The value of 'mesothelium-associated' antibodies in distinguishing between metastatic renal cell carcinomas and mesotheliomas

Use of Immunohistochemical Marker Calretinin in the Diagnosis of a Diffuse Malignant Metastatic Mesothelioma in an Equine

Mesotheliomas are rarely reported in animal species. In this report, the occurrence of a diffuse, metastatic mesothelioma in a 6-year-old gray Arabian mare is described. The mare was presented on clinical examination with ascites, bilateral pleural effusion, and pleural roughening. Necropsy revealed abundant fluid in the abdominal and thoracic cavities. The surface of all organs was thick and fibrosed with multiple raised nodules and hemorrhages. Histology was characteristic of a generalized, biphasic