Printer Friendly

Application of Immunohistochemistry in Gastrointestinal and Liver Neoplasms :New Markers and Evolving Practice.

Immunohistochemistry (IHC) is commonly used in the diagnosis of gastrointestinal (GI) and liver neoplasms to facilitate accurate tumor classification. (1-4) There are two practical goals: One is to confirm a tumor diagnosis by excluding morphologic mimickers or to identify the most reasonable tissue or organ of origin in cases of metastatic carcinoma of unknown primary. (5,6) The other is to provide meaningful prognostic information and even predict responsiveness to standard chemotherapy or novel molecular targeted therapy. (7-10) In the last 5 to 6 years, several new sensitive and specific markers with proven diagnostic value have become available for pathologists to better address these goals. The purpose of this review is to discuss practical applications of these new markers in the context of common problematic issues encountered in the routine diagnosis of

GI tract and liver tumors. We limited our scope to include mainly tumors of epithelial cell origin and will not emphasize mesenchymal tumors, with the exception of GI stromal tumors (GISTs) and tumors of lymphoid origin.

It is noteworthy that assessment of prognostic and predictive markers by IHC in GI tumors has become increasingly popular. (7) Microsatellite instability (MSI) in colorectal carcinoma (CRC), (11,12) human epithelial growth factor receptor 2 (HER2) in gastric and gastroesophageal junction (GEJ) adenocarcinoma, (8-10) and even Ki-67 in neuroendocrine tumors (NETs) (13,14) are some familiar examples. Currently, not only are pathologists depending on IHC results for diagnosis, but our clinical colleagues have also become interested in knowing the results before they start to formulate the best management plan for individual patients. In a sense, this has begun a new trend to transform IHC from a traditional qualitative assay most useful in distinguishing tumor types to a quantitative clinical test whose result is essential for clinical decision making. With rapid advances in our understanding of molecular and genetic mechanisms of carcinogenesis and a continuous push for personalized cancer therapy, it is highly likely that this trend will rapidly progress. As practicing pathologists, it is our clinical responsibility to be vigilant in overseeing all aspects of IHC to ensure test precision and result accuracy.

LIVER

The most common primary tumors of epithelial origin in liver are hepatocellular carcinoma (HCC) (15) and cholangiocarcinoma (CCA) (16) in adults, and hepatoblastoma (17) in young children. Hepatocellular adenoma (HCA) is a relatively rare benign tumor and must be distinguished from HCC and other benign nonneoplastic hepatic lesions. (18) Metastatic carcinomas are common in the liver. Differentiating them from primary liver tumors can pose a real diagnostic challenge for pathologists.

HEPATOCELLULAR CARCINOMA

Based on classic morphologic features, most HCCs can be easily recognized on hematoxylin-eosin sections. However, many types of benign or malignant tumors may share morphologic similarities. Some of the most notorious mimickers of HCC include adrenocortical carcinoma, renal cell carcinoma, clear cell sarcoma, melanoma, large cell neuroendocrine carcinoma, and angiomyolipoma. (19-21) In addition, poorly differentiated HCC and some HCC variants may be difficult to discern based on morphology alone. (22) In these circumstances, IHC is not only helpful but necessary for accurate diagnosis. In our experience, the most effective IHC approach to address these problematic issues is to positively confirm hepatocellular differentiation in the tumor cells in conjunction with various tumor-specific markers (covered in other review articles in this 2-part special IHC series of articles) to exclude possible mimickers. Table 1 lists a recommended panel of IHC markers along with their reported sensitivities and specificities for diagnosing HCC. The top three markers are preferable because they show a cytoplasmic expression pattern that is easily recognizable, even in small biopsies with disrupted architecture or in cytologic specimens. The other markers are useful supplements to increase sensitivity and specificity. Within the panel, arginase 1 (ARG1) (19,23-27) is a newly described marker with promising performance.

ARG1

ARG1 is a binuclear manganese metalloenzyme involved in the urea cycle. It catalyzes the hydrolysis of arginine to ornithine and urea. (28) Recent studies have clearly demonstrated that it is a great marker for hepatocellular differentiation. (19) Compared with hepatocyte paraffin 1 (HepPar1) and glypican 3 (GPC3), it shows better sensitivity and specificity. (23-27) It is also positive in hepatoblastoma. So far, only rare cases of non-HCC carcinomas have been reported to be immunoreactive to ARG1. (19,26,27) To the best of our knowledge, there has not been any report of ARG1 expression in hepatoid carcinoma, a rare tumor from extrahepatic sites (mostly stomach, pancreas, and uterus) that shows hepatocellular differentiation. (29-33) In our experience, ARG1 is best used together with either HepPar1 or GPC3 to increase diagnostic sensitivity and specificity for HCC. Figure 1, a and b, show staining patterns of HepPar1 and ARG1 in a needle biopsy specimen of HCC. When all 3 markers are used simultaneously, they can identify almost all HCCs, including rare variants. (22) However, caution is still warranted when the combination of these markers is used to differentiate metastatic carcinomas from HCC, particularly hepatoid carcinoma. In difficult scenarios, a distinction between primary HCC and metastasis has to be made on clinical grounds based on a patient's history and an imaging survey of most suspicious sites.

HCC VARIANT WITH UNUSUAL IHC STAINING PROFILE

Scirrhous HCC is a rare morphologic variant, composed of less than 5% of HCCs. (34) It is characterized by marked stromal fibrosis, subcapsular location, multinodularity, and changes in clear cells, with preserved intratumoral portal tracts. It also shows an unusual IHC phenotype. Most of the tumors are negative for HepPar1 and positive for cytokeratin 7 (CK7), CK19, and epithelial cell adhesion molecule (EPCAM), making it difficult to distinguish from intrahepatic CCA (IHCCA) and metastatic adenocarcinoma. It is supposed to have a better prognosis than IHCCA. (35) Recently, Krings et al (22) studied 20 such tumors and found that 85% were positive for ARG1 and 79% were positive for GPC3, whereas only 26% were positive for HepPar1; 53% of the tumors were also positive for CK7, and 26% were positive for CK19.

Fibrolamellar HCC is also a variant of HCC with a distinct morphology and characteristic clinicopathologic features. (36) Unlike most conventional HCCs, the tumor cells are often positive for CK7 and embedded in the dense fibrosis of a noncirrhotic liver. (37,38) Sometimes it can be challenging to distinguish fibrolamellar HCC from metastatic tumor, epithelioid hemangioendothelioma, or IHCCA, particularly in small-needle biopsy specimens. (38) It is helpful to confirm the diagnosis by demonstrating expression of hepatocellular differential markers. Recently, it was found that most tumors also show immunoreactivity to CD68 in an antibody-dependent fashion. (39) The positive rate is higher when the KP-1 clone is used, compared with other clones. (3) This unique finding is also useful in practice to differentiate fibrolamellar HCC from conventional HCC, which is important for prognostic indication. (36)

HEPATOBLASTOMA

Hepatoblastoma is the most common primary liver neoplasm in children younger than 5 years. (17) Morphologically, it is usually composed of embryonal and fetal hepatocyte-like cells with or without a mesenchymal component, (40) although in rare cases a purely fetal-type hepatoblastoma may be difficult to distinguish from HCC. A recent study of immunophenotypes of the tumor revealed that high-mortality group AT hook 2 (HMGA2) is usually positive in hepatoblastoma cells, as are GPC3 and [beta]-catenin. (41) Interestingly, although HMGA2 appears to be positive in all components, GPC3 is more likely to be positive in the fetal component, and [beta]-catenin positivity is mainly seen in the embryonal component. (41) The same study also showed that HMGA2 was positive in about 40% of HCCs developed in patients younger than 30 years and was seldom positive in HCCs from older patients. (41,42) The clinical significance of this finding is still elusive. In our experience, ARG1 is also positive in hepatoblastoma cells, particularly in the fetal component. Figure 1, c and d, show examples of HepPar1 and ARG1 staining in a case of hepatoblastoma.

