Arginase-1: a new immunohistochemical marker of hepatocytes and hepatocellular neoplasms

Distinct Clinicopathologic and Genetic Features of 2 Histologic Subtypes of Intrahepatic Cholangiocarcinoma

Previous studies have identified 2 clinically significant morphologic subtypes of intrahepatic cholangiocarcinoma (ICC) on the basis of anatomic location and/or histologic appearances. Recognizing that these classification schemes are not always applicable practically, this study aimed to establish a novel classification system based on mucin productivity and immunophenotype and to determine the rationale of this classification by examining the clinicopathologic and genetic characteristics of the 2 subtypes defined by this method. We retrospectively investigated 102 consecutive ICC cases and classified them on the basis of mucin productivity and immunophenotype (S100P, N-cadherin, and NCAM). We found that 42 and 56 cases were classified as type 1 and type 2 ICCs, respectively, and only 4 cases were of indeterminate type. Type 1 ICC, generally characterized by mucin production and diffuse immunoreactivity to S100P, arose less frequently in chronic liver diseases and showed higher levels of serum CEA and CA 19-9 than did type 2 ICC, which generally showed little mucin production and exhibited immunoreactivity to N-cadherin and/or NCAM. Type 1 ICC was characterized by several pathologic features, including higher frequencies of perineural invasion and lymph node metastasis. Although the log-rank test demonstrated that type 1 ICC had significantly worse survival, the multivariate Cox regression analysis showed no prognostic significance of this histologic subtype. Genetic analyses revealed that KRAS mutation was significantly more frequent in type 1 ICC, whereas IDH mutation and FGFR2 translocation were restricted to type 2 ICC. In conclusion, the present classification of ICC based on mucin productivity and immunophenotype identified 2 subtypes with clinicopathologic significance.

Combined primary hepatic neuroendocrine carcinoma and hepatocellular carcinoma with aggressive biological behavior (adverse clinical course): A case report

Combined primary hepatic neuroendocrine carcinoma (PHNEC) and hepatocellular carcinoma (HCC) is a very rare malignant hepatic tumor. Its prognosis and histological features are uncertain. Here we report the case of such a tumor in a 70-year-old male Japanese patient with adverse prognosis. The patient underwent a right hepatic lobectomy for a tumor mass that measured 11×10cm in diameter located in the right lobe of the liver, treated with transcatheter arterial chemoembolization (TACE) and percutaneous transhepatic portal vein embolization (PTPE) therapy five weeks before the operation. Histologically, the hepatic tumor was composed of predominantly HCC and admixed with a small part of neuroendocrine carcinoma (NEC). The NEC component was distributed as a collision-type tumor separated by fibrous bands from HCC and the combined-type tumor, focally intermingling with HCC. One month after the surgery, metastasis to abdominal lymph nodes and the lumbar vertebra was detected. Although the additional treatments of systematic chemotherapy and radiation therapy were performed, the patient died 3 months after the initial surgery.

Immunohistochemistry in the Diagnosis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) can be difficult to distinguish from its mimics, including metastatic tumor, benign hepatocellular lesion, and high-grade dysplastic nodule, especially when limited biopsy material is available. Hence, the judicious use of immunohistochemical stains is necessary to establish a correct diagnosis. This article describes advantages and disadvantages of immunohistochemical markers that are most commonly used to distinguish between these lesions. Diagnostic workup of malignant liver mass (HCC and its histologic variants vs metastatic tumor) as well as well-differentiated hepatocellular lesion (well-differentiated HCC vs focal nodular hyperplasia vs hepatocellular adenoma) is also discussed.

Tissue Biomarkers in Hepatocellular Tumors: Which, When, and How

Few tissue markers are currently available to pathologists in the study of hepatocellular tumors. These markers should be used carefully taking into consideration not only morphology but also, and sometimes even more important, the clinical setting where the lesion to be diagnosed had developed. Glypican-3, heat shock protein 70, and glutamine synthetase (GS) are markers currently used, as a single panel, to discriminate the nature of a <2 cm hepatocellular lesion lacking radiological features of hepatocellular carcinoma (HCC) detected in a cirrhotic patient under surveillance. Their use, which can be improved by clathrin heavy chain, is mostly requested on liver biopsy. Hepatocyte paraffin 1, arginase-1, polyclonal carcinoembryonic antigen, CD10, and bile salt export pump are tissue markers used to confirm, at histology, the diagnosis of HCC made by imaging before enrollment for phase III studies on novel anti-HCC drugs. In this setting, pathologists are usually requested a conclusive diagnosis on a liver biopsy of a poorly differentiated, necrotic, enriched in stem-phenotype, carcinoma. Liver fatty acid-binding protein, serum amyloid A, C-reactive protein, prostaglandin D2 synthetase, GS, and β-catenin can be used either on biopsy or surgical specimen to classify hepatocellular adenoma into hepatocyte nuclear factor (HNF-1α) inactivated (steatotic), inflammatory, with dysregulation of sonic hedgehog and prostaglandin pathways, β-catenin mutated, and unclassified.

Immunohistochemical approach for the diagnosis of a liver mass on small biopsy specimens

Well-differentiated hepatocellular carcinoma (HCC) shares overlapping histological features with benign hepatocellular lesions, including hepatocellular adenoma and focal nodular hyperplasia in non-cirrhotic liver, and with high-grade dysplastic nodule in cirrhotic liver. Several metastatic tumors, such as neuroendocrine tumor, renal cell carcinoma, adrenocortical carcinoma, melanoma, and epithelioid angiomyolipoma, can be indistinguishable from HCC on histologic grounds. Since this distinction has important therapeutic implications, judicious use of immunohistochemical markers plays an important role in establishing an accurate diagnosis, especially when limited material of tumor is available on cell block or a small core biopsy. This review describes commonly used immunohistochemical markers used in the diagnosis of HCC, highlighting advantages and disadvantages of each marker, and suggests appropriate immunohistochemical panels for specific clinicopathologic situations.

BSEP and MDR3: Useful Immunohistochemical Markers to Discriminate Hepatocellular Carcinomas From Intrahepatic Cholangiocarcinomas and Hepatoid Carcinomas

We herein examined the immunohistochemical expression of 2 hepatocyte-specific transporters (bile salt export pump [BSEP] and multidrug-resistance protein 3 [MDR3]) in hepatocellular carcinomas (HCCs, n=54), intrahepatic cholangiocarcinomas (n=34), combined hepatocellular and cholangiocarcinomas (n=23), and hepatoid carcinomas originated from extrahepatic organs (n=27) to compare their diagnostic values with those of arginase-1 (ARG1) and hepatocyte paraffin-1 (HepPar-1). BSEP was expressed in 91% of HCCs and MDR3 in 83%. Although their sensitivities were slightly lower than those of ARG1 (96%) and HepPar-1 (93%), the 2 transporters appeared to be more specific for HCCs. ARG1 and HepPar-1 were expressed in intrahepatic cholangiocarcinomas (9% and 6%) and hepatoid carcinomas (22% and 44%, respectively), whereas BSEP and MDR3 were entirely negative in these neoplasms, except for 1 case of BSEP-positive hepatoid carcinoma of the esophagus. The highly specific expression of BSEP and MDR3 in hepatocytes was recapitulated in additional examinations of combined hepatocellular and cholangiocarcinomas, in which the expression of the transporters was restricted to morphologically hepatocellular areas. In contrast, ARG1 and HepPar-1 were also variably positive in areas of biliary or indeterminate differentiation. We also applied BSEP and MDR3 immunohistochemistry to 8 biopsy cases of poorly differentiated primary liver cancer, in which the original diagnosis was not conclusive. The diagnosis of HCC was retrospectively suggested in 2 cases expressing both BSEP and MDR3. In conclusion, given the highly specific expression of BSEP and MDR3 in HCCs, immunohistochemistry for these transporters will be useful not only for determining hepatocellular differentiation in primary liver cancers but also for discriminating HCCs from hepatoid carcinomas.

