjacent normal liver tissue, and three case of normal bile duct tissue. p38delta was upregulated in 16 out of 17 cases of CC relative to normal tissue. We subsequently performed immunohistochemical staining of p38delta in 54 cases of CC and 54 cases of HCC. p38delta staining distinguished CC from HCC with a sensitivity of 92.6% and a specificity of 90.7%. To explore the possible functional significance of p38delta expression in CC, we examined the effects of overexpression and knockdown of p38delta expression in human CC cell lines. Our results indicate that p38delta is important for motility and invasion of CC cells, suggesting that p38delta may play an important role in CC metastasis. In summary, p38delta may serve as a novel diagnostic marker for CC and may also serve as a new target for molecular based therapy of this disease.

Cytokeratin 8/18 as a new marker of mouse liver preneoplastic lesions

To search for a reliable biomarker of preneoplastic lesions arising early in mouse hepatocarcinogenesis the proteomes of microdissected basophilic foci, hepatocellular adenomas (HCAs), carcinomas (HCCs) and normal-appearing liver of B6C3F1 mice initiated with diethylnitrosamine (DEN) were analysed on anionic (Q10) surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) ProteinChip arrays. Significant overexpression of cytokeratin 8 (CK8; m/z 54, 565), cytokeratin 18 (CK18; m/z 47,538) proteins was found in basophilic foci as well as in HCAs and HCCs. Furthermore, immunohistochemistry demonstrated profound overexpression of CK8 and CK18 proteins (CK8/18) in all basophilic foci, mixed cell type foci, HCAs and HCCs in B6C3F1 and C57BL/6J mice initiated with DEN. A strong correlation between CK8/18-positive foci development and multiplicity of liver tumors in B6C3F1 and C57Bl/6J mice was further observed. Moreover, formation of CK8 and CK18 complexes due to CK8 phosphorylation at Ser73 and Ser431 was found to be strongly associated with neoplastic transformation of mice liver basophilic foci. Elevation of CK8/18 was strongly correlated with induction of cell proliferation in basophilic foci and tumors. In conclusion, our data imply that CK8/18 is a novel reliable marker of preneoplastic lesions arising during mouse hepatocarcinogenesis which might be used for prediction of tumor development and evaluation of environmental agents as well as drugs and food additives using mouse liver tests.

Cytokeratin 8/18 overexpression and complex formation as an indicator of GST-P positive foci transformation into hepatocellular carcinomas

Screening of the proteome of microdissected glutathione S-transferase placental form (GST-P) positive foci and normal-appearing liver on anionic (Q10), and cationic (CM10) surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) ProteinChip arrays demonstrated significant overexpression of cytokeratin 8 (CK8; m/z 54,020), cytokeratin 18 (CK18; m/z 47,760), microsomal cytochrome 5A (m/z 15,224) and histone type 2 H2aa3 (m/z 15,964) in the livers of rats initiated with diethylnitrosamine (DEN) followed by 10 weeks on phenobarbital (PB) at a dose of 500 ppm. Furthermore, formation of CK8 and CK18 complexes due to CK8 phosphorylation at Ser73 and Ser431 was found to be strongly associated with promotion of hepatocarcinogenesis by PB and the development of hepatocellular carcinomas. The data were confirmed by immunohistochemistry and real-time Q-PCR and profound overexpression of CK8 and CK18 (CK8/18) proteins and mRNAs were detected in several large size GST-P positive foci and liver tumors. A strong correlation between CK8/18 positive foci development and multiplicity of hepatocellular carcinomas was further observed. Moreover, elevation of CK8/18 was strongly associated with induction of cell proliferation in GST-P positive foci and tumors. In conclusion, our data imply that CK8/18 overexpression, those two cytokeratins complex formation associated with histone type 2 H2aa3 up-regulation and intermediate filament reorganization may drive neoplastic transformation of GST-P positive foci during rat hepatocarcinogenesis leading to the formation of hepatocellular carcinomas.

Identification of novel candidate tumour marker genes for intrahepatic cholangiocarcinoma

BACKGROUND/AIMS

Specific markers are required for early detection and diagnosis of intrahepatic cholangiocarcinoma (ICC); however, the tumour markers currently in use are not specific for ICC.

METHODS

We compared an ICC cDNA library with that of hepatocellular carcinoma (HCC) by serial analysis of gene expression (SAGE). The expression patterns in each were confirmed by quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR), immunoblotting and immunohistochemical analysis of 74 samples including 16 ICC samples.

RESULTS

A comparison of the two libraries revealed distinct gene expression patterns for each type of liver cancer. In addition to the known tumour markers, we detected nine novel genes associated with ICC. By comparing the mean transcript abundance in the ICC library with those in other libraries, including gastric, colon, prostate and breast cancer, together with our RT-PCR results, we identified three genes as specific markers of ICC: biglycan, insulin-like growth factor-binding protein 5 and claudin-4. Immunoblotting and immunohistochemical analyses showed that claudin-4 was highly expressed in ICC. Moreover, discrimination analysis revealed that a combination of these genes could be used to distinguish ICC from HCC or metastatic adenocarcinoma.

CONCLUSIONS

We identified novel marker genes of ICC that are potentially useful for the diagnosis of liver cancer.