HEPATOCELLULAR ADENOMA

Hepatocellular adenoma is a relatively rare benign tumor of the liver. (18) Recent studies have suggested a molecular classification system that identifies 4 major subtypes (43,44): hepatocyte nuclear factor 1 alpha (HNF1a)-mutated HCA (30%-35%); b-catenin-mutated HCA (10%-15%); inflammatory HCA (50%); and unclassified (roughly 10%). Within inflammatory HCAs, 10% of tumors may also be [beta]-catenin mutated. Identification of [beta]-catenin-mutated HCA is important because these tumors show a strong association with risk of HCC. Although some unique morphologic features may be found in certain subtypes, a set of 4 or 5 IHC markers is needed for accurate classification. (18,44) A summary of these markers and their staining patterns in HCA subtypes is listed in Table 2.

Differentiating inflammatory HCA from focal nodular hyperplasia, a nonneoplastic condition related to aberrant vascular proliferation, sometimes can be challenging on a small biopsy. It has been noted that focal nodular hyperplasia usually shows a unique geographic pattern of glutamine synthetase stain and is consistently negative for serum amyloid A protein (SAA) and C-reactive protein (CRP). (17,44,45) On the contrary, inflammatory HCA is usually negative for glutamine synthetase (diffuse positivity seen in tumors with [beta]-catenin activation) and positive for SAA and CRP. A caveat is that the staining patterns may be difficult to interpret when lesional tissue is small or when not enough normal liver tissue is present to compare.

Another practical challenge in diagnosing HCA is to differentiate it from well-differentiated HCC. (46) A number of studies have suggested panels of IHC markers to help in this distinction. (46,47) Table 3 lists some of the most commonly used IHC markers for this purpose. In addition, reticulin stain is also helpful in revealing the abnormal trabecular pattern in HCC. Some pathologists like to use endothelial markers, such as CD34, to illustrate thickened trabeculae. In our experience, these markers generally have low sensitivity or specificity for HCC, and one has to be cautious not to rely solely on them for the diagnosis. It is noteworthy that the term well-differentiated hepatocellular neoplasm of uncertain malignant potential (HUMP) has been proposed by some experts to describe HCA-like lesions with atypical features. (48,49) However, at present this is just an evolving concept. There has been no consensus on any specific diagnostic criteria.

CHOLANGIOCARCINOMA

The practical challenge in the diagnosis of IHCCA is to distinguish it from metastatic adenocarcinomas from various sites. In most cases this can be resolved quite effectively with the help of IHC and a detailed clinical history. A list of tumor-specific markers that are commonly used for this distinction is summarized in Table 4. However, differentiating IHCCA from metastatic pancreatic ductal adenocarcinomas or adenocarcinoma from the upper GI tract can be extremely difficult, if not impossible. Even IHC can offer little help because of the lack of tissue-specific markers due to the close relationship of these anatomic sites in the embryonic and fetal development process. Interestingly, a recent study by Lok et al (50) showed that a panel of nonconventional markers (placental S100 [S100P], von Hippel-Lindau tumor suppressor [pVHL], mucin 5AC [MUC5AC], and CK17) may offer more help than anyone would anticipate. They studied the staining patterns in 41 IHCCAs and 60 pancreatic ductal adenocarcinomas and identified a specific pattern ([S100P.sup.-]/[pVHL.sup.+]/[MUC5AC.sup.-]/ [CK17.sup.-]) essentially indicative of IHCC, whereas two other patterns ([S100P.sup.+]/[pVHL.sup.-]/[MUC5AC.sup.+]/[CK17.sup.+] and [S100P.sup.+]/ pVHL-/MUC5AC-/[CK17.sup.+]) were more suggestive of pancreatic ductal adenocarcinoma. The IHCCA-specific pattern picked up almost 60% (24 of 41) of tumors tested. These results are quite intriguing. However, the number of cases examined was still very small. A thorough validation in a large number of cases is necessary to establish its diagnostic utility.

GI TUMORS

The GI tract is a large organ system with complex tissue composition. Histologically, the most common primary tumors of epithelial origin are adenocarcinoma and NETs. (51) Some tumors may show dual differentiation, particularly when they exhibit poorly differentiated or undifferentiated morphology. Immunohistochemistry is helpful and often necessary to confirm the diagnosis. In addition, more and more frequently, IHC detection of Ki-67 is routinely performed in NETs to calculate proliferative index and to predict the aggressiveness of these tumors. (52) Other IHC applications focusing on assessment of predictive or prognostic markers in GI tumors have also been gaining popularity. (7-12) Currently, these tests include HER2 in gastric and GEJ adenocarcinomas, and MSI in CRCs, with the most recent development of the mutation-specific IHC marker vraf murine sarcoma viral oncogene homolog B (BRAF) V600E. (53-55) Nevertheless, in daily practice a major application of IHC remains to help resolve problematic diagnostic issues, such as distinguishing a possible metastatic carcinoma from an adjacent organ system or, rarely, a carcinoma of unknown primary involving the GI tract. In this regard, IHC markers highly sensitive and specific for GI tumors are potentially of help. A set of IHC markers is routinely used to facilitate the distinction. These include CK7, CK20, villin, caudal type homeobox 2 (CDX2), mucin core proteins (MUCs), and others. (56) Recently, two new markers were added to the list, and their enhanced ability to further improve diagnostic accuracy has been gradually appreciated.

CADHERIN 17

Cadherin 17 (CDH17) is also known as liver-intestine cadherin because it was originally discovered as a novel calcium-dependent cell adhesion molecule expressed in the liver and intestine of rats. (57,58) In humans its distribution is actually limited to the duodenum, jejunum, ileum, colon, and part of the pancreatic duct. It is believed to function as an intestinal peptide transporter. (58,59) Its clinical utility in diagnosing GI tumors was only recognized recently. (60-62) The combined data indicate that positive CDH17 immunoreactivity is most commonly seen in colorectal adenocarcinomas (up to 96%) and a significant portion of gastric, pancreatic, and biliary adenocarcinomas (25%-50%). It is rarely found in adenocarcinomas from outside of GI tract (1%-10%). Interestingly, although CDH17 is transcriptionally regulated by CDX2, some authors found it to be slightly more sensitive and specific than CDX2 in identifying colorectal adenocarcinomas. (60,62) Recently, we also studied CDH17 immunoreactivity in a large number of tumors derived from various organ systems. (63) Not only did our data further confirm the reported findings, they also demonstrated its usefulness in diagnosing CRC variant with poorly differentiated or undifferentiated morphology, such as medullary carcinoma, which characteristically lacks expression of conventional intestinal differential markers, such as CK20 and CDX2. CDH17 has also been reported as a sensitive marker for intestinal metaplasia, and thus helpful for histologic diagnosis of early Barrett esophagus. (64-66) Recently, CDH17 has also been studied as a potential prognostic marker in GI and pancreatobiliary carcinomas; however, its clinical implication has not been well established. (67,68)