Expression of Markers of Hepatocellular Differentiation in Pancreatic Acinar Cell Neoplasms: A Potential Diagnostic Pitfall

OBJECTIVES

Pancreatic acinar cell carcinoma (ACC) is a rare tumor that frequently metastasizes to the liver and may present a diagnostic challenge due to its morphologic similarity to hepatocellular carcinoma. We investigated α-fetoprotein (AFP), hepatocyte paraffin antigen 1 (HepPar 1), glypican 3, arginase 1, and albumin messenger RNA (mRNA) in situ hybridization (ISH) in pancreatic neoplasms with ACC differentiation to assess their diagnostic value.

METHODS

AFP, HepPar 1, glypican 3, and arginase 1 immunohistochemical staining was performed on 28 ACCs using a tissue microarray. Albumin mRNA ISH was performed on full-faced sections.

RESULTS

Fifteen tumors were positive for at least one marker. Glypican 3 was positive in seven of 28, AFP in five 28, and albumin mRNA ISH in five of 20. None expressed arginase 1.

CONCLUSIONS

Hepatocellular differentiation markers, including albumin mRNA ISH, may be positive in ACC, but arginase 1 appears to be uniformly negative. Thus, its use may improve the accuracy in distinguishing these neoplasms from hepatocellular carcinoma. If ACC diagnosis is considered, acinar differentiation can be reliably demonstrated by trypsin/chymotrypsin.

Differential proteomic and tissue expression analyses identify valuable diagnostic biomarkers of hepatocellular differentiation and hepatoid adenocarcinomas

The exact discrimination of lesions with true hepatocellular differentiation from secondary tumours and neoplasms with hepatocellular histomorphology like hepatoid adenocarcinomas (HAC) is crucial. Therefore, we aimed to identify ancillary protein biomarkers by using complementary proteomic techniques (2D-DIGE, label-free MS). The identified candidates were immunohistochemically validated in 14 paired samples of hepatocellular carcinoma (HCC) and non-tumourous liver tissue (NT). The candidates and HepPar1/Arginase1 were afterwards tested for consistency in a large cohort of hepatocellular lesions and NT (n = 290), non-hepatocellular malignancies (n = 383) and HAC (n = 13). Eight non-redundant, differentially expressed proteins were suitable for further immunohistochemical validation and four (ABAT, BHMT, FABP1, HAOX1) for further evaluation. Sensitivity and specificity rates for HCC/HAC were as follows: HepPar1 80.2%, 94.3% / 80.2%, 46.2%; Arginase1 82%, 99.4% / 82%, 69.2%; BHMT 61.4%, 93.8% / 61.4%, 100%; ABAT 84.4%, 33.7% / 84.4%, 30.8%; FABP1 87.2%, 95% / 87.2%, 69.2%; HAOX1 95.5%, 36.3% / 95.5%, 46.2%. The best 2×/3× biomarker panels for the diagnosis of HCC consisted of Arginase1/HAOX1 and BHMT/Arginase1/HAOX1 and for HAC consisted of Arginase1/FABP1 and BHMT/Arginase1/FABP1. In summary, we successfully identified, validated and benchmarked protein biomarker candidates of hepatocellular differentiation. BHMT in particular exhibited superior diagnostic characteristics in hepatocellular lesions and specifically in HAC. BHMT is therefore a promising (panel based) biomarker candidate in the differential diagnostic process of lesions with hepatocellular aspect.

Metastases to nasal cavity and paranasal sinuses

The sinonasal cavities are rare locations for metastases. Metastases to these locations are usually solitary and produce similar symptoms to those of a primary sinonasal tumor. Nasal obstruction and epistaxis are the most frequent symptoms. The maxillary sinus is most frequently involved. The most common primary tumor sites to spread to this region originate in the kidney, breast, thyroid, and prostate, although any malignancy could potentially lead to a metastasis to the paranasal sinuses. The patient's prognosis is usually poor because of the fact that the sinonasal metastasis is usually associated with widespread disseminated disease. In the majority of patients, palliative therapy is the only possible treatment option. Nevertheless, whenever possible, surgical excision either alone or combined with radiotherapy may be useful for palliation of symptoms and, rarely, to achieve prolonged survival. This review considers the most interesting cases reported in the literature that presents metastases to the sinonasal cavities. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1847-1854, 2016.

The expression of arginase-1, keratin (K) 8 and K18 in combined hepatocellular-cholangiocarcinoma, subtypes with stem-cell features, intermediate-cell type

AIMS

The WHO classification describes that combined hepatocellular-cholangiocarcinoma, subtypes with stem-cell features, intermediate-cell subtype (CHC-INT) is composed of tumour cells with features intermediate between hepatocytes and cholangiocytes. However, we previously reported that CHC-INT showed a high positive rate of biliary markers, but the expression of hepatocyte paraffin (HepPar)-1 was low. In this study, we examined the expression of other hepatocyte markers, such as arginase-1 (Arg-1), keratin (K) 8 and K18 in CHC-INT in order to examine the utility of pathological diagnosis in CHC-INT.

METHODS

We performed immunohistochemistry (IHC) of Arg-1, K8 and K18 using 32 previously diagnosed as CHC-INT. Immunoreactivity was evaluated with grading from 0 to 4 according to the distribution area of positive cells. The obtained findings of Arg-1, K8 and K18 were compared with those of K7, K19 and HepPar-1.

RESULTS

Out of the 32 cases, 22 (68.8%) cases were positive for Arg-1. Twenty-five (78.1%) were positive for K8. The IHC scores of Arg-1 and K8 were significantly higher than those of HepPar-1, but significantly lower than those of K7 and K19. The K18 expression was widely observed in all cases (100%). The IHC score of Arg-1 and K8 in CHC-INT was intermediate between hepatocellular carcinoma and cholangiocarcinoma.

CONCLUSIONS

Arg-1 and K8 were good markers to identify intermediate cells between hepatocytes and cholangiocytes. These can be useful markers for pathological diagnosis of CHC-INT, which usually has wide histological diversities, in combination with other hepatocytic and/or cholangiocytic markers.

Hepatocellular Carcinoma: Histologic Subtypes

This review discusses the various histologic subtypes of hepatocellular carcinoma (HCC), focusing on their clinical features, pathologic features, immunohistochemical profiles, differential diagnosis, prognosis, and clinical relevance of diagnosis. The WHO recognized variants of scirrhous HCC, fibrolamellar carcinoma, combined HCC-cholangiocarcinoma (HCC-CC), sarcomatoid HCC, undifferentiated carcinoma, and lymphoepithelioma-like HCC are discussed in detail. Other subtypes including clear cell HCC, diffuse cirrhosis-like HCC, steatohepatitic HCC, transitional liver cell tumor, and CAP carcinoma are also reviewed.