A case of combined hepatocellular-cholangiocarcinoma with underlying schistosomiasis

Combined hepatocellular-cholangiocarcinoma is a rare form of primary liver cancer showing features of both hepatocellular and biliary epithelial differentiation. We report here on a case with collision tumor, which apparently was the coincidental occurrence of both hepatocellular carcinoma and cholangiocarcinoma underlying schistosomiasis. A 39-year-old-Philippine female was transferred to our hospital for evaluation of a liver mass that was found on ultrasonography at a local hospital. HBsAg and Anti-HCV were negative and serum alpha-fetoprotein (AFP) level was normal. The tumor mass was histologically diagnosed as adenocarcinoma by sono-guided biopsy before the operation. Partial lobectomy was performed and we histologically identified the concurrent occurrence of hepatocellular carcinoma and cholangiocarcinoma, (a "collision type carcinoma").

Clinicopathological implications of immunohistochemically demonstrated mucin core protein expression in hepatocellular carcinoma

METHODS

We examined the expression of mucin core protein 1 (MUC1) immunohistochemically in 186 surgical specimens of histopathologically nonmucinous hepatocellular carcinoma (HCC) and compared the clinicopathological features in patients with MUC1-positive HCC (MUC1-positive group) with those in patients with MUC1-negative HCC (MUC1-negative group).

RESULTS

MUC1 immunoreactively was present in 85 of the 186 HCCs. Of the clinicopathological variables examined, the serum concentration of alpha-fetoprotein, tumor differentiation, bile duct invasion, lymph node metastasis, and cytokeratin 19 expression exhibited significant associations with MUC1 expression. Although cumulative and tumor-free survival rates were not different between the two groups, the percentage of patients with first recurrence of HCC in distant organs (distant metastasis) within 2 years after surgery was significantly higher in the MUC1-positive group than in the MUC1-negative group (P = 0.0104). The risk ratio of MUC1 positivity for this type of distant metastasis was 3.156 (95% confidence interval, 1.064-9.358).

CONCLUSIONS

In patients with MUC1-positive HCC, careful follow-up is necessary, not only for intrahepatic recurrence but also for distant metastasis, after the resection of primary HCC.

Clinical significance of serum cytokeratin-19 fragment (CYFRA 21-1) in hepatocellular carcinoma

BACKGROUND/PURPOSE

CYFRA 21-1, a soluble fragment of cytokeratin 19, is increased in serum in some patients with hepatocellular carcinoma, but the clinical significance of this increase is still unknown.

METHODS

Serum concentrations of CYFRA 21-1 were measured in 240 patients with hepatocellular carcinoma prior to hepatic resection. The relationships between serum CYFRA 21-1 concentrations and clinicopathologic features were analyzed.

RESULTS

The sensitivity of CYFRA 21-1 as a test for hepatocellular carcinoma was 18.8%. Serum CYFRA 21-1 was significantly higher in patients with portal vein tumor thrombus, and serum CYFRA 21-1 increased with the progression of portal vein tumor thrombus. Tumor size was related to serum CYFRA 21-1, but there were no significant correlations between serum CYFRA 21-1 concentrations and tumor differentiation or number of tumors. Although patients with stage IV tumor had significantly higher CYFRA 21-1 concentrations than those with stages I, II, and III, CYFRA 21-1 was not associated with postoperative prognosis.

CONCLUSIONS

Although high concentrations of CYFRA 21-1 were often detected in patients with a tumor diameter greater than 5 cm or tumor thrombus in the major portal vein, CYFRA 21-1 is not a useful diagnostic tool for hepatocellular carcinoma because of its low sensitivity.

Hepatocellular carcinoma with mesothelioma-like dissemination

Reported herein is a case of hepatocellular carcinoma (HCC) with unusual peritoneal dissemination masquerading as peritoneal mesothelioma. A 61-year-old man was clinically found to have multiple tumors in his abdominal cavity; peritonitis carcinomatosa was suspected. An autopsy revealed numerous tumors of various sizes in the abdominal serosa, omentum, and diaphragm. No signs of tumor, fibrosis, or cirrhosis were found in the liver, except for a small nodule in the hepatic triangular ligament. Histologically, the tumor cells proliferated in thick trabeculae or in sheets and formed a few canaliculi and tubules with homogenously brown contents in their lumina, which stained positively with Hall stain. Immunohistochemically, these tumors were positive for hepatocyte, alpha-fetoprotein (AFP) and low-molecular-weight cytokeratin; were focally positive for pan-cytokeratin and epithelial membrane antigen (EMA); and were negative for high-molecular-weight cytokeratin, vimentin, and calretinin. Carcinoembryonic antigen (CEA) produced a bile canalicular immunohistochemical staining pattern. Thus, the tumor was diagnosed as an HCC (Edmondson II type) of the triangular ligament with massive peritoneal dissemination. The origin of this tumor and its differential diagnosis (malignant mesothelioma, hepatoid adenocarcinoma, and hepatoid yolk sac tumor) are discussed.

Upregulation of Glypican-3 expression in hepatocellular carcinoma but downregulation in cholangiocarcinoma indicates its differential diagnosis value in primary liver cancers

BACKGROUND/AIM

Expression alteration of Glypican-3 (GPC3) is associated with several malignancies and has been identified as an overexpressed gene in hepatocellular carcinoma (HCC). In this study GPC3 expression in intrahepatic chanlangiocarcinoma (ICC), gallbladder cancer and HCC was quantitatively detected.

METHODS

Real-time quantitative reverse transcription polymerase chain reaction was used to detect the expression level of GPC3.