SPECIAL AT-RICH SEQUENCE BINDING PROTEIN 2

Special AT-rich sequence binding protein 2 (SATB2) belongs to a family of nuclear matrix-associated transcription factors that function as epigenetic regulators of gene expression in a tissue-specific manner. (69-72) Studies have shown that SATB2 carries out a wide spectrum of biologic functions. It is a transcriptional activator of immunoglobulin i expression. (70) It also regulates neuronal and osteoblast differentiation. (69) Haploinsufficiency of the SATB2 gene is associated with cleft palate syndrome in humans. (71) However, the role of SATB2 in the GI tract is still elusive. Recently, Magnusson et al (73) found that SATB2 immunoreactivity was restricted to the glandular lining cells of the human lower GI tract, including appendix, colon, and rectum, and a subset of neuronal cells in the cerebral cortex and hippocampus. Some lymphocytes and cells lining the seminiferous ducts and epididymis also showed weak to moderate immunoreactivity. All other tissue types tested were negative. They also studied SATB2 expression in a large number of human carcinomas. Positive nuclear stain was found in 1336 of 1558 primary colon adenocarcinomas (86%) and 205 of 252 metastatic carcinomas of the colon (81%). (73) Within the noncolonic carcinomas, weak positive immunoreactivity was found in 6 of 147 breast adenocarcinomas, 3 of 53 lung adenocarcinomas, 5 of 153 ovarian carcinomas, 1 of 15 cholangiocarcinomas, and 5 of 9 sinonasal carcinomas. Upper GI carcinomas and pancreatic adenocarcinomas were usually negative for SATB2. (73) We recently also studied SATB2 expression in a large number of tumors derived from various organs. (63) Our results confirm that SATB2 is a highly sensitive and specific marker for adenocarcinomas of the colon and rectum, with a diagnostic sensitivity of 97% (121 of 125 cases) in CRCs. Interestingly, we also found that SATB2 immunoreactivity was seen in a significant number of medullary carcinomas of the colon.

In addition to diagnostic utility, recent reports also indicate a prognostic value of SATB2 in CRCs. (74,75) High SATB2 expression was associated with good prognosis in colon cancer and might modulate sensitivity to chemotherapy and radiation, whereas reduced expression of SATB2 in colorectal adenocarcinomas was found to be associated with poor prognosis, including tumor invasion, lymph node metastasis, and distant metastasis.

POTENTIAL ROLE OF SATB2 IN DIFFERENTIATING ADENOCARCINOMA OF THE UPPER AND LOWER GASTROINTESTINAL TRACT

Compared with CDH17 and CDX2, SATB2 immunoreactivity is much more selective for CRC and is rarely seen in carcinomas of the esophagus and stomach. Whether SATB2 can also help to differentiate a primary small intestinal adenocarcinoma from metastatic CRC involving the small intestine has not been formally tested. This may be a practical diagnostic challenge, and currently no specific IHC markers can offer resolution. (56,76) We recently examined SATB2 immunoreactivity in 5 primary small intestinal adenocarcinomas and found that 3 were negative. The other 2 tumors with positive immunoreactivity were from the distal ileum, where the normal small intestinal mucosa adjacent to tumors was also positive for SATB2. In contrast, all 4 metastatic colonic carcinomas involving the small intestine showed positive immunoreactivity to SATB2. These preliminary results are intriguing and suggest that SATB2 may be useful in distinguishing adenocarcinomas from the small and large intestine. However, a couple of caveats warrant caution. First, the differential capacity is dependent on whether or not SATB2 immunoreactivity is present in the normal small intestinal mucosa in the same region where the tumor occurs. Second, SATB2 expression may be down-regulated or completely lost in some colonic adenocarcinomas with aggressive behavior; a comparison with the expression profile of the original tumor may be recommended.

SATB2 AND CDH17 IN DIAGNOSIS OF MEDULLARY CARCINOMA OF THE COLON

Medullary carcinoma of the colon is a distinct variant of colonic adenocarcinoma. (77,78) It usually occurs in elderly patients, more frequently in women than men (2:1 ratio), and often presents as a large mass in the right colon, especially in the cecum. Histologically, the tumor is characteristic for a number of features, including poorly differentiated or undifferentiated morphology, pushing border invasion, markedly increased intratumoral lymphocytosis, and peritumoral Crohn-like lymphoid reaction. Molecular pathogenically, almost all tumors are MSI with deficiency in mismatch repair proteins, predominantly a lack of MutL homolog 1 (MLH1)/postmeiotic segregation increased 2 (PMS2) expression due to MLH1 promoter hypermethylation. (79,80) Like most MSI colon adenocarcinomas, despite high tumor stages and grades, the prognosis in terms of lymph node and distant metastasis is more favorable compared with microsatellite-stable poorly differentiated adenocarcinomas or neuroendocrine carcinomas of the large intestine. Immunohistochemically, the tumor is also unique. Unlike conventional colorectal adenocarcino mas, medullary carcinoma of the colon frequently lacks CDX2 and CK20 expression. (81-83) Instead, it may express markers not commonly associated with CRCs, such as CK7 and calretinin. (83) Given these unusual features, an accurate diagnosis of this tumor can be quite challenging, particularly in a metastatic setting.

Recently we studied the diagnostic utility of SATB2 and CDH17 in a cohort of 18 medullary carcinomas of the colon. (63) We found that CDH17 was positive in 16 of 18 cases (89%), and SATB2 was positive in 16 of 18 cases (89%). Interestingly, the 2 CDH17-negative cases were positive for SATB2, and the 2 SATB2-negative cases were positive for CDH17. Nearly all positive cases showed a diffuse and strong staining pattern (Figure 2). In stark contrast, only 5 of 18 cases (25%) were focally positive for CK20, and 5 of 18 cases (27%) were convincingly positive for CDX2. Our data demonstrate the usefulness of CDH17 and SATB2 in diagnosing medullary carcinoma of the colon. They also suggest that the combined use of the two markers may increase diagnostic sensitivity. Figure 2, a and b, demonstrate staining patterns of SATB2 and CDH17 in a medullary carcinoma of the colon, respectively.

SATB2 AND CDH17 IN THE DIAGNOSIS OF GI NETS

The GI tract is a common site for NETs to develop. Most GI NETs are well differentiated, and their biologic behavior is primarily dependent on anatomic location, tumor size, and mitotic counts or Ki-67 proliferative index. (13) Clinically, it is not uncommon to encounter metastases to lymph nodes and liver even before the primary NET is big enough to be recognized by conventional imaging studies. It is therefore highly desirable to have GI-specific markers to help diagnose and differentiate other NETs, such as those from pancreas or lung. On the other hand, primary high-grade neuroendocrine carcinomas of the GI tract are relatively rare. (84) When such a tumor is encountered, it is important to exclude the possibility of metastasis from a small cell carcinoma of the lung, where these tumors most commonly occur. The diagnostic utility of IHC in distinguishing NETs from various organ systems has been extensively studied. (85,86) However, very little is known about the usefulness of SATB2 and CDH17 in this setting. One report demonstrated that CDH17 immunoreactivity was present in 100% of well-differentiated NETs of the small intestine and appendix, whereas CDX2 immunoreactivity was present only in 74% and 90% of cases, respectively. A minority of pancreatic endocrine tumors (3 of 26 cases; 12%) and bronchial carcinoid tumors (12 of 50 cases; 24%) were also immunoreactive to CDH17 but were all negative for CDX2. (62) These findings suggest that CDH17, compared with CDX2, is more sensitive but less specific in well-differentiated GI NETs. There has not been any published study on SATB2 expression in NETs. However, data presented in a poster from the 2013 United States and Canadian Academy of Pathology meeting showed that SATB2 immunoreactivity was seen in most well-differentiated NETs of hindgut origin. (87)

We recently examined CDH17 and SATB2 immunoreactivity in 158 well-differentiated NETs from various anatomic sites (data not shown) and found that both markers are highly selective for GI NETs. Figure 3 shows examples of CDH17 and SATB2 immunostaining patterns in a well-differentiated NET of the rectum metastasizing to liver. Although our preliminary data on CDH17 immunoreactivity are similar to the published results, the data on SATB2 immunoreactivity are more interesting. We found that positive SATB2 immunoreactivity is seen in most NETs from the appendix, colon, and rectum but is rarely seen in NETs from the stomach, duodenum, pancreas, or lung. Taken together, in our experience both CDH17 and SATB2 are potentially useful markers for diagnosing GI NETs, and SATB2 seems more specific for NETs from the lower GI tract. In practice, one should consider using these new markers together with CDX2 to maximize sensitivity and specificity for GI NETs.