Cervical lymph node metastases from remote primary tumor sites

Although most malignant lymphadenopathy in the neck represent lymphomas or metastases from head and neck primary tumors, occasionally, metastatic disease from remote, usually infraclavicular, sites presents as cervical lymphadenopathy with or without an obvious primary tumor. In general, these tumors metastasize to supraclavicular lymph nodes, but occasionally may present at an isolated higher neck level. A search for the primary tumor includes information gained by histology, immunohistochemistry, and evaluation of molecular markers that may be unique to the primary tumor site. In addition, 18F-fluoro-2-deoxyglocose positron emission tomography combined with CT (FDG-PET/CT) has greatly improved the ability to detect the location of an unknown primary tumor, particularly when in a remote location. Although cervical metastatic disease from a remote primary site is often incurable, there are situations in which meaningful survival can be achieved with appropriate local treatment. Management is quite complex and requires a truly multidisciplinary approach. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2374-E2385, 2016.

Comparison of 5 Immunohistochemical Markers of Hepatocellular Differentiation for the Diagnosis of Hepatocellular Carcinoma

CONTEXT

Several immunohistochemical markers are available to establish the diagnosis of hepatocellular carcinoma. Judicious selection is essential to achieve a reliable diagnosis in limited tissue provided by liver biopsy.

OBJECTIVE

To compare the efficacy of 5 hepatocellular markers for the diagnosis of hepatocellular carcinoma across various levels of differentiations.

DESIGN

Immunohistochemistry for hepatocyte paraffin antigen 1 (Hep Par 1), polyclonal carcinoembryonic antigen (CEA), glypican-3, arginase-1, and bile salt export pump transporter was performed in 79 hepatocellular carcinomas, yielding 93 observations (13 well-differentiated [14%], 41 moderately differentiated [44%], and 39 poorly differentiated [42%] tumors).

RESULTS

Arginase-1 and Hep Par 1 had the highest sensitivity for well-differentiated hepatocellular carcinoma, whereas arginase-1 and glypican-3 had the highest sensitivity for poorly differentiated hepatocellular carcinoma. When staining of more than 50% of the tumor was considered a positive result, arginase-1 remained the most sensitive marker for all differentiations, whereas sensitivity for Hep Par 1 in poorly differentiated hepatocellular carcinoma dropped to 30% and that of glypican-3 in well-differentiated hepatocellular carcinoma was 15%. The addition of Hep Par 1 and/or polyclonal CEA to arginase-1 did not lead to an increase in sensitivity for any differentiation. The combined use of arginase-1 and glypican-3 yielded 100% sensitivity for poorly differentiated hepatocellular carcinoma.

CONCLUSION

Arginase-1 was the most sensitive marker in all differentiations of hepatocellular carcinoma. Glypican-3 had high sensitivity for poorly differentiated cases and its combined use with arginase-1 enabled identification of nearly all cases of poorly differentiated hepatocellular carcinoma. Although bile salt export pump transporter has good overall sensitivity, it has a limited role in establishing hepatocellular differentiation when added to a panel of arginase-1 with either glypican-3 or Hep Par 1.

Practical Applications in Immunohistochemistry: Carcinomas of Unknown Primary Site

CONTEXT

-Identification of the site of origin of carcinoma of unknown primary using immunohistochemistry is a frequent requirement of anatomic pathologists. Diagnostic accuracy is crucial, particularly in the current era of targeted therapies and smaller sample sizes.

OBJECTIVES

-To provide practical guidance and suggestions for classifying carcinoma of unknown primary using both proven and new antibodies, as well as targeting panels based on integration of morphologic and clinical features.

DATA SOURCES

-Literature review, the authors' practice experience, and authors' research.

CONCLUSIONS

-With well-performed and interpreted immunohistochemistry panels, anatomic pathologists can successfully identify the site of origin of carcinoma of unknown primary. It is crucial to understand not only the diagnostic uses of the many available antibodies but also the potential limits and pitfalls.

The Applicability of a Human Immunohistochemical Panel to Mouse Models of Hepatocellular Neoplasia

Various immunohistochemical panels are used as aids to distinguish between primary hepatocellular malignancies and metastatic tumors and between benign lesions and carcinomas. We compared the immunohistochemical spectrum of hepatocellular lesions in mice with that of human hepatocellular carcinoma (HCC). Specifically, we compared the staining parameters of 128 murine foci of cellular alteration (FCA) and tumors (adenoma and HCC) from archival tissue blocks of 3 transgenic mouse models (LFABP-cyclin D1, Alb1-TGFβ1, and LFABP-cyclin D1 × Alb1-TGFβ1) with those of archival human HCC (n = 5). Antibodies were chosen according to their published performance and characterization in human hepatocellular tumor diagnosis and included: arginase 1 (Arg1), β-catenin, glutamine synthetase (GS), glypican 3, hepatocyte paraffin 1 (HepPar1), and cytokeratin 19 (CK19). GS was the single best immunostain for identifying hepatocellular tumors in mice, with 100% positive staining. Data showed a trend toward loss of normal function (staining) with Arg1, with a higher percentage of positive staining in FCA than in adenomas and HCC. All FCA lacked murine β-catenin nuclear translocation, which was present in 2 of the 7 adenomas and 22 of the 96 HCC tested. HepPar1 staining was lower than anticipated, except in trabecular HCC (16 of 22 samples were positive). Glyp3 stained very lightly, and only scattered CK19-positive cells were noted (4 of 44 cases of mouse trabecular HCC). Thus, GS appears to be the most useful marker for identifying neoplasia in the transgenic mouse models we tested and should be included in immunohistochemistry assessing hepatocellular neoplasia development.

HepPar-1 and Arginase-1 Immunohistochemistry in Adenocarcinoma of the Small Intestine and Ampullary Region

CONTEXT :HepPar-1 and Arginase-1 are urea cycle enzymes used to distinguish hepatocellular carcinoma from other carcinomas. HepPar-1, but not Arginase-1, is known to be immunoreactive with normal human small intestine.

OBJECTIVES

To better define and compare the immunohistochemical staining patterns of HepPar-1 and Arginase-1 in adenocarcinomas arising in the small intestine, including the ampullary region.

DESIGN

Staining for HepPar-1 and Arginase-1 was performed on 20 nonampullary small intestinal adenocarcinomas and 32 adenocarcinomas from the ampullary region. Ampullary adenocarcinomas were divided into intestinal morphology (15), pancreatobiliary morphology (14), and unclassifiable (3). Nonneoplastic small intestinal mucosa and colorectal adenocarcinomas were used as control groups.

RESULTS

HepPar-1 stained 12 of 20 nonampullary small intestinal adenocarcinomas, with a median of 63% of cells staining in positive cases. It also stained 11 of 15 ampullary carcinomas with intestinal morphology, with a median of 75% of cells staining in positive cases. Two of 14 ampullary carcinomas with pancreatobiliary morphology were positive for HepPar-1. Arginase-1 showed positivity in 2 ampullary region carcinomas and diffuse positivity in 1 duodenal adenocarcinoma. Two of 22 colorectal carcinomas stained for HepPar-1 with none positive for Arginase-1.

CONCLUSIONS

HepPar-1, but not Arginase-1, usually shows positivity in small intestinal adenocarcinomas and ampullary adenocarcinomas with intestinal morphology, but only rarely shows positivity in ampullary adenocarcinomas with pancreatobiliary morphology. HepPar-1 positivity in metastatic adenocarcinoma with intestinal morphology is suggestive of an upper gastrointestinal primary site.