RESULTS

GPC3 expression was elevated more than two-fold in HCC compared with adjacent tissue in 90 of 100 HCC cases. The average expression level of GPC3 was significantly higher in HCC than that in adjacent liver tissues (P<0.0001). Only in four of 21 ICC cases GPC3 expression was upregulated more than two-fold in tumor tissues. GPC3 expression was downregulated in gallbladder cancer in 12 of 13 cases and the average expression level was significantly lower than that in normal gallbladder tissues (P<0.05).

CONCLUSION

The different expression patterns of GPC3 in HCC and ICC suggested that it might play a different role in theses tumors and could serve as a biomarker for differential diagnosis of HCC and ICC.

Recent immunohistochemical markers in the differential diagnosis of primary and metastatic carcinomas of the liver

Differential diagnosis of primary and metastatic carcinomas of the liver can be problematic and may require immunohistochemical work-up. Recently, new immunohistochemical markers have been introduced with promising results in this area. We studied three of these markers, human hepatocyte antibody (HepPar-1), human epithelial-related antigen (MOC-31), and thyroid transcription factor-1 (TTF-1), in cell-block sections of fine-needle aspirations from 30 hepatocellular carcinomas and 27 metastatic carcinomas from various sites. Of 27 metastatic carcinomas, all but one were positive for MOC-31 and, all but one were negative for HepPar-1. TTF-1 was positive only in the nuclei of metastatic poorly differentiated neuroendocrine carcinoma from the lung. Of 30 hepatocellular carcinomas, 26 were positive for HepPar-1 and all were negative for MOC-31, while TTF-1 showed cytoplasmic staining in 23 cases. HepPar-1, MOC-31, and TTF-1 are complementary markers in the differential diagnosis of primary and metastatic carcinomas of the liver, with high sensitivity and specificity.

A case report of hepatocellular carcinoma and focal nodular hyperplasia with a myelolipoma in two chimpanzees and a review of spontaneous hepatobiliary tumors in non-human primates

Spontaneous hepatobiliary tumors in non-human primates are uncommon. Here we report a case of hepatic carcinoma and a case of hepatic focal nodular hyperplasia (FNH) and myelolipoma in two captive chimpanzees. A 16-year-old male chimpanzee (4X0392) died after an 8-month history of hepatic amyloidosis and low-grade anemia. Necropsy findings included a hepatic neoplasm with highly pleomorphic hepatocytes arranged into irregular thickened trabeculae. The diagnosis was high-grade hepatocellular carcinoma. A second male chimpanzee (4X0080), 23 years of age, died suddenly of heart failure secondary to cardiomyopathy. An incidental finding at necropsy was a liver mass characterized by multinodularity, prominent fibrous septa, and biliary hyperplasia. These features were consistent with FNH. While 4X0392 had no history of experimental viral exposure, 4X0080 was vaccinated with inactivated hepatitis B virus, an attenuated hepatitis A virus, and was experimentally infected with hepatitis C virus and human immunodeficiency virus. A survey of the literature revealed 68 reported cases of hepatobiliary tumors in non-human primates, including 12 hepatocellular adenomas, eight cholangiocellular adenomas/cystadenomas, 22 hepatocellular carcinomas, seven cholangiocarcinomas, and seven gallbladder adenocarcinomas. The majority of reported cases have been in prosimians and Old World monkeys. Hepatic neoplasia is rare in chimpanzees. Only four hepatic neoplasms have been reported in chimpanzees, three of which were associated with viral hepatitis. FNH has not been previously described in any non-human primate.

Cytokeratin 19 expression in hepatocellular carcinoma predicts early postoperative recurrence

Clinicopathologic features and postoperative outcomes were investigated for patients who underwent curative surgery for biliary marker (CK7 and CK19)-positive hepatocellular carcinoma (HCC). Of 157 HCCs, 93 were CK7(-)CK19(-), 49 were CK7(+)-CK19(-), 1 was CK7(-)CK19(+), and 14 were CK7(+)- CK19(+). Semiquantitative analysis of expression levels demonstrated a significant correlation between CK7 and CK19 expression. Of various clinicopathologic parameters, tumor differentiation exhibited a significant correlation with CK7 and CK19 expression. All 15 patients with CK19-positive HCC also had anti-HBc. Log-rank test revealed that CK7 expression, CK19 expression, high aspartate aminotransferase (AST) activity, low albumin concentration, portal invasion, intrahepatic metastasis, and severe fibrosis (cirrhosis) reduced the tumor-free survival rate. Multivariate analysis demonstrated that CK19 expression, intrahepatic metastasis, and severe fibrosis were independent predictors of postoperative recurrence, while CK7 expression was not. Twelve of 15 patients with CK19-positive HCC had tumor recurrence within 2 years after surgery, a significantly higher incidence of early recurrence than for CK19-negative HCC. The incidence of extrahepatic disease, especially lymph node metastasis, was significantly higher for patients with CK19-positive HCC. These findings indicate that CK19 expression is a predictor of early postoperative recurrence due to increased invasiveness.