SUCCINATE DEHYDROGENASE-DEFICIENT GIST

Succinate dehydrogenase (SDH)-deficient GIST has been recognized as a unique variant with characteristic clinicopathologic features. (88-90) It tends to occur in young female patients, with an exclusively gastric location. In fact, a great majority of pediatric GISTs and all GISTs that occur in Carney triad and Carney-Stratakis syndrome are found to be in this category. Histologically, they show a predominantly epithelioid morphology and often a plexiform growth pattern. They have a tendency to be associated with multifocal or metachronous disease. They usually show an indolent biologic behavior and may not follow the risk stratification rule (based on size and mitosis) for conventional GISTs. From a clinical perspective, it is important to recognize this variant because of its absence of KIT (CD117) or platelet-derived growth factor receptor mutations and its primary resistance to imatinib therapy. The genetic pathogenesis of these tumors is complex because of the fact that multiple subtypes of SDH may be affected. (88) However, from a diagnostic perspective only one specific IHC assay for succinate dehydrogenase B (SDHB) is necessary and sufficient to identify all SDH-deficient GISTs. (88,89) The complete absence or a significant reduction of SDHB immunoreactivity in tumor cells essentially confirms the diagnosis. (91)

HER2 TESTING IN GASTRIC AND GEJ ADENOCARCINOMA

HER2 is an important driver of tumorigenesis in several solid tumors. (92) For many years, anti-HER2 targeted therapy has been effective in the treatment of breast carcinomas with HER2 gene amplification. (93) A recent clinical trial also demonstrated that trastuzumab, an anti-HER2 agent, could prolong survival in patients with HER2-positive gastric or GEJ adenocarcinoma. (94) This has started a new era of HER2 testing in these GI tumors. A number of excellent review articles were published in the last 2 years to provide comprehensive background knowledge and up-to-date practical guidance on HER2 testing and scoring in gastric and GEJ carcinomas. (8-10) To avoid repetition here, we simply point out a couple of the most important practical issues that may help to ensure accurate and consistent HER2 testing results. First, specific training is required before a pathologist can embark on HER2 testing in gastric and GEJ cancer. (8) This should be required regardless of his or her previous experience with HER2 testing in breast cancer, because significant differences in staining pattern and scoring criteria exist between the two tumors. Secondly, due to HER2 heterogeneity in gastric and GEJ adenocarcinomas, it is preferred to perform the test on resection specimens whenever possible; when an in situ hybridization test is performed to examine gene amplification in IHC 2+ samples, it is most helpful to use IHC-stained sections as a guide to locate the same area of interest for counting the in situ hybridization signals. The overall HER2-positive rate in diffuse-type gastric or GEJ adenocarcinoma is lower (5%) compared with intestinal type (up to 30%). (8-10,95) It may be worth the effort to perform in situ hybridization to confirm an IHC 3+ result, particularly if a signet ring cell carcinoma is involved. We have noticed a peculiar false-positive circumferential membranous staining pattern in some of the signet ring cell carcinomas tested. With regard to in situ hybridization interpretation, HER2 copy number equal to or greater than 6 should be considered as positive for amplification regardless of HER2/chromosome enumeration probe 17 ratio. (8)

BRAF V600E IHC IN CRC

BRAF represents one of the most frequently mutated protein kinase genes in human tumors. (96) It is found in melanoma, papillary thyroid carcinoma, ovarian serous tumors, CRCs, gliomas, hepatobiliary carcinomas, and hairy cell leukemias. (97-101) In CRC, the most common mutation is BRAF V600E. Currently, the mutation is tested in CRC mainly for two purposes. BRAF V600E mutation in MSI CRCs can virtually exclude Lynch syndrome, and mutation-positive tumors are resistant to anti-epithelial growth factor receptor therapy. (53,54) Although it has been shown that BRAF V600E mutation predicts a poor prognosis in right-sided microsatellite-stable CRC, this prognostic indication has not been widely explored clinically. (102)

Traditionally, BRAF mutation is detected by DNA sequencing or polymerase chain reaction-based mutation detection methods. Recently, antibodies specific to BRAF V600E have been developed, and their use in IHC on formalin-fixed, paraffin-embedded tumor tissue has become popular. (53-55,97,98,100-103) Currently, 2 antibodies are commercially available. VE1 is the most commonly used antibody clone and is recommended because of its high sensitivity and specificity. (104)

At present, BRAF V600E IHC has not been widely used in diagnostic laboratories. However, several recent publications have shown promising results using clinical samples. (53-55,97,98,100-104) It seems that a new trend of using IHC as screening test for BRAF V600E mutation in CRC has evolved. In fact, some authors have proposed incorporating BRAF V600E IHC into the current algorithm for universal screening of CRC for Lynch syndrome. (53-55,100-103)

However, from a technical perspective, BRAF V600E IHC still has some issues to be ironed out before it can be deployed to routine clinical labs. Since its debut there have been some negative comments in the literature regarding the sensitivity and specificity of the assay for clinical use. (105) This concern no longer exists in the most recently published data, which indicate that BRAF V600E IHC is a sensitive and reliable assay, generating results that correlated well with those from molecular detection methods. (53,54,101-103) It is most likely that optimizing the staining protocol has contributed to the recent improvement of the assays performance. Nevertheless, it is our experience that even with an ideal staining protocol, the cytoplasmic staining intensity in BRAF V600E-mutated tumor samples may still vary significantly, ranging from weak to strong. Background nonspecific stain, particularly a peculiar nuclear staining, is common in normal mucosa as well as nonmutated tumor cells. These variables may cause significant problems in accurately interpreting the staining results. Therefore, specific training for pathologists and an appropriate quality assurance program with prospective validation are absolutely needed before the assay can be widely used.

Please Note: Illustration(s) are not available due to copyright restrictions.

CONCLUDING REMARKS

As the new era of genomic medicine unfolds, personalized cancer therapy will become a reality. This will require a new standard of diagnostic accuracy and precision. Immunohistochemistry as an integral component of the practice of diagnostic pathology will continuously evolve to help us meet the new challenge. As practicing pathologists, it is our responsibility to lead this evolution and to ensure the best practice of IHC for patient care.

References

(1.) Geller SA, Dhall D, Alsabeh R. Application of immunohistochemistry to liver and gastrointestinal neoplasms. Arch Pathol Lab Med. 2008; 132(3):490-499.

(2.) Lin F, Wang HL. Pancreas and ampulla. In: Lin F, Prichard JW, Liu H, Wilkerson M, Schuerch C, eds. Handbook of Practical Immunohistochemistry Frequently Asked Questions. New York, NY: Springer; 2011:367-388.