Diagnostic Value of Arginase-1 and Glypican-3 in Differential Diagnosis of Hepatocellular Carcinoma, Cholangiocarcinoma and Metastatic Carcinoma of Liver

BACKGROUND

Hepatocellular carcinoma is the most common primary liver cancer. Pathologic distinction between Hepatocellular Carcinoma (HCC) and adenocarcinoma (Cholangiocarcinoma (CC) and Metastatic Adenocarcinoma (MA)) can be challenging and sometimes requires immunohistochemical panels. Recently, Arginase-1 (ARG-1) and Glypican-3 (GPC-3) have been introduced for differentiation of these tumors.

OBJECTIVES

The aim of this study was to determine the diagnostic accuracy of ARG-1 and GLP-3 in differential diagnosis of liver tumors.

PATIENTS AND METHODS

Eighty-nine formalin-fixed paraffin-embedded tissue blocks including 43 cases of documented HCCs, 19 cases of documented CC, and 27 cases of MA involving the liver (15 colon, 5 stomach, 3 pancreas, 2 gallbladder, 1 duodenum and 1 ampulla of vater) were evaluated for immunohistochemical expression of ARG-1 and GPC-3.

RESULTS

Arginase-1 and GPC-3 demonstrated diffuse staining, as reactivity in > 97% of HCCs, whereas only one (5.3%) and 2 (10.5%) of 19 CC cases show positive staining for GPC-3 and ARG-1, respectively. The expression of both markers in MA showed 6 (22.2%) for ARG-1 and 3 (11.1%) for GPC-3, especially with colorectal origin. Our findings showed a statistically significant difference between ARG-1 and GPC-3 expression in HCC, CC and MA.

CONCLUSIONS

The findings of this study reveal that both ARG-1 and GPC-3 are helpful IHC markers to separate HCC from CC and MA. Furthermore, ARG-1 shows 100% sensitivity and 82.6% specificity for the diagnosis of HCC whereas GPC-3 demonstrated 97.7% sensitivity and 91.3% specificity for the diagnosis of this tumor.

Multidisciplinary perspective of hepatocellular carcinoma: A Pacific Northwest experience

Hepatocellular carcinoma (HCC) is the most rapidly increasing type of cancer in the United States. HCC is a highly malignant cancer, accounting for at least 14000 deaths in the United States annually, and it ranks third as a cause of cancer mortality in men. One major difficulty is that most patients with HCC are diagnosed when the disease is already at an advanced stage, and the cancer cannot be surgically removed. Furthermore, because almost all patients have cirrhosis, neither chemotherapy nor major resections are well tolerated. Clearly there is need of a multidisciplinary approach for the management of HCC. For example, there is a need for better understanding of the fundamental etiologic mechanisms that are involved in hepatocarcinogenesis, which could lead to the development of successful preventive and therapeutic modalities. It is also essential to define the cellular and molecular bases for malignant transformation of hepatocytes. Such knowledge would: (1) greatly facilitate the identification of patients at risk; (2) prompt efforts to decrease risk factors; and (3) improve surveillance and early diagnosis through diagnostic imaging modalities. Possible benefits extend also to the clinical management of this disease. Because there are many factors involved in pathogenesis of HCC, this paper reviews a multidisciplinary perspective of recent advances in basic and clinical understanding of HCC that include: molecular hepatocarcinogenesis, non-invasive diagnostics modalities, diagnostic pathology, surgical modality, transplantation, local therapy and oncological/target therapeutics.

Current concepts in the immunohistochemical evaluation of liver tumors

Immunohistochemistry often plays an important role in the evaluation of liver tumors. Recent advances have established a classification system for hepatocellular adenomas (HCAs) based on morphology, molecular alterations, and immunohistochemistry. Specifically, loss of liver fatty acid binding protein is seen in HNF1α-inactivated HCA, staining with serum amyloid A is seen in inflammatory HCA, and diffuse staining with glutamine synthetase (GS) is seen in β-catenin activated HCA. A panel of immunohistochemical stains including glypican-3 (GPC-3), heat shock protein 70, and GS are useful in distinguishing HCC from non-malignant dysplastic nodules. Immunohistochemistry is also useful to determine whether a liver tumor is of primary hepatocellular or metastatic origin. Recently described markers useful for this purpose include arginase-1, GPC-3, and bile salt export pump. These newer markers may offer superior utility when compared to traditional markers of hepatocellular differentiation such as alpha-fetoprotein, hepatocyte paraffin-1, polyclonal carcinoembryonic antigen, and CD10. This paper will review recent advances in the immunohistochemical evaluation of liver tumors.

Metastatic carcinoma of unknown primary: diagnostic approach using immunohistochemistry

Carcinoma of unknown primary origin (CUP) is one of the 10 most prevalent malignancies. CUP patients in whom a site of origin can be ascribed have better outcomes than those in which the primary tumor remains unidentified. Among the tools available to pathologists in approaching these lesions, immunohistochemistry is a reliable, inexpensive, and widely available resource. New markers continue to emerge, which, in combination with other historically useful antibodies, allow rapid and accurate identification of primary site in an increasing number of cases. This review discusses the approach to the diagnosis of CUP using immunohistochemistry and outlines some of the most useful markers with a particular focus on the utility of lineage-restricted transcription factors, including CDX2, NKX3-1, PAX8, SATB2, TTF-1, and SF1.

Anatomic pathology of hepatocellular carcinoma: histopathology using classic and new diagnostic tools

Hepatocellular carcinoma can be diagnosed on a needle biopsy of the liver; however, uncertainty may arise because of the inherent complexity of liver histology. This article aims to provide practicing pathologists with tools for the approach to mass-directed liver biopsies clinically concerning for hepatocellular carcinoma. The examination of routine hematoxylin-eosin stains and the use of ancillary histochemical and immunohistochemical stains are discussed. Sections reviewing liver carcinoma with biphenotypic differentiation and the challenge of dysplastic nodules are included.

Application of immunohistochemistry in gastrointestinal and liver neoplasms: new markers and evolving practice

CONTEXT

Diagnosis of primary gastrointestinal and liver neoplasms is usually straightforward. Immunohistochemistry is most helpful to differentiate metastatic carcinomas with morphologic similarity and to resolve tumors of unknown origin. Recently, several new markers highly sensitive and specific for primary liver and gastrointestinal tumors have been discovered. Their potential diagnostic application has not been widely appreciated by general practicing pathologists. In addition, a new trend in immunohistochemistry application has started, focusing on assessing predictive markers (such as human epidermal growth factor receptor 2) and mutation-specific markers (v-raf murine sarcoma viral oncogene homolog B V600E) to directly guide clinical management. Practicing pathologists need to be aware of and prepared for this evolving trend.

OBJECTIVES

To summarize the usefulness of several recently discovered immunohistochemical markers in the study of gastrointestinal and liver tumors; to suggest the most current and effective immunohistochemical panels addressing common diagnostic challenges for these tumors; to share practical experience and useful tips for human epidermal growth factor receptor 2 testing in gastric and gastroesophageal junction adenocarcinoma and v-raf murine sarcoma viral oncogene homolog B V600E immunohistochemistry in colorectal carcinoma.

DATA SOURCES

Sources include literature review, and authors' research data and practice experience. The cases illustrated are selected from the pathology archives of the Geisinger Medical Center (Danville, Pennsylvania).