Hepatoid carcinoma of the ovary: a report of three cases admixed with a common surface epithelial carcinoma

Hepatoid carcinoma of the ovary is an ovarian carcinoma that has phenotypic properties in common with hepatocellular carcinomas. However, the extent of the tumor cells' similarity to and their difference from hepatocytes is largely unknown. In addition, the precursor cell of origin for hepatoid carcinoma of the ovary has not been identified. Three cases of alpha-fetoprotein-producing hepatoid carcinoma of the ovary that were admixed with an adenocarcinoma of common surface epithelial type are reported. The hepatoid carcinomas had a trabecular architecture with canaliculi detected by polyclonal (but not monoclonal) anticarcinoembryonic antigen antibodies. A hepatic phenotype in the hepatoid tumor cells was further supported by the production of albumin mRNA by in situ hybridization. The adenocarcinomas in the three cases were mucinous (Case 1), serous (Case 2), and endometrioid (Case 3), respectively. The cytokeratin (CK) profile in both the hepatoid and adenocarcinomatous components was CK18+/CK19+/CK20+/-, whereas normal and neoplastic hepatocytes were CK18+/CK19-/CK20-. Although this study supports a hepatic phenotype in ovarian hepatoid carcinoma, the CK profile of hepatoid carcinoma differs from that of normal and neoplastic hepatocytes but resembles that of the associated common epithelial adenocarcinoma. These findings suggest that hepatoid carcinoma of the ovary is probably derived from carcinomas of surface epithelial origin by a process of neometaplasia or transdifferentiation.

Cytokeratin-19 fragments in serum (CYFRA 21-1) as a marker in primary liver cancer

Using an electrochemiluminescence immunoassay, CYFRA 21-1 concentrations were measured in sera from 187 patients with primary liver cancer (164 with hepatocellular carcinoma (HCC) and 23 with intrahepatic cholangiocarcinoma (ICC)) and 87 patients with benign liver diseases. Concentrations of CYFRA 21-1 were significantly higher in patients with ICC (5.0; interquartile range 3.1-10.7 ng ml(-1)) than in those with benign liver disease (1.4; 1.0-1.9; Mann-Whitney U-test, P<0.0001) or HCC (1.7; 1.1-2.7; Mann-Whitney U-test, P<0.0001). Using cutoff values selected for 95% specificity in the benign group (3.0 ng ml(-1)), CYFRA 21-1 showed higher sensitivity for ICC (87.0%) than three commonly used markers including alpha-fetoprotein (17.4%), carcinoembryonic antigen (34.8%), and carbohydrate antigen 19-9 (60.9%). Serum CYFRA 21-1 increased in ICC from stages I/II to IV (Kruskal-Wallis test, P=0.0102). CYFRA 21-1 concentration increased with extent of local invasion, but not nodal status. Serum CYFRA 21-1 represents a useful diagnostic test for ICC that offers high sensitivity. CYFRA 21-1 reflected differences in tumour burden, suggesting applicability to staging and follow-up.

Comparative immunohistochemical profile of hepatocellular carcinoma, cholangiocarcinoma, and metastatic adenocarcinoma

Distinguishing hepatocellular carcinoma (HCC) from cholangiocarcinoma (CC) and metastatic adenocarcinoma (MA) involving the liver can be problematic, often requiring the use of immunohistochemistry to facilitate diagnosis. Hep Par 1, a monoclonal antibody with expression confined primarily to benign and malignant hepatocytes, has recently become commercially available. We evaluated Hep Par 1 along with other immunohistochemical markers used to differentiate HCC, CC, and MA, including AE1/AE3, CAM 5.2, B72.3, monoclonal carcinoembryonic antigen (mCEA), polyclonal CEA (pCEA), alpha-fetoprotein (AFP), factor XIIIa, inhibin, CD10, villin, MOC-31, cytokeratin (CK) 7, CK 19, and CK 20, to determine the markers most useful in differentiating these entities. Forty-two cases of HCC, 9 cases of CC, and 56 cases of MA (24 colon, 15 pancreas, 8 ovary, 5 breast, and 4 stomach) were studied. Hep Par 1 was sensitive and specific for HCC, with 38 of 42 (90%) cases staining positively, whereas reactivity was observed in only 8 of 56 (14%) MAs and 0 of 9 CCs. Though limited somewhat by poor sensitivity, a bile canalicular pattern of staining with pCEA, CD10, and villin was specific for HCC and was not observed in the other tumors. Lack of mCEA and MOC-31 immunoreactivity was also characteristic of HCCs. CK 19 positivity favored CC over HCC, but was not useful in differentiating CC from MA. Expression of AFP, although observed in only about one third of the cases, favored HCC over CC and MA. CK 7 and CK 20 were also useful in this differential diagnosis, particularly when dealing with MA of colonic origin. AE1/AE3, CAM 5.2, B72.3, inhibin, and factor XIIIa were noncontributory in differentiating these entities.

A case of primary myxoid leiomyosarcoma of the liver

Primary hepatic leiomyosarcoma is very rare and no primary myxoid leiomyosarcoma in the liver has been reported yet. Most cystic space-occupying lesions in the liver are benign in nature. But, rarely, malignancy could appear as a cystic lesion by ultrasonographic examination. A 64-year-old woman with a huge cystic mass detected by hepatic ultrasonography was diagnosed as primary hepatic myxoid leiomyosarcoma by immunohistochemical and ultrastructural studies after various image studies and fine needle aspiration biopsy of the liver mass.

Comparison of thyroid transcription factor-1 and hepatocyte antigen immunohistochemical analysis in the differential diagnosis of hepatocellular carcinoma, metastatic adenocarcinoma, renal cell carcinoma, and adrenal cortical carcinoma

We compared the effectiveness of thyroid transcription factor-1 (TTF-1, cytoplasmic reactivity) and hepatocyte antigen (HPA) as markers for characterization of hepatocellular carcinoma (HCC) and as discriminators to distinguish HCC from its histologic and cytologic mimics. Formalin-fixed, paraffin-embedded sections of 258 specimens, including 76 HCCs, 85 metastatic adenocarcinomas, 75 renal cell carcinomas (RCCs), and 22 adrenal cortical carcinomas (ACCs), were evaluated. Specimens included tissue sections and cytologic material (cell blocks). Following heat-induced epitope retrieval, immunohistochemical studies were performed using an indirect immunoperoxidase technique. Cytoplasmic reactivity for TTF-1 was noted for 54 (71%) of 76 HCCs, 3 (4%) of 85 adenocarcinomas, none of 72 RCCs, and none of 22 ACCs. Cytoplasmic reactivity for HPA was observedfor 50 (66%) of 76 HCCs, 1 (1%) of 83 adenocarcinomas, none of 74 RCCs, and none of 21 ACCs. Cytoplasmic reactivity for TTF-1 and HPA is highly specific for HCC, although a minority of HCCs, particularly poorly differentiated tumors, may be nonreactive. Thus, these markers are usefulfor the characterization of HCC in tissue sections and cell blocks and are highly effective for distinguishing these tumors from other neoplasms included in the differential diagnosis.

Diagnosis of hepatocellular carcinoma: fine needle aspiration cytology or needle core biopsy

Needle core biopsy (NCB) has been the standard procedure for histopathologic diagnosis of hepatic lesions for more than 50 years. In recent years fine needle aspiration cytology (FNAC) has emerged as a minimally invasive, relatively inexpensive and a rapid method of pathologic evaluation of primary or metastatic hepatic masses. The specificity and the positive predictive value of FNAC is very high however, the sensitivity of the procedure widely ranges between 67% to 93%. The two major areas of diagnostic difficulties are differentiation of benign and non-neoplastic hepatic nodules from well differentiated HCC and identification of obviously malignant cells as HCC, cholangiocarcinoma, or metastasis. Preparation of cell blocks, immunohistochemical stains and application of other ancillary techniques are often helpful in difficult cases. In presence of characteristic features a diagnosis of HCC can be established on FNAC however, a negative result does not exclude malignancy. The role of pathologic diagnosis in the assessment of large hepatic masses is well established however, its role in the evaluation of small hepatic nodules (<3 cm) detected during surveillance of high risk patients is still evolving. Considering the overall advantages and cost-analysis, FNAC can be suggested as the initial method of choice for evaluation of hepatic masses in most clinical settings. However, the final choice of the diagnostic procedure should be decided on the basis of working clinical diagnosis and the institutional experience.

Combined hepatocellular-cholangiocarcinoma: a histopathologic, immunohistochemical, and in situ hybridization study

Combined hepatocellular-cholangiocarcinoma (CHC) forms a small but significant proportion of primary liver carcinomas. However, its diagnostic features are not well established, and this has possibly contributed to the variability in its reported clinical outcome in the literature. Many such tumors with features intermediate between hepatocellular carcinoma and cholangiocarcinoma (CC) may have been considered CC in the past based on positivity for "biliary differentiation" cytokeratins and the lack of availability of highly sensitive and specific hepatocellular markers. The utility of in situ hybridization for albumin mRNA, a recently available sensitive and specific hepatocellular marker, has not been reported in CHC. We investigated 27 CHCs with regard to their histomorphologic spectrum and association of these morphologies with immunohistochemical staining for different cytokeratins (CK7, CK19, and CK20; AE1; Cam 5.2), epithelial membrane antigen, polyclonal carcinoembryonic antigen and alpha-fetoprotein, and in situ hybridization for albumin mRNA. All 27 tumors contained areas morphologically intermediate between hepatocellular carcinoma and CC (transitional-type tumors), and in each case such areas formed at least 25% of the tumor. Nine (33%) tumors showed areas with "antler-like" morphology, a feature not previously described in CHC. Twenty-two of 23 tumors (96%) showed positive signals on in situ hybridization for albumin mRNA. Positivity for both hepatocellular (albumin mRNA) and biliary (keratin immunohistochemical profile) markers confirmed the light microscopic impression of biphenotypic differentiation in these tumors. Immunohistochemical positivity for all cytokeratins (except CK7) and epithelial membrane antigen, as well as the expression of albumin mRNA by in situ hybridization, did not show significant differences between hepatocellular carcinoma and CC-like areas. Based on the cytokeratin profile and results on polyclonal carcinoembryonic antigen/alpha-fetoprotein alone, many such tumors would be classified as CC. However, the positivity for albumin mRNA by in situ hybridization proves that such an interpretation would not have been accurate. Clinically, CHCs showed many differences from pure hepatocellular carcinoma, including the absence of cirrhosis (0 of 27), rarity of serum hepatitis B or C marker positivity (4 of 27), and normal to only mildly elevated serum alpha-fetoprotein levels (median 187 ng/mL). The tumor followed an aggressive clinical course, with overall 3-and 5-year survival rates of 30% and 18%, and in the resected cases of 38% and 24%, respectively.

Keratin expression in human tissues and neoplasms

Keratin expression in human tissues and neoplasms Keratin filaments constitute type I and type II intermediate filaments (IFs), with at least 20 subtypes named keratin 1-20. Since certain keratin subtypes are only expressed in some normal human tissues but not others, and vice versa, various tissues have been subclassified according to the pattern of keratin staining. Simple epithelia generally express the simple epithelial keratins 7, 18, 19, and 20, while complex epithelia express complex epithelial keratins 5/6, 10, 14, and 15. When an epithelium undergoes malignant transformation, its keratin profile usually remains constant. The constitution and expression patterns of keratin filaments in human epithelial neoplasms are complex and often distinctive. In this article, we first briefly review the molecular and cell biology of keratin filaments. We then focus on the expression patterns of keratin filaments in various human neoplasms.

The role of immunohistochemistry in diagnosis

Immunohistochemistry is a strong tool in hepatopathologic diagnosis: the technique is relatively simple and inexpensive. New and very sensitive detection methods have been recently developed (e.g., the EnVision technique and the microwave antigen retrieval method). This article discusses the role of immunohistochemistry in differentiating chronic cholestatic diseases from chronic hepatitis and in characterizing infectious agents. Algorythms for the typing of lymphomas and for the differentiation of primary tumors versus metastases are proposed as well. The immunohistochemical criteria for the diagnosis of premalignant lesions are discussed.

Immature hepatic tumor of bimodal differentiation in a young adult patient: a novel lesion expressing beta-catenin and mimicking a distinct phase of hepatogenesis

PATIENT AND METHODS

A large right-sided liver tumor was incidentally discovered and totally resected in a 21-year-old female patient without chronic liver disease. Histopathologic examination revealed that this malignant tumor does not fit any of the known types of primary liver tumors reported thus far.

RESULTS

The lesion chiefly consisted of numerous solid nests composed of immature epithelial cells disclosing a marker profile typical for hepatocytes and strongly expressing beta-catenin. These nests were tightly associated with abnormal duct-like profiles exhibiting features of bile duct cells.

CONCLUSIONS

The finding of numerous neoplastic hepatobiliary units ('liverlets') suggests that this tumor may mimic a distinct developmental phase of hepatogenesis close to ductal plate formation.

Study of the malformation of ductal plate of the liver in Meckel syndrome and review of other syndromes presenting with this anomaly

Meckel syndrome (MIM 249.000) is an autosomal recessive disorder with a variable spectrum of anomalies. Since the first reports of this syndrome, very broad diagnostic criteria have been proposed, but the process of defining them continues. It is probable that at least two of three manifestations, including cystic kidney dysplasia, occipital encephalocele or other anomaly of the central nervous system, and postaxial polydactyly occur in most cases. Arrest of the development of intrahepatic bile ducts at the stage of the bilaminar plate formation or ductal plate malformation is considered of high diagnostic value in Meckel syndrome, but there is no complete agreement in the literature about its occurrence. The aims of this investigation were to study the prevalence and morphologic patterns of ductal plate malformation of the liver in Meckel syndrome by evaluating the dilatation of primitive biliary structures and the increase in connective tissue of the portal tract. Archival data files from four German centers (Berlin, Freiburg, Heidelberg, Mainz) were reviewed. Liver sections of 30 well-studied fetuses with Meckel syndrome were immunostained with antibodies against cytokeratins (intermediate filaments of the cytoskeleton) and factor VIII (an endothelial cell marker) and were evaluated both qualitatively and quantitatively. Cystic kidney dysplasia, occipital encephalocele, and postaxial polydactyly were found in 100%, 90%, and 83.3% of the fetuses, respectively. Ductal plate malformation of the liver was a constant anomaly in Meckel syndrome, seen as frequently as renal lesions. We observed essentially two kinds of hepatic lesions: 23 cases showed mainly a cystic dilatation of primitive biliary structures with little portal fibrosis, while 7 cases showed mainly rings of interrupted curved lumina around a central fibrovascular axis and pronounced portal fibrosis. In these seven cases an abnormal pattern of the portal vein, with many small and closely spaced branches of the portal vein (the so-called pollard willow pattern), was also seen. With respect to other fetal developmental anomalies, no difference between the two types of lesions was found. We also provide a potentially useful comprehensive review of other genetic syndromes in which ductal plate malformations may occur.

Immunohistochemical analysis of hepatocellular and adenocarcinoma in the liver: MOC31 compares favorably with other putative markers

Distinguishing hepatocellular carcinoma (HCC) from metastatic adenocarcinoma (MA) and cholangiocarcinoma (CC) can, at times, be difficult and sometimes requires immunohistochemical analysis. Recently, MOC31, an antibody directed against a cell surface glycoprotein, has been shown to be useful in separating HCC from both MA and CC; however, no study has compared MOC31 and other frequently used immunostains. We compare MOC31 with other commonly used immunostains for HCC, MA, and CC. Formalin-fixed, paraffin-embedded tissue sections from 57 previously characterized hepatic neoplasms (13 HCC, 14 CC, 3 combined HCC-CC, and 27 MA) were immunostained with antibodies directed against MOC31, cytokeratin (CK) 7, CK20, alpha-fetoprotein (AFP), polyclonal carcinoembryonic antigen, Ber-EP4, and Factor XIII-A. Two pathologists reviewed slides, and positivity was defined as more than 1% of cells staining with the appropriate pattern. Positive MOC31 immunostaining was seen in 0 of 13 HCC, 13 of 14 CC, 3 of 3 HCC-CC, and 27 of 27 MA; the staining was strong and diffuse. CK20 reactivity was observed in 0 of 13 HCC, 2 of 14 CC, 0 of 3 HCC-CC, and 12 of 27 MA; CK7 immunostained 4 of 13 HCC, 13 of 14 CC, 3 of 3 HCC-CC, and 15 of 27 MA; AFP was detected in 4 of 13 HCC and 2 of 3 HCC-CC, whereas all CC and MA were negative; polyclonal carcinoembryonic antigen showed immunoreactivity in 12 of 13 HCC and 3 of 3 HCC-CC in a canalicular pattern, whereas diffuse positivity was identified in 13 of 14 CC and 26 of 27 MA; Ber-EP4 immunostained 1 of 13 HCC, 14 of 14 CC, 2 of 3 HCC-CC, and 26 of 27 MA; and Factor XIII-A was negative in all HCC, CC, and MA. MOC31 expression distinguished HCC from adenocarcinoma in 56 of 57 cases. AFP was specific for HCC but was not sensitive. CK7 and CK20 have limited utility in distinguishing HCC from CC or MA, and Factor XIII-A is not useful. Ber-EP4 staining was similar to MOC31, but one HCC did stain with Ber-EP4. Polyclonal CEA yields similar numerical results as MOC31, but the focal nature of the staining and occasional difficulty in evaluating the pattern can make interpretation problematic. We conclude that MOC31 should be a component of the immunohistochemical panel to distinguish HCC from CC and MA.

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.

Structural and cell surface antigen expression in the rete ovarii and epoophoron differs from that in the Fallopian tube and in endometriosis

AIMS

We compared the immunohistochemical profiles of the rete ovarii and endometriosis in order to identify a panel which distinguishes between these structures. The immune profiles of the epoophoron, Fallopian tube and ovarian surface epithelium were also studied.

MATERIALS AND METHODS

Twenty-four women with no evidence of endometriosis and seven who had endometriosis in the uterine adnexae were studied using nine antibodies to intermediate filament proteins and cell surface markers. None of the structures studied shared an identical profile of immunohistochemical reaction. The immunoprofile of endometriosis showed some similarities to that of the Fallopian tube, but differed from that of the rete ovarii, epoophoron and ovarian surface epithelium

CONCLUSIONS

A panel including Ca-125, epithelial membrane antigen and the epithelial glycoprotein BerEp4 would permit the distinction between endometriosis and the rete ovarii in problematic cases. The study showed some commonality in reaction between endometriosis and the Fallopian tube which indicates that they may share a common (paramesonephric) origin. There was little commonality in the immunoprofile of endometriosis and the ovarian surface epithelium implying that endometriosis is unlikely to develop as a result of serosal metaplasia.

MOC31 immunoreactivity in primary and metastatic carcinoma of the liver. Report of findings and review of other utilized markers

Differentiating between primary tumors of the liver and metastatic lesions can, at times, be difficult. Various histochemical and immunohistochemical methods have been used in an effort to better delineate between hepatocellular carcinoma (HCC), especially the microglandular variant, primary cholangiocarcinoma, and metastatic adenocarcinoma; these ancillary studies can yield less than satisfactory results. Recently, anti-MOC31, a monoclonal antibody directed against a cell surface glycoprotein, has been shown to be helpful in distinguishing between adenocarcinoma and mesothelioma. This study addresses whether this antibody might be helpful in distinguishing between HCC, primary cholangiocarcinoma, and metastatic adenocarcinoma in the liver. Formalin-fixed, paraffin-embedded tissue sections from 15 HCC (including 10 microglandular variants), 14 primary cholangiocarcinomas, and 33 metastatic adenocarcinomas (7 colon, 1 lung, 8 breast, 4 GE jct/gastric, 9 pancreas, 2 small intestine, 1 renal, 1 ovary) were immunostained with anti-MOC 31 (1:40, Dako) after protease digestion and biotin block using a modified ABC technique. Positive staining was limited to membrane based reactivity; controls stained appropriately. Immunoreactivity for MOC31 was observed in 14 of 14 cholangiocarcinomas and 33 of 33 metastatic tumors. Staining was diffuse, intense, and readily interpretable, with rare exceptions. All 15 cases of HCC were negative. We conclude that cholangiocarcinoma and metastatic adenocarcinoma from a variety of sites express MOC31; HCC is uniformly negative for this marker. Anti-MOC31 may prove useful in the evaluation of liver neoplasms where primary hepatocellular and adenocarcinoma enter the differential diagnosis; it is not useful in separating primary cholangiocarcinoma from metastatic adenocarcinoma.

Differentiation of primary and metastatic clear cell tumors in the liver by in situ hybridization for albumin messenger RNA

Clear cell neoplasms presenting as metastatic hepatic masses may be difficult to differentiate histologically and immunohistochemically from hepatocellular carcinoma (HCC) with prominent clear cell features, especially in small biopsy specimens. In situ hybridization (ISH) for albumin messenger RNA (mRNA) has been previously shown to be sensitive and specific for the detection of hepatocellular differentiation, but its use for the identification of clear cell HCC has not been previously evaluated. Among 309 cases of hepatocellular carcinoma diagnosed at Mayo Clinic between 1985 and 1998, 30 cases (9.7%) with at least 30% (range, 30%-90%; median 60%) clear cells were studied by ISH for albumin mRNA. In addition, immunohistochemical expression of AFP and polyclonal CEA, serum determination of AFP, and histopathologic analyses of the tumor were done. Forty-two clear cell tumors were used as a control group: 21 metastatic clear cell tumors to the liver (14 renal cell carcinomas and 7 adrenal cortical carcinomas) and 21 primary clear cell tumors of the retroperitoneum (10 renal cell carcinomas, 5 adrenal cortical adenomas, 4 adrenal cortical carcinomas, and 2 ovarian carcinomas). ISH for albumin mRNA was reactive in 28 of 30 cases of clear cell HCC (93%). Clear cell HCC expressed AFP (15 cases; 50%) and polyclonal CEA (19 cases; 63%). Tumors expressed either AFP or polyclonal CEA in 23 cases (77%). Elevated serum AFP was present in 24 of 26 cases (92%). These results indicate that ISH for albumin mRNA is a useful method to distinguish clear cell HCC from other clear cell carcinomas metastatic to the liver and clear cell neoplasms in the retroperitoneum.

An immunohistochemical study of hepatic atypical adenomatous hyperplasia, hepatocellular carcinoma, and cholangiocarcinoma with alpha-fetoprotein, carcinoembryonic antigen, CA19-9, epithelial membrane antigen, and cytokeratins 18 and 19

Eight hepatic atypical adenomatous hyperplasias (AH), 30 hepatocellular carcinomas (HCC) consisting of 11 well-, 13 moderately and six poorly differentiated HCC, and 10 intrahepatic cholangiocarcinomas (CC) were investigated immunohistochemically with anti-alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), CA19-9, epithelial membrane antigen (EMA), and cytokeratins (CK) 18 and 19 antibodies. Immunostaining was regarded as positive when more than 5% of cells were stained. Alpha-fetoprotein was positive, although focally, in five (17%) of 30 HCC but negative in all AH and CC. Carcinoembryonic antigen (polyclonal antibody) did not stain the cytoplasm of all AH and HCC, but stained two (25%) of eight AH and 10 (33%) of 30 HCC in a bile canalicular staining manner. Carcinoembryonic antigen showed intracytoplasmic or luminal border staining in six (60%) of 10 CC. CA19-9 was negative in all AH and HCC, while six (60%) of 10 CC were positive for CA19-9. Epithelial membrane antigen was positive in one (13%) of eight AH, seven (23%) of 30 HCC and in all 10 cases of CC. Cytokeratin 18 was positive in all AH, HCC and CC. Cytokeratin 19 was negative in both AH and HCC, whereas it stained the cytoplasm of tumor cells in all CC diffusely and intensely. These results suggest that immunostaining of AFP, CEA, CA19-9, EMA, CK18 and CK19 are not useful in the differential diagnosis between AH and well-differentiated HCC, and that CK19 is the most suitable reagent for the differential diagnosis between HCC and CC.

Immunohistochemical expression of cytokeratins in intrahepatic cholangiocarcinoma and metastatic adenocarcinoma of the liver

BACKGROUND AND OBJECTIVES

This study was designed to identify a difference in immunostaining that might help to distinguish between primary and metastatic liver neoplasms.

METHODS

We examined immunohistochemical expression of cytokeratins (CKs) 7, 8, 19, and 20 in 12 intrahepatic cholangiocarcinomas (ICCs; 9 of the mass-forming and 3 of the infiltrating type), 25 metastatic colorectal carcinomas (MCCs), and 7 metastatic gastric carcinomas (MGCs) of the liver.

RESULTS

CKs 7 and 19 were expressed in all ICCs of infiltrating type, while each was seen in 7/9 (77.8%) of mass-forming type. CK 7-positive/CK 20-negative was seen in 9/12 (75.0%) of ICCs and in none of the 25 MCCs, while CK 7-negative/CK 20-positive was seen in 1/12 (8.3%) of ICCs and 20/25 (80.0%) of MCCs. No differences were observed between MGCs and ICCs.

CONCLUSIONS

These results suggest that immunohistochemical staining for both CKs 7 and 20 is useful for the differential diagnosis of ICCs and MCCs, whereas phenotypic expression of CKs appears to be different between mass-forming and infiltrating types of ICCs.

Diagnostic implications of albumin messenger RNA detection and cytokeratin pattern in benign hepatic lesions and biliary cystadenocarcinoma

Cytokeratin (CK) patterns and albumin messenger RNA (mRNA) are investigated in 24 patients with benign hepatic lesions (7 patients with focal nodular hyperplasia [FNH], 10 with hepatocellular adenomas [HA], 1 with biliary hamartoma, 4 with biliary cysts, 2 with cystadenomas) and in 8 patients with cystadenocarcinoma, a rare liver malignancy. The lesions and surrounding tissue of the hepatocytic components expressed CK 8 and 18 at immunohistochemistry, whereas the biliary elements evidenced CK 8 and 18 and CK 7 and 19. The albumin mRNA, as detected by in situ hybridization (ISH), revealed different distributions in the hepatocytes of FNH and HA. In the benign biliary lesions, the normal hepatocytes surrounding the tumors expressed albumin mRNA, whereas the biliary structures did not. Interestingly, in the cystadenocarcinomas, albumin mRNA was observed not only in the hepatocytes of residual parenchyma, but also in neoplastic bile duct cells lining the carcinomatous cysts; no signal was identified in the nonneoplastic biliary elements. This indicates that cystadenocarcinomas have a mixed biological phenotype and suggests they could arise either from pluripotent cells or from neoplastic cells that reacquire epigenetic features. Our results suggest two possible diagnostic applications for albumin ISH: on routine sections, it could represent an important tool for distinguishing between cystadenoma and cystadenocarcinoma; and on fine needle biopsy specimens, it could reduce uncertainty between FNH and HA.