(3.) Chu PG, Weiss LM. Tumors of the digestive system. In: Modern Immunohistochemistry. New York, NY: Cambridge University Press; 2009:188-269.

(4.) Krasinskas AM, Goldsmith JD. Immunohistology of the gastrointestinal tract. In: Dabbs DJ, ed. Diagnostic Immunohistochemistry: Theranostic and Genomic Applications. 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:508-539.

(5.) Bellizzi AM. Assigning site of origin in metastatic neuroendocrine neoplasms: a clinically significant application of diagnostic immunohistochemistry. Adv Anat Pathol. 2013; 20(5):285-314.

(6.) Anderson GG, Weiss LM. Determining tissue of origin for metastatic cancers: meta-analysis and literature review of immunohistochemistry performance. Appl Immunohistochem Mol Morphol. 2010; 18(1):3-8.

(7.) Sharma MR, Schilsky RL. GI cancers in 2010: new standards and a predictive biomarker for adjuvant therapy. Nat Rev Clin Oncol. 2011; 8(2):70-72.

(8.) Ruschoff J, Hanna W, Bilous M, et al. HER2 testing in gastric cancer: a practical approach. Mod Pathol. 2012; 25(5):637-650.

(9.) Albarello L, Pecciarini L, Doglioni C. HER2 testing in gastric cancer. Adv Anat Pathol. 2011; 18(1):53-59.

(10.) Hechtman JF, Polydorides AD. HER2/neu gene amplification and protein overexpression in gastric and gastroesophageal junction adenocarcinoma: a review of histopathology, diagnostic testing, and clinical implications. Arch Pathol Lab Med. 2012; 136(6):691-697.

(11.) Beamer LC, Grant ML, Espenschied CR, et al. Reflex immunohistochemistry and microsatellite instability testing of colorectal tumors for Lynch syndrome among US cancer programs and follow-up of abnormal results. J Clin Oncol. 2012; 30(10):1058-1063.

(12.) Shia J. Immunohistochemistry versus microsatellite instability testing for screening colorectal cancer patients at risk for hereditary nonpolyposis colorectal cancer syndrome, I: the utility of immunohistochemistry. J Mol Diagn. 2008; 10(4):293-300.

(13.) Yang Z, Tang LH, Klimstra DS. Gastroenteropancreatic neuroendocrine neoplasms: historical context and current issues. Semin Diagn Pathol. 2013; 30(3): 186-196.

(14.) McCall CM, Shi C, Cornish TC, et al. Grading of well-differentiated pancreatic neuroendocrine tumors is improved by the inclusion of both Ki67 proliferative index and mitotic rate. Am J Surg Pathol. 2013; 37(11):1671-1677.

(15.) Knudsen ES, Gopal P, Singal AG. The changing landscape of hepatocellular carcinoma: etiology, genetics, and therapy. Am J Pathol. 2014; 184(3):574-583.

(16.) Rizvi S, Gores GJ. Pathogenesis, diagnosis, and management of cholangiocarcinoma. Gastroenterology. 2013; 145(6):1215-1229.

(17.) Hadzic N, Finegold MJ. Liver neoplasia in children. Clin Liver Dis. 2011; 15(2):443-462.

(18.) Nault JC, Bioulac-Sage P, Zucman-Rossi J. Hepatocellular benign tumors from molecular classification to personalized clinical care. Gastroenterology. 2013; 144(5):888-902.

(19.) Yan BC, Gong C, Song J, et al. Arginase-1: a new immunohistochemical marker of hepatocytes and hepatocellular neoplasms. Am J Surg Pathol. 2010; 34(8):1147-1154.

(20.) Pan CC, Chen PC, Tsay SH, Ho DM. Differential immunoprofiles of hepatocellular carcinoma, renal cell carcinoma, and adrenocortical carcinoma: a systemic immunohistochemical survey using tissue array technique. Appl Immunohistochem Mol Morphol. 2005; 13(4):347-352.

(21.) Xie L, Jessurun J, Manivel JC, Pambuccian SE. Hepatic epithelioid angiomyolipoma with trabecular growth pattern: a mimic of hepatocellular carcinoma on fine needle aspiration cytology. Diagn Cytopathol. 2012; 40(7): 639-650.

(22.) Krings G, Ramachandran R, Jain D, et al. Immunohistochemical pitfalls and the importance of glypican 3 and arginase in the diagnosis of scirrhous hepatocellular carcinoma. Mod Pathol. 2013; 26(6):782-791.

(23.) Fujiwara M, Kwok S, Yano H, Pai RK. Arginase-1 is a more sensitive marker of hepatic differentiation than HepPar-1 and glypican-3 in fine-needle aspiration biopsies. Cancer Cytopathol. 2012; 120(4):230-237.

(24.) Fatima N, Cohen C, Siddiqui MT. Arginase-1: a highly specific marker separating pancreatic adenocarcinoma from hepatocellular carcinoma. Acta Cytol. 2014; 58(1):83-88.

(25.) McKnight R, Nassar A, Cohen C, Siddiqui MT. Arginase-1: a novel immunohistochemical marker of hepatocellular differentiation in fine needle aspiration cytology. Cancer Cytopathol. 2012; 120(4):223-229.

(26.) Radwan NA, Ahmed NS. The diagnostic value of arginase-1 immunostaining in differentiating hepatocellular carcinoma from metastatic carcinoma and cholangiocarcinoma as compared to HepPar-1. Diagn Pathol. 2012; 7:149.

(27.) Timek DT, Shi J, Liu H, Lin F. Arginase-1, HepPar-1, and Glypican-3 are the most effective panel of markers in distinguishing hepatocellular carcinoma from metastatic tumor on fine-needle aspiration specimens. Am J Clin Pathol. 2012; 138(2):203-210.

(28.) Haraguchi Y, Takiguchi M, Amaya Y, Kawamoto S, Matsuda I, Mori M. Molecular cloning and nucleotide sequence of cDNA for human liver arginase. Proc Natl Acad Sci USA. 1987; 84(2):412-415.

(29.) Roberts CC, Colby TV, Batts KP. Carcinoma of the stomach with hepatocyte differentiation (hepatoid adenocarcinoma). Mayo Clin Proc. 1997; 72(12):1154-1160.

(30.) Gopaldas R, Kunasani R, Plymyer MR, Bloch RS. Hepatoid malignancy of unknown origin-a diagnostic conundrum: review of literature and case report of collision with adenocarcinoma. Surg Oncol. 2005; 14(1):11-25.

(31.) Terracciano LM, Glatz K, Mhawech P, et al. Hepatoid adenocarcinoma with liver metastasis mimicking hepatocellular carcinoma: an immunohisto chemical and molecular study of eight cases. Am J Surg Pathol. 2003; 27(10): 1302-1312.

(32.) Su JS, Chen YT, Wang RC, Wu CY, Lee SW, Lee TY. Clinicopathological characteristics in the differential diagnosis of hepatoid adenocarcinoma: a literature review. World J Gastroenterol. 2013; 19(3):321-327.

(33.) Marchegiani G, Gareer H, Parisi A, Capelli P, Bassi C, Salvia R. pancreatic hepatoid carcinoma: a review of the literature. Dig Surg. 2013; 30(4-6):425-433.

(34.) Matsuura S, Aishima S, Taguchi K, et al. 'Scirrhous' type hepatocellular carcinomas: a special reference to expression of cytokeratin 7 and hepatocyte paraffin 1. Histopathology. 2005; 47(4):382-390.