CONCLUSIONS

Application of immunohistochemistry in gastrointestinal and liver tumors continues to evolve. New tumor-specific markers constantly emerge and help pathologists to further improve diagnostic accuracy. Assessment of predictive and prognostic markers by immunohistochemistry in routine pathologic diagnosis is a new trend and will greatly facilitate the advancement of personalized cancer therapy.

Branched chain in situ hybridization for albumin as a marker of hepatocellular differentiation: evaluation of manual and automated in situ hybridization platforms

Albumin, widely recognized as a highly sensitive and specific marker of hepatocellular carcinoma (HCC), is currently unavailable in the diagnostic laboratory because of the lack of a robust platform. In a prior study we detected albumin mRNA in the majority of intrahepatic cholangiocarcinomas using a novel branched chain RNA in situ hybridization (ISH) platform. We now explore the utility of albumin ISH as a marker of hepatocellular differentiation in HCCs, and compare its sensitivity with Hep Par 1 and Arginase-1. We evaluated 93 HCCs and its mimics including neuroendocrine tumors of the gastrointestinal tract (n=31), neuroendocrine tumors of the pancreas (n=163), melanoma (n=15), and gallbladder carcinoma (n=34). We performed ISH for albumin and immunohistochemistry for Hep Par 1 and Arginase-1. Five previously uncharacterized hepatic neoplasms from our files were also evaluated. Immunohistochemistry for Arginase-1 was performed on 59 intrahepatic cholangiocarcinomas. In addition, 43 HCCs evaluated on the manual platform were also examined on the automated instrument. Fifty-five percent of HCCs were moderately differentiated and 39% poorly differentiated. The sensitivity of ISH for albumin was 99%, with 92 of 93 HCCs staining positive for albumin. In contrast to ISH, the sensitivity of immunohistochemistry for Hep Par 1 and Arginase-1 was 84% and 83%, respectively. The sensitivity of albumin for poorly differentiated HCCs was 99%, whereas that for Arginase-1 and Hep Par 1 was 71% and 64%, respectively. Ninety-seven percent of the HCCs showed albumin positivity in >50% of tumor cells using the ISH platform, as compared with 76% and 70% for Hep Par 1 and Arginase-1 immunohistochemistry, respectively. Three of the 5 previously uncharacterized neoplasms were positive for albumin ISH. Automated albumin ISH platform performed equivalently to the manual format, with albumin reactivity in >50% of tumor cells in all 43 cases that were tested on both platforms. All non-HCCs were negative for albumin. All 59 intrahepatic cholangiocarcinomas were negative for Arginase-1. In conclusion, branched chain ISH performed on manual and automated mode is a robust assay for detecting albumin with sensitivity for poorly differentiated HCCs superior to Arginase-1 and Hep Par 1. When interpreted in conjunction with Arginase-1, albumin ISH offers a high level of sensitivity and specificity.

Bile salt export pump: a sensitive and specific immunohistochemical marker of hepatocellular carcinoma

AIMS

Bile salt export pump (BSEP) is a transporter expressed exclusively at hepatic canaliculi and drives bile-salt efflux. Minimal data exist about BSEP expression in tumours. We hypothesized that BSEP immunohistochemistry would be specific for hepatocellular carcinoma (HCC).

METHODS AND RESULTS

Tissue microarrays, including 48 HCC, 41 cholangiocarcinomas and 24 metastatic tumours in liver, were immunostained for BSEP. Expression was compared with common markers of hepatocytic differentiation including CD10, hepatocyte paraffin-1 antigen (HepPar-1), carcinoembryonic antigen, arginase-1 (ARG) and glypican-3 (GPC-3). BSEP expression was assessed in normal tissues. Special attention was given to adrenal gland (normal and neoplasia). BSEP was easy to interpret and showed no background staining. Canalicular expression was seen in all normal livers, but not in other normal tissue. BSEP was 90% sensitive and 100% specific for HCC (canalicular in 33 of 43 positive cases). The sensitivity of ARG was slightly higher, but specificity was slightly lower (94% for both). HepPar-1 was 90% sensitive and 97% specific. CD10, polyclonal carcinoembryonic antigen (pCEA) and GPC-3 all had lower sensitivity (74, 81 and 54%, respectively).

CONCLUSIONS

In malignant tumours in the liver, BSEP marking was 100% specific and 90% sensitive for HCC. The specificity of BSEP for HCC obviates the need to identify a 'canalicular' pattern, which can limit the utility of other canalicular markers.

Immunohistochemistry in undifferentiated neoplasm/tumor of uncertain origin

CONTEXT

Immunohistochemistry has become an indispensable ancillary study in the identification and classification of undifferentiated neoplasms/tumors of uncertain origin. The diagnostic accuracy has significantly improved because of the continuous discoveries of tissue-specific biomarkers and the development of effective immunohistochemical panels.

OBJECTIVES

To identify and classify undifferentiated neoplasms/tumors of uncertain origin by immunohistochemistry.

DATA SOURCES

Literature review and authors' research data and personal practice experience were used.

CONCLUSIONS

To better guide therapeutic decisions and predict prognostic outcomes, it is crucial to differentiate the specific lineage of an undifferentiated neoplasm. Application of appropriate immunohistochemical panels enables the accurate classification of most undifferentiated neoplasms. Knowing the utilities and pitfalls of each tissue-specific biomarker is essential for avoiding potential diagnostic errors because an absolutely tissue-specific biomarker is exceptionally rare. We review frequently used tissue-specific biomarkers, provide effective panels, and recommend diagnostic algorithms as a standard approach to undifferentiated neoplasms.

Hepatic adrenal rest tumor: Diagnostic pitfall and proposed algorithms to prevent misdiagnosis as lipid-rich hepatocellular carcinoma

We present a case of adrenal rest tumor of the liver in which differential diagnosis from lipid rich-hepatocellular carcinoma (HCC) was challenging. The patient was a 50-year-old woman in whom a 3-cm tumorous mass was discovered in segment 7 of the liver during computed tomography evaluation of a uterine leiomyoma. The preoperative diagnosis was HCC, and subsegmental liver resection was performed. The tumor appeared as a well-demarcated golden yellow nodule consisting of clear or partially eosinophilic cells arranged in a trabecular pattern. The initial impression of this lesion was that of clear cell type or lipid-rich type HCC because it stained positive for Hep Par1, but negative for arginase-1 and positive for CD56 which is one of the neuroendocrine markers. The lesion also stained positive for SF-1 and 3β-HSD, both of which are markers of adrenocortical tissue. The final diagnosis was hepatic adrenal rest tumor. Hepatic adrenal rest tumor should be considered in the differential diagnosis of segment 7 tumor. A diagnostic algorithm that includes immunohistochemical staining for CD56 and arginase-1 is to rule out the possibility of lipid-rich HCC.

Arginase-1 and HepPar-1 expression in fine-needle aspiration specimens of primary lung adenocarcinoma

INTRODUCTION

Arginase-1 is a novel immunohistochemical (IHC) marker for hepatocellular differentiation. The purpose of this study was to evaluate the expression of Arginase-1 and HepPar-1 in lung adenocarcinoma to assess the potential value of these markers for diagnosing metastatic lung tumors, especially to the liver in fine-needle aspiration specimens.

MATERIALS AND METHODS

Forty-four cytology specimens of lung adenocarcinoma, obtained by endobronchial ultrasound-guided fine-needle aspiration were retrospectively reviewed. IHC stains for Arginase-1 and HepPar-1 were performed on formalin-fixed paraffin-embedded cell blocks. Tissue from confirmed hepatocellular carcinoma was used as the positive control. TTF-1 IHC stain was performed in all cases.

RESULTS

All 44 lung adenocarcinoma cases (100%) were negative for Arginase-1, whereas HepPar-1 expression was detected in 3 (7%) of lung adenocarcinomas and negative in 41 (93%). The 3 HepPar-1-positive lung adenocarcinoma cases demonstrated positive TTF-1 IHC stain performed on the same cell block. Although both Arginase-1 and HepPar-1 are useful diagnostic IHC markers to differentiate metastatic lung adenocarcinoma from hepatocellular carcinoma, Arginase-1 IHC stain shows better specificity than HepPar-1 does (Arginase-1 specificity 100% and HepPar-1 specificity 93%).

CONCLUSIONS

Arginase-1 IHC can be used in combination with other markers in the workup of metastatic lung adenocarcinoma, especially to the liver.

The Ability to Diagnose Intrahepatic Cholangiocarcinoma Definitively Using Novel Branched DNA-Enhanced Albumin RNA In Situ Hybridization Technology

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) often is a diagnosis determined by exclusion. Distinguishing ICC from other metastatic adenocarcinomas based on histopathologic or immunohistochemical analysis often is difficult and requires an extensive workup. This study aimed to determine whether albumin, whose expression is restricted to the liver, has potential as a biomarker for ICC using a novel and highly sensitive RNA in situ hybridization (ISH) platform.

METHODS

Modified branched DNA probes were developed for albumin RNA ISH. The study evaluated 467 patient samples of primary and metastatic lesions.

RESULTS

Of the 467 samples evaluated, 83 were ICCs, 42 were hepatocellular carcinomas (HCCs), and 332 were nonhepatic carcinomas including tumors arising from the perihilar region and bile duct, pancreas, stomach, esophagus, colon, breast, ovary, endometrium, kidney, and urinary bladder. Albumin RNA ISH was highly sensitive for cancers of liver origin, staining positive in 82 (99 %) of 83 ICCs and in 42 HCCs (100 %). Perihilar and distal bile duct carcinomas as well as carcinomas arising at other sites tested negative for albumin. Notably, 6 (22 %) of 27 intrahepatic tumors previously diagnosed as carcinomas of undetermined origin tested positive for albumin.

CONCLUSIONS

Albumin RNA ISH is a sensitive and highly specific diagnostic tool for distinguishing ICC from metastatic adenocarcinoma to the liver or carcinoma of unknown origin. Albumin RNA ISH could replace the extensive diagnostic workup, leading to timely confirmation of the ICC diagnosis. Additionally, the assay could serve as a guide to distinguish ICC from perihilar adenocarcinoma.

Tubulin β-III: a novel immunohistochemical marker for intrahepatic peripheral cholangiocarcinoma

AIMS

Our recent proteomic study identified tubulin β-III (TUBB3) as a potential tissue marker for intrahepatic cholangiocarcinomas (CCs). This validation study was conducted to see whether or not TUBB3 can serve as a novel immunohistochemical marker for peripheral CCs, using a large cohort (n = 197) covering various liver tumours and premalignant conditions.

METHODS AND RESULTS

Immunostaining using a monoclonal antibody demonstrated TUBB3 expression in 14/28 cases of peripheral CCs (50%), while its expression was significantly less common in perihilar CCs (6/40, 15%) (P = 0.002). No significant difference was identified in clinicopathological features between TUBB3-positive and -negative cases. TUBB3 expression was entirely negative in hepatocellular carcinomas, biliary premalignant lesions (i.e., biliary intraepithelial neoplasias, intraductal papillary neoplasms), peribiliary gland hamartomas (bile duct adenomas), and non-neoplastic biliary epithelium. TUBB3 expression was only focally noted in 2/12 cases of mixed hepatocellular and cholangiocarcinomas (<10% of cancer cells). Compared with other biliary (CK7 and CK19) and malignant markers (p53 and MUC1), TUBB3 was less sensitive but more specific for peripheral CCs. TUBB3 was also expressed in 40% of metastatic colorectal or breast cancers.

CONCLUSIONS

This study revealed that TUBB3 is a moderately sensitive and highly specific tissue marker for discriminating peripheral CCs from other primary liver tumours.

Immunohistochemical Study of Glypican-3 and HepPar-1 in Differentiating Hepatocellular Carcinoma from Metastatic Carcinomas in FNA of the Liver

Hepatocellular carcinoma (HCC) remains a common malignant cancer worldwide, it is considered the fifth most common malignant cancer. On the other hand, metastatic tumors are widespread in the liver , with metastatic adenocarcinoma (MA) constituting the greatest part, therefore differentiation of HCC from MA is a frequent problem facing the pathologist especially in liver fine-needle aspiration biopsies. Evaluating the diagnostic value of glypican-3 (GPC-3) and HepPar-1 immunostaining in differentiating hepatocellular carcinoma from metastatic tumors in liver cell block material. Fourty eight cell blocks prepared from FNA from the liver ( 30 cases HCC, 18 cases metastatic carcinoma in liver) stained by Glypican -3 and HepPar-1 immunohistochemical markers. Glypican-3 was immunoexpressed in 97% of cases of HCC while all cases of metastatic carcinoma were negative. HepPar-1 was expressed in 93% of cases of HCC and 11% of metastatic carcinoma of the liver. In this study the sensitivity of GPC3 in the diagnosis of HCC in cytological material was 96.7% and the specificity was 100% while the sensitivity and specificity of HepPar-1 was 93.3% and 88.9% respectively. Immunohistochemical staining for GPC-3 in cell block material of the liver is highly sensitive and specific and it is a valuable tool capable of differentiating HCC from most of metastatic tumors of the liver.

Caveolin-1 is essential for protecting against binge drinking-induced liver damage through inhibiting reactive nitrogen species

Caveolin-1 (Cav-1) is known to participate in many diseases, but its roles in alcoholic liver injury remain unknown. In the present study, we aimed to explore the roles of Cav-1 in protecting hepatocytes from ethanol-mediated nitrosative injury. We hypothesized that Cav-1 could attenuate ethanol-mediated nitrosative stress and liver damage through regulating epidermal growth factor receptor/signal transducer and activator of transcription 3/inducible nitric oxide synthase (EGFR/STAT3/iNOS)-signaling cascades. Ethanol-fed mice had time- and dose-dependent increases of Cav-1 in serum and liver with peak increase at 12 hours. Compared to wild-type mice, Cav-1 deficiency mice revealed higher expression of iNOS, higher levels of nitrate/nitrite and peroxynitrite, and had more serious liver damage, accompanied with higher levels of cleaved caspase-3 and apoptotic cell death in liver, and higher levels of alanine aminotransferase and aspartate aminotransferase in serum. Furthermore, the results revealed that the ethanol-mediated Cav-1 increase was in an extracellular signal-regulated kinase-dependent manner, and Cav-1 protected hepatocytes from ethanol-mediated apoptosis by inhibiting iNOS activity and regulating EGFR- and STAT3-signaling cascades. In agreement with these findings, clinical trials in human subjects revealed that serum Cav-1 level was time dependently elevated and peak concentration was observed 12 hours after binge drinking. Alcohol-induced liver lesions were negatively correlated with Cav-1 level, but positively correlated with nitrate/nitrite level, in serum of binge drinkers.

CONCLUSIONS

Cav-1 could be a cellular defense protein against alcoholic hepatic injury through inhibiting reactive nitrogen species and regulating EGFR/STAT3/iNOS-signaling cascades.

Arginase-1: a highly specific marker separating pancreatic adenocarcinoma from hepatocellular carcinoma

BACKGROUND

Arginase-1 and HepPar-1 are effective immunohistochemical (IHC) markers for hepatocellular carcinoma (HCC). In this study, we explored the possible efficacy of these stains in diagnosing pancreatic adenocarcinoma (PAD).

STUDY DESIGN

Arginase-1 and HepPar-1 IHC was performed on formalin-fixed, paraffin-embedded fine needle aspiration (FNA) cell blocks (CB) of PAD (n = 46), tissue microarray (TMA) of PAD (n = 33), FNA CB of HCC (n = 44) and TMA of HCC (n = 85). Negative controls without carcinoma were also applied (pancreas CB, n = 7; pancreas TMA, n = 3).

RESULTS

PAD CB demonstrated arginase-1 positivity in 0 of 46 cases and HepPar-1 positivity in 7 of 46 cases (15%). PAD TMA demonstrated arginase-1 positivity in 0 of 33 cases and HepPar-1 positivity in 4 of 33 cases (12%). HCC CB demonstrated arginase-1 positivity in 37 of 44 cases (84%) and HepPar-1 positivity in 32 of 44 cases (72%). HCC TMA demonstrated arginase-1 positivity in 75 of 85 cases (88%) and HepPar-1 positivity in 80 of 85 cases (94%).

CONCLUSION

Both arginase-1 and HepPar-1 are effective IHC markers of hepatocellular differentiation. Arginase-1 demonstrates superior sensitivity and specificity compared with HepPar-1 in the diagnosis of HCC. However, both arginase-1 and HepPar-1 have a low sensitivity and a very high specificity for PAD.

Immunohistochemical detection of arginase-I expression in formalin-fixed lung and other tissues

Arginases are a family of enzymes that convert L-arginine to L-ornithine and urea. Alterations in expression of the isoform arginase-I are increasingly recognized in lung diseases such as asthma and cystic fibrosis. To define expression of murine arginase-I in formalin-fixed tissues, including lung, an immunohistochemical protocol was validated in murine liver; a tissue that has distinct zonal arginase-I expression making it a useful control. In the lung, arginase-I immunostaining was observed in airway surface epithelium and this decreased from large to small airways; with a preferential staining of ciliated epithelium versus Clara cells and alveolar epithelia. In submucosal glands, the ducts and serous acini had moderate immunostaining, which was absent in mucous cells. Focal immunostaining was observed in alveolar macrophages, endothelial cells, pulmonary vein cardiomyocytes, pulmonary artery smooth muscle, airway smooth muscle and neurons of ganglia of the lung. Arginase-I immunostaining was also detected in other tissues including salivary glands, pancreas, liver, skin, and intestine. Differential immunostaining was observed between sexes in submandibular salivary glands; arginase-I was diffusely expressed in the convoluted granular duct cells of females, but was rarely noted in males. Strain specific differences were not detected. In one mouse with an incidental case of lymphoma, neoplastic lymphocytes lacked arginase-I immunostaining, in contrast to immunostaining detected in non-neoplastic lymphocytes of lymphoid tissues. The use of liver tissue to validate arginase-I immunohistochemistry produced consistent expression patterns in mice and this approach can be useful to enhance consistency of arginase-I immunohistochemical studies.

Newly Available Antibodies With Practical Applications in Surgical Pathology

Selected antibodies that have become available in recent years and have applications in diagnostic pathology are discussed. They include antibodies that are organ-related, provide information on cellular differentiation or histogenetic type, have predictive value in tumors, and highlight infective agents. PAX8 (paired box gene 8) is a marker expressed in the lower female genital tract, thyroid, and kidney and their tumors. Napsin A is expressed in the lung and kidney and is an alternative marker for pulmonary adenocarcinoma. Arginase A is a sensitive and specific marker for liver tumors. ERG (Ets-related gene) is an excellent marker for endothelium and vascular tumors as well as prostatic cancer (about 50% of cases). SOX10 (SRY-related HMG box) is expressed predominantly in melanocytic and Schwann cells and the corresponding tumors. DOG1 (discovered on GIST 1) is an excellent marker for gastrointestinal stromal tumor (GIST) and acinic cell carcinoma. OCT3/4 is a pan–germ cell tumor marker, except yolk sac tumor. SALL4 is positive in various types of germ cell tumors, including yolk sac tumor. MUC4 (mucin-related antigen 4) is a sensitive and specific marker for low-grade fibromyxoid sarcoma. Langerin is a specific marker for Langerhans cells and their tumors. SOX11 is a sensitive marker for mantle cell lymphoma. New generation antibodies against anaplastic lymphoma kinase (ALK) are required to reliably demonstrate ALK gene translocation in pulmonary carcinomas. Lack of expression of succinate dehydrogenase B is seen in paragangliomas of the hereditary form and in the pediatric type of GIST. Antibodies against Trepenoma pallidum can facilitate the diagnosis of syphilis, whereas those against SV40 (simian virus 40) are helpful for diagnosis of BK virus infection and progressive multifocal leukoencephalopathy.

Immunohistochemistry in Gastroenterohepatopancreatobiliary Epithelial Neoplasia: Practical Applications, Pitfalls, and Emerging Markers

Immunohistochemistry (IHC) has broad applications in neoplastic gastrointestinal surgical pathology. Although classically used as a diagnostic tool, IHC increasingly provides prognostic and predictive information. This review highlights 11 key uses of IHC (Box 1). Emphasis is placed on specific clinical applications and qualitative aspects of interpretation. Common pitfalls are specifically highlighted. The potential application of emerging markers is discussed in relation to several of the 11 topics. In many instances, an immunostain serves as a surrogate for specific molecular genetic events. Survey of relevant articles forms the evidence basis for this review.

Hepatocellular carcinoma: histologic considerations: pure, mixed, and motley

Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor seen in adults. The histopathologic diagnosis of classic or conventional differentiated HCC is seldom challenging, however, HCC is a particularly heterogeneous tumor. HCC often has a medley of morphologic features that are either challenging to recognize as hepatocellular, or represents components that are of complex histogenesis. This review focuses on the heterogeneous nature of HCC, with discussion of the histologic variants, some of which the clinical significance is unknown. In some cases, a lack of numbers precludes elucidating the clinical significance of these variants. Ultimately, larger studies are needed to determine the diagnostic and prognostic relevance of the phantasmagoria within HCC.

Small heterodimer partner overexpression partially protects against liver tumor development in farnesoid X receptor knockout mice

Farnesoid X receptor (FXR, Nr1h4) and small heterodimer partner (SHP, Nr0b2) are nuclear receptors that are critical to liver homeostasis. Induction of SHP serves as a major mechanism of FXR in suppressing gene expression. Both FXR(-/-) and SHP(-/-) mice develop spontaneous hepatocellular carcinoma (HCC). SHP is one of the most strongly induced genes by FXR in the liver and is a tumor suppressor, therefore, we hypothesized that deficiency of SHP contributes to HCC development in the livers of FXR(-/-) mice and therefore, increased SHP expression in FXR(-/-) mice reduces liver tumorigenesis. To test this hypothesis, we generated FXR(-/-) mice with overexpression of SHP in hepatocytes (FXR(-/-)/SHP(Tg)) and determined the contribution of SHP in HCC development in FXR(-/-) mice. Hepatocyte-specific SHP overexpression did not affect liver tumor incidence or size in FXR(-/-) mice. However, SHP overexpression led to a lower grade of dysplasia, reduced indicator cell proliferation and increased apoptosis. All tumor-bearing mice had increased serum bile acid levels and IL-6 levels, which was associated with activation of hepatic STAT3. In conclusion, SHP partially protects FXR(-/-) mice from HCC formation by reducing tumor malignancy. However, disrupted bile acid homeostasis by FXR deficiency leads to inflammation and injury, which ultimately results in uncontrolled cell proliferation and tumorigenesis in the liver.

Immunohistochemical pitfalls and the importance of glypican 3 and arginase in the diagnosis of scirrhous hepatocellular carcinoma

Scirrhous hepatocellular carcinoma is a rare ill-defined morphological subtype of hepatocellular carcinoma characterized by marked stromal fibrosis. This variant can be difficult to distinguish from intrahepatic cholangiocarcinoma and metastatic adenocarcinoma, especially on needle biopsies. We performed immunohistochemistry for hepatocellular and adenocarcinoma-associated markers on 20 scirrhous hepatocellular carcinoma cases and compared the results with classical hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Scirrhous hepatocellular carcinomas were significantly less likely to be HepPar-1 positive than classical hepatocellular carcinomas (26% and 74%, respectively; P<0.001) and were significantly more likely to express adenocarcinoma-associated markers such as epithelial cell adhesion molecule (63 vs 11%; P<0.001), cytokeratin 19 (26 vs 2%; P<0.001), and cytokeratin 7 (53 vs 2%; P<0.001). At least one of these adenocarcinoma-related markers was positive in 80% of scirrhous hepatocellular carcinoma cases. Glypican 3 and arginase were positive in 79% and 85% of cases of scirrhous hepatocellular carcinoma, respectively; the combined use of these two markers yielded 100% sensitivity for scirrhous hepatocellular carcinoma. In conclusion, the scirrhous morphology, absence of HepPar-1 staining, and frequent positivity with adenocarcinoma-related markers in scirrhous hepatocellular carcinoma can lead to an erroneous diagnosis of adenocarcinoma. Glypican 3 and arginase are the most reliable markers for identifying hepatocellular differentiation in this setting.

Diagnostic Approach to Hepatic Mass Lesions and Role of Immunohistochemistry

This review provides an overview of various hepatic mass lesions and a practical diagnostic approach, including most recent immunohistochemical stains used in clinical practice. A wide variety of benign and malignant lesions present as hepatic masses, and the differential diagnosis varies. In cirrhotic liver, the commonest malignant tumor is hepatocellular carcinoma (HCC), which needs to be differentiated from macroregenerative nodules, dysplastic nodules, and other tumors. The differential diagnosis of lesions in noncirrhotic liver in younger patients includes hepatic adenoma (HA), focal nodular hyperplasia (FNH), HCC, and other primary hepatic neoplasms and metastases. In older populations, metastases remain the most common mass lesions.

The diagnostic value of arginase-1 immunostaining in differentiating hepatocellular carcinoma from metastatic carcinoma and cholangiocarcinoma as compared to HepPar-1

Background

The ability to distinguish hepatocellular carcinoma (HCC) from metastatic carcinoma (MC) involving the liver and cholangiocarcinoma (CC) by immunohistochemistry has been limited by the lack of a reliable positive marker for hepatocellular differentiation. Arginase-1 is a marker for HCC recently described in some literature.

Aim

To examine the immunohistochemical staining of arginase-1 in cases of HCC, MC involving the liver and CC as compared to hepatocyte paraffin antigen -1 (HepPar-1) in an attempt to further define the diagnostic utility of arginase-1 in differentiating these tumors.

Materials and methods

A comparative immunohistochemical study of arginase-1 and HepPar-1expression was performed in 50 HCC cases, 38 cases of MC to the liver from varying sites, 12 cases of CC and 10 specimens of normal liver tissues. The predictive capacity of arginase-1 and HepPar-1 staining was determined using sensitivity, specificity, positive predictive value, and negative predictive value calculations.

Results

All normal liver tissues (no=10), non- neoplastic cirrhotic liver tissues adjacent to HCC (no=42) as well as those adjacent to MC (no= 9) showed diffuse and strong immunostaining for both arginase-1 and HepPar-1. Arginase-1 demonstrated positive immunoreactivity in 42 of 50 (84%) cases of HCC compared with 35 of 50 (70%) for HepPar-1. Only one of 38 (2.6%) cases of MC and one of 12 (8.3%) cases of CC showed positive immunoreactivity for arginase-1. In contrast, HepPar-1 immunoreactivity was detected in 6 of 38 (15.8%) cases of MC and in 2 of 12 (16.7%) cases of CC. Arginase -1 showed a significantly higher sensitivity for HCC diagnosis (84%) compared to HepPar -1(70%) (p=0.016). The specificity of arginase-1 for HCC diagnosis was higher (96%) than that of HepPar -1 (84%); nevertheless, this was not statistically significant (p=0.109). Howerver, the combination of both immunomarkers for the diagnosis of HCC, raised the specificity to 100%.

Conclusion

Arginase-1 immunostaining has a higher sensitivity and specificity than HepPar-1 for HCC diagnosis. Furthermore, the combined use of arginase-1 and HepPar-1 can provide a potentially promising tool to improve the accuracy in distinguishing HCC from metastatic carcinoma and cholangiocarcinoma.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9991436558072434.

Cutaneous metastases from internal malignancies: a clinicopathologic and immunohistochemical review

Skin metastases occur in 0.6%-10.4% of all patients with cancer and represent 2% of all skin tumors. Skin metastases from visceral malignancies are important for dermatologists and dermatopathologists because of their variable clinical appearance and presentation, frequent delay and failure in their diagnosis, relative proportion of different internal malignancies metastasizing to the skin, and impact on morbidity, prognosis, and treatment. Another factor to take into account is that cutaneous metastasis may be the first sign of clinically silent visceral cancer. The relative frequencies of metastatic skin disease tend to correlate with the frequency of the different types of primary cancer in each sex. Thus, women with skin metastases have the following distribution in decreasing order of frequency of primary malignancies: breast, ovary, oral cavity, lung, and large intestine. In men, the distribution is as follows: lung, large intestine, oral cavity, kidney, breast, esophagus, pancreas, stomach, and liver. A wide morphologic spectrum of clinical appearances has been described in cutaneous metastases. This variable clinical morphology included nodules, papules, plaques, tumors, and ulcers. From a histopathologic point of view, there are 4 main morphologic patterns of cutaneous metastases involving the dermis, namely, nodular, infiltrative, diffuse, and intravascular. Generally, cutaneous metastases herald a poor prognosis. The average survival time of patients with skin metastases is a few months. In this article, we review the clinicopathologic and immunohistochemical characteristics of cutaneous metastases from internal malignancies, classify the most common cutaneous metastases, and identify studies that may assist in diagnosing the origin of a cutaneous metastasis.