(35.) Lee JH, Choi MS, Gwak GY, et al. Clinicopathologic characteristics and long-term prognosis of scirrhous hepatocellular carcinoma. Dig Dis Sci. 2012; 57(6):1698-1707.

(36.) Ang CS, Kelley RK, Choti MA, et al. Clinicopathologic characteristics and survival outcomes of patients with fibrolamellar carcinoma: data from the fibrolamellar carcinoma consortium. Gastrointest Cancer Res. 2013; 6(1):3-9.

(37.) Berman MA, Burnham JA, Sheahan DG. Fibrolamellar carcinoma of the liver: an immunohistochemical study of nineteen cases and a review of the literature. Hum Pathol. 1988; 19(7):784-794.

(38.) Abdul-Al HM, Wang G, Makhlouf HR, Goodman ZD. Fibrolamellar hepatocellular carcinoma: an immunohistochemical comparison with conventional hepatocellular carcinoma. Int J Surg Pathol. 2010; 18(5):313-318.

(39.) Ross HM, Daniel HD, Vivekanandan P, et al. Fibrolamellar carcinomas are positive for CD68. Mod Pathol. 2011; 24(3):390-395.

(40.) Haas JE, Muczynski KA, Krailo M, et al. Histopathology and prognosis in childhood hepatoblastoma and hepatocarcinoma. Cancer. 1989; 64(5):1082-1095.

(41.) Lee CT, Zhang L, Mounajjed T, Wu TT. High mobility group AT-hook 2 is overexpressed in hepatoblastoma. Hum Pathol. 2013; 44(5):802-810.

(42.) Klein WM, Molmenti EP, Colombani PM, et al. Primary liver carcinoma arising in people younger than 30 years. Am J Clin Pathol. 2005; 124(4):512-518.

(43.) Bioulac-Sage P, Rebouissou S, Thomas C, et al. Hepatocellular adenoma subtype classification using molecular markers and immunohistochemistry. Hepatology. 2007; 46(3):740-748.

(44.) Bioulac-Sage P, Cubel G, Taouji S, et al. Immunohistochemical markers on needle biopsies are helpful for the diagnosis of focal nodular hyperplasia and hepatocellular adenoma subtypes. Am J Surg Pathol. 2012; 36(11):1691-1699.

(45.) Balabaud C, Al-Rabih WR, Chen PJ, et al. Focal nodular hyperplasia and hepatocellular adenoma around the world viewed through the scope of the immunopathological classification. Int J Hepatol. 2013; 2013:268625.

(46.) Shafizadeh N, Kakar S. Diagnosis of well-differentiated hepatocellular lesions: role of immunohistochemistry and other ancillary techniques. Adv Anat Pathol. 2011; 18(6):438-445.

(47.) Tremosini S, Forner A, Boix L, et al. Prospective validation of an immunohistochemical panel (glypican 3, heat shock protein 70 and glutamine synthetase) in liver biopsies for diagnosis of very early hepatocellular carcinoma. Gut. 2012; 61(10):1481-1487.

(48.) Evason KJ, Grenert JP, Ferrell LD, Kakar S. Atypical hepatocellular adenoma-like neoplasms with b-catenin activation show cytogenetic alterations similar to well-differentiated hepatocellular carcinomas. Hum Pathol. 2013; 44(5):750-758.

(49.) Kakar S, Evason KJ, Ferrell LD. Well-differentiated hepatocellular neoplasm of uncertain malignant potential: proposal for a new diagnostic category-reply. Hum Pathol. 2014; 45(3):660-661.

(50.) Lok T, Chen L, Lin F, Wang HL. Immunohistochemical distinction between intrahepatic cholangiocarcinoma and pancreatic ductal adenocarcinoma. Hum Pathol. 2014; 45(2):394-400.

(51.) Rindi G, Petrone G, Inzani F. 25 years of neuroendocrine neoplasms of the gastrointestinal tract. Endocr Pathol. 2014; 25(1):59-64.

(52.) Adsay V. Ki67 labeling index in neuroendocrine tumors of the gastrointestinal and pancreatobiliary tract: to count or not to count is not the question, but rather how to count. Am J Surg Pathol. 2012; 36(12):1743-1746.

(53.) Toon CW, Walsh MD, Chou A, et al. BRAFV600E immunohistochemistry facilitates universal screening of colorectal cancers for Lynch syndrome. Am J Surg Pathol. 2013; 37(10):1592-1602.

(54.) Kuan SF, Navina S, Cressman KL, Pai RK. Immunohistochemical detection of BRAF V600E mutant protein using the VE1 antibody in colorectal carcinoma is highly concordant with molecular testing but requires rigorous antibody optimization. Hum Pathol. 2014; 45(3):464-472.

(55.) Capper D, Voigt A, Bozukova G, et al. BRAF V600E-specific immunohistochemistry for the exclusion of Lynch syndrome in MSI-H colorectal cancer. Int! Cancer. 2013; 133(7):1624-1630.

(56.) Taliano RJ, LeGolvan M, Resnick MB. Immunohistochemistry of colorectal carcinoma: current practice and evolving applications. Hum Pathol. 2013; 44(2):151-163.

(57.) Berndorff D, Gessner R, Kreft B, et al. Liver-intestine cadherin: molecular cloning and characterization of a novel Ca(2+)-dependent cell adhesion molecule expressed in .liver and intestine. J Cell Biol. 1994; 125(6):1353-1369.

(58.) Dantzig AH, Hoskins JA, Tabas LB, et al. Association of intestinal peptide transport with a protein related to the cadherin superfamily. Science. 1994; 264(5157)430-433.

(59.) Gessner R, Tauber R. Intestinal cell adhesion molecules: liver-intestine cadherin. Ann N YAcad Sci. 2000; 915(1):136-143.

(60.) Su MC, Yuan RH, Lin CY, Jeng YM. Cadherin-17 is a useful diagnostic marker for adenocarcinomas of the digestive system. Mod Pathol. 2008; 21(11): 1379-1386.

(61.) Park JH, Seol JA, Choi HJ, et al. Comparison of cadherin-17 expression between primary colorectal adenocarcinomas and their corresponding metastases: the possibility of a diagnostic marker for detecting the primary site of metastatic tumour. Histopathology. 2011; 58(2):315-318.

(62.) Panarelli NC, Yantiss RK, Yeh MM, Liu Y, Chen YT. Tissue-specific cadherin CDH17 is a useful marker of gastrointestinal adenocarcinomas with higher sensitivity than CDX2. Am J Clin Pathol. 2012; 138(2):211-222.

(63.) Lin F, Shi J, Zhu S, et al. Cadherin-17 and SATB2 are sensitive and specific immunomarkers for medullary carcinoma of the large intestine. Arch Pathol Lab Med. 2014; 138(8):1015-1026.

(64.) Weimann A, Zimmermann M, Gross M, Slevogt H, Rieger A, Morawietz L. CDX2 and LI-cadherin expression in esophageal mucosa: use of both markers can facilitate the histologic diagnosis of Barrett's esophagus and carcinoma. Int J Surg Pathol. 2010; 18(5):330-337.

(65.) Mokrowiecka A, Zonnur S, Veits L, et al. Liver-intestine-cadherin is a sensitive marker of intestinal differentiation during Barrett's carcinogenesis. Dig Dis Sci. 2013; 58(3):699-705.

(66.) Morimatsu K, Aishima S, Kayashima T, et al. Liver-intestine cadherin expression is associated with intestinal differentiation and carcinogenesis in intraductal papillary mucinous neoplasm. Pathobiology. 2012; 79(2):107-114.

(67.) Qiu HB, Zhang LY, Ren C, et al. Targeting CDH17 suppresses tumor progression in gastric cancer by downregulating Wnt/b-catenin signaling. PLoS One. 2013; 8(3):e56959.

(68.) Takamura M, Yamagiwa S, Matsuda Y, Ichida T, Aoyagi Y. Involvement of liver-intestine cadherin in cancer progression. Med Mol Morphol. 2013; 46(1):1-7.

(69.) Dobreva G, Chahrour M, Dautzenberg M, et al. SATB2 is a multifunctional determinant of craniofacial patterning and osteoblast differentiation. Cell. 2006; 125(5):971-986.

(70.) Dobreva G, Dambacher J, Grosschedl R. SUMO modification of a novel MAR-binding protein, SATB2, modulates immunoglobulin mu gene expression. Genes Dev. 2003; 17(24):3048-3061.

(71.) Britanova O, Depew MJ, Schwark M, et al. Satb2 haploinsufficiency phenocopies 2q32-q33 deletions, whereas loss suggests a fundamental role in the coordination of jaw development. Am J Hum Genet. 2006; 79(4):668-678.

(72.) Britanova O, de Juan Romero C, Cheung A, et al. Satb2 is a postmitotic determinant for upper-layer neuron specification in the neocortex. Neuron. 2008; 57(3):378-392.

(73.) Magnusson K, de Wit M, Brennan DJ, et al. SATB2 in combination with cytokeratin 20 identifies over 95% of all colorectal carcinomas. Am J Surg Pathol. 2011; 35(7):937-948.

(74.) Wang S, Zhou J, Wang XY, et al. Down-regulated expression of SATB2 is associated with metastasis and poor prognosis in colorectal cancer. J Pathol. 2009; 219(1):114-122.

(75.) Eberhard J, Gaber A, Wangefjord S, et al. A cohort study of the prognostic and treatment predictive value of SATB2 expression in colorectal cancer. Br J Cancer. 2012; 106(5):931-938.

(76.) Chen ZM, Wang HL. Alteration of cytokeratin 7 and cytokeratin 20 expression profile is uniquely associated with tumorigenesis of primary adenocarcinoma of the small intestine. Am J Surg Pathol. 2004; 28(10):1352-1359.

(77.) Jessurun J, Romero-Guadarrama M, Manivel JC. Medullary adenocarcinoma of the colon: clinicopathologic study of 11 cases. Hum Pathol. 1999; 30(7): 843-848.

(78.) Bosman FT, Carneiro F, Hruban RH, Theise ND, eds. WHO Classification of Tumours of the Digestive System. 4th ed. Lyon, France: IARC Press; 2010:138.

(79.) Alexander J, Watanabe T, Wu TT, Rashid A, Li S, Hamilton SR. Histopathological identification of colon cancer with microsatellite instability. Am J Pathol. 2001; 158(2):527-535.

(80.) Arai T, Esaki Y, Sawabe M, Honma N, Nakamura K, Takubo K. Hypermethylation of the hMLH1 promoter with absent hMLH1 expression in medullary-type poorly differentiated colorectal adenocarcinoma in the elderly. Mod Pathol. 2004; 17(2):172-179.

(81.) Hinoi T, Tani M, Lucas PC, et al. Loss of CDX2 expression and microsatellite instability are prominent features of large cell minimally differentiated carcinomas of the colon. Am J Pathol. 2001; 159(6):2239-2248.

(82.) McGregor DK, Wu TT, Rashid A, Luthra R, Hamilton SR. Reduced expression of cytokeratin 20 in colorectal carcinomas with high levels of microsatellite instability. Am J Surg Pathol. 2004; 28(6):712-718.

(83.) Winn B, Tavares R, Fanion J, et al. Differentiating the undifferentiated: immunohistochemical profile of medullary carcinoma of the colon with an emphasis on intestinal differentiation. Hum Pathol. 2009; 40(3):398-404.

(84.) Kusayanagi S, Konishi K, Miyasaka N, et al. Primary small cell carcinoma of the stomach. J Gastroenterol Hepatol. 2003; 18(6):743-747.

(85.) Chan ES, Alexander J, Swanson PE, Jain D, Yeh MM. PDX-1, CDX-2, TTF1, and CK7: a reliable immunohistochemical panel for pancreatic neuroendocrine neoplasms. Am J Surg Pathol. 2012; 36(5):737-743.

(86.) Denby KS, Briones AJ, Bourne PA, et al. IMP3, NESP55, TTF-1 and CDX2 serve as an immunohistochemical panel in the distinction among small-cell carcinoma, gastrointestinal carcinoid, and pancreatic endocrine tumor metastasized to the liver. Appl Immunohistochem Mol Morphol. 2012; 20(6):573-579.

(87.) Li Z, Zhou K, Mei K, Kang Q, Cao D. SATB2 is a highly sensitive marker for hindgut well-differentiated neuroendocrine tumors. Mod Pathol. 2013; 26(suppl 2):164A.

(88.) Miettinen M, Killian JK, Wang ZF, et al. Immunohistochemical loss of succinate dehydrogenase subunit A (SDHA) in gastrointestinal stromal tumors (GISTs) signals SDHA germline mutation. Am J Surg Pathol. 2013; 37(2):234-240.

(89.) Dwight T, Benn DE, Clarkson A, et al. Loss of SDHA expression identifies SDHA mutations in succinate dehydrogenase-deficient gastrointestinal stromal tumors. Am J Surg Pathol. 2013; 37(2):226-233.

(90.) Miettinen M, Wang ZF, Sarlomo-Rikala M, Osuch C, Rutkowski P, Lasota J. Succinate dehydrogenase-deficient GISTs: a clinicopathologic, immunohistochemical, and molecular genetic study of 66 gastric GISTs with predilection to young age. Am J Surg Pathol. 2011; 35(11):1712-1721.

(91.) Miettinen M, Sarlomo-Rikala M, McCue P, et al. Mapping of succinate dehydrogenase losses in 2258 epithelial neoplasms. Appl Immunohistochem Mol Morphol. 2014; 22(1):31-36.

(92.) Slamon DJ, Godolphin W, Jones LA, et al. Studies of the HER2/neu protooncogene in human breast and ovarian cancer. Science. 1989; 244(4905):707-712.

(93.) Krishnamurti U, Silverman JF. HER2 in breast cancer: a review and update. Adv Anat Pathol. 2014; 21(2):100-107.

(94.) Bang YJ, Van Cutsem E, Feyereislova A, et al; ToGA Trial Investigators. Trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomised controlled trial. Lancet. 2010; 376(9742):687-697.

(95.) Kunz PL, Mojtahed A, Fisher GA, et al. HER2 expression in gastric and gastroesophageal junction adenocarcinoma in a US population: clinicopathologic analysis with proposed approach to HER2 assessment. Appl Immunohistochem Mol Morphol. 2012; 20(1):13-24.

(96.) Davies H, Bignell GR, Cox C, et al. Mutations of the BRAF gene in human cancer. Nature. 2002; 417(6892):949-954.

(97.) Long GV, Wilmott JS, Capper D, et al. Immunohistochemistry is highly sensitive and specific for the detection of V600E BRAF mutation in melanoma. Am J Surg Pathol. 2013; 37(1):61-65.

(98.) Koperek O, Kornauth C, Capper D, et al. Immunohistochemical detection of the BRAF V600E-mutated protein in papillary thyroid carcinoma. Am J Surg Pathol. 2012; 36(6):844-850.

(99.) Xing M, Alzahrani AS, Carson KA, et al. Association between BRAF V600E mutation and mortality in patients with papillary thyroid cancer. JAMA. 2013; 309(14):1493-1501.

(100.) Preusser M, Capper D, Berghoff AS, et al. Expression of BRAF V600E mutant protein in epithelial ovarian tumors. Appl Immunohistochem Mol Morphol. 2013; 21(2):159-164.

(101.) Tiacci E, Trifonov V, Schiavoni G, et al. BRAF mutations in hairy-cell leukemia. N Engl J Med. 2011; 364(24):2305-2315.

(102.) Sinicrope FA, Smyrk TC, Tougeron D, et al. Mutation-specific antibody detects mutant BRAFV600E protein expression in human colon carcinomas. Cancer. 2013; 119(15):2765-2770.

(103.) Toon CW, Chou A, Desilva K, et al. BRAFV600E immunohistochemistry in conjunction with mismatch repair status predicts survival in patients with colorectal cancer. Mod Pathol. 2014; 27(5):644-650.

(104.) Routhier CA, Mochel MC, Lynch K, Dias-Santagata D, Louis DN, Hoang MP. Comparison of 2 monoclonal antibodies for immunohistochemical detection of BRAF V600E mutation in malignant melanoma, pulmonary carcinoma, gastrointestinal carcinoma, thyroid carcinoma, and gliomas. Hum Pathol. 2013; 44(11):2563-2570.

(105.) Adackapara CA, Sholl LM, Barletta JA, Hornick JL. Immunohistochemistry using the BRAF V600E mutation-specific monoclonal antibody VE1 is not a useful surrogate for genotyping in colorectal adenocarcinoma. Histopathology. 2013; 63(2):187-193.

Zongming Eric Chen, MD, PhD; Fan Lin, MD, PhD

Accepted for publication May 29, 2014.

From the Department of Laboratory Medicine, Geisinger Medical Center, Danville, Pennsylvania.

The authors have no relevant financial interest in the products or companies described in this article.

Reprints: Zongming Eric Chen, MD, PhD, Department of Laboratory Medicine, MC 01-31, Geisinger Medical Center, 100 N Academy Ave, Danville, PA 17822 (e-mail: zechen@geisinger.edu).

Caption: Figure 1. a and b, Hepatocellular carcinoma. a, Hepatocyte paraffin 1 (HepPar1) staining. b, Arginase 1 (ARG1) staining. c and d, Hepatoblastoma. c, HepPar1 staining. d, ARG1 staining (original magnifications X100 [a and b] and X200 [c and d]).

Caption: Figure 2. Medullary carcinoma of the colon. a, Special AT-rich sequence binding protein 2 staining. b, Cadherin 17 staining (original magnification X200).

Caption: Figure 3. Metastatic, well-differentiated neuroendocrine tumor from rectum. a, Cadherin 17 staining. b, Special AT-rich sequence binding protein 2 staining (original magnification X200).
Table 1. A Panel of Immunomarkers Helpful in
Confirming Hepatocellular Differentiation

Markers   Staining Pattern   Sensitivity, %   Specificity, %

ARG1      Cytoplasmic            80-95            95-100
            and nuclear
HepPar1   Cytoplasmic            70-80             ~80
GPC3      Cytoplasmic            50-80             ~95
pCEA      Canalicular              90              l00
CD10      Canalicular             n/a              n/a
CD34      Sinusoidal              n/a              n/a

Abbreviations: ARG1, arginase 1; GPC3, glypican 3; HepPar1,
hepatocyte paraffin 1; n/a, not available; pCEA, polyclonal
carcinoem-bryonic antigen.

Table 2. Immunohistochemistry Markers and Staining Patterns in
Different Types of Hepatocellular Adenoma

                             LFABP     SAA/CRP

HNF1 [alpha] inactivation   Negative   Negative
[beta]-Catenin activated    Positive   Negative
Inflammatory                Positive   Positive
Unclassified                Positive   Negative
FNH                         Positive   Negative
Normal liver                Positive   Negative

                                      GS

HNF1 [alpha] inactivation   Central vein
[beta]-Catenin activated    Diffusely positive
Inflammatory                Central vein
Unclassified                Central vein
FNH                         Irregular anastomosing
Normal liver                Central vein

                               [beta]-Catenin

HNF1 [alpha] inactivation   Membranous
[beta]-Catenin activated    Nuclear
Inflammatory                Membranous or nuclear
Unclassified                Membranous
FNH                         Membranous
Normal liver                Membranous

Abbreviations: CRP, C-reactive protein; FNH, focal nodular
hyperplasia; GS, glutamine synthetase; HNF1 a, hepatocyte nuclear
factor la; LFABP, liver fatty acid binding protein; SAA, serum
amyloid-associated protein.

Table 3. Immunohistochemistry Markers to
Differentiate Well-Differentiated Hepatocellular
Carcinoma From Hepatocellular Adenoma

Markers   Malignant    Benign         Sensitivity,   Specificity,
                                           %              %

GPC3      Positive     Negative          40-60          95-100
HSP70     Positive     Negative          40-60          95-100
GS        Diffuse      Patchy/focal       ~80            ~50
          positive
PCNA or   High         Low                ~90            ~60
  Ki-67

Abbreviations: GPC3, glypican 3; GS, glutamine synthetase; HSP70,
heat shock protein 70; PCNA, proliferative cell nuclear antigen.

Table 4. Immunohistochemistry Markers to Differentiate
Intrahepatic Cholangiocarcinoma (IHCCA) From Metastases (a)

Markers    IHCCA    Lung-A    PDA     Upper GI   Colon   Breast

CK7          +        +        +         +         -       +
CK20         -        -        -       + or -      +       -
GATA3        -        -       -/+        -         -       +
ER           -        -        -         -         -       +
TTF1         -        +        -         -         -       -
Napsin A     -        +        -         -         -       -
SATB2        -        -        -       - or +      +       -
pVHL         +        -        -         -         -       -
CDH17       +/-       -       +/-        +         +       -
DPC4       - or +     +      - or +      +         +       +
CK17       + or -     -      + or -      -         -       -

Markers    Bladder

CK7           +
CK20
GATA3         +
ER            -
TTF1          -
Napsin A      -
SATB2         -
pVHL          -
CDH17        -/+
DPC4          +
CK17         -/+

Abbreviations: Bladder, urothelial carcinoma; CDH17, cadherin 17; CK,
cytokeratin; DPC4, SMAD family member 4; ER, estrogen receptor; GATA3,
GATA-binding protein 3; GI, gastrointestinal; Lung-A, lung
adenocarcinoma; PDA, pancreatic ductal adenocarcinoma; pVHL, von
Hippel-Lindau tumor suppressor; SATB2, special AT-rich sequence
binding protein 2; TTF1, thyroid transcription factor 1.

(a) "+" indicates that usually more than 75% of cases are
positive; "-," less than 5% of cases are positive; "+ or -," usually
more than 50% of cases are positive; and "- or +," less than 50% of
cases are positive.
COPYRIGHT 2015 College of American Pathologists
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2015 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Special Issue--An Update in Immunohistochemistry (Part II)
Author:Chen, Zongming Eric; Lin, Fan
Publication:Archives of Pathology & Laboratory Medicine
Date:Jan 1, 2015
Words:8493
Previous Article:Immunohistochemistry in Dermatopathology.
Next Article:Review and Updates of Immunohistochemistry in Selected Salivary Gland and Head and Neck Tumors.
Topics:

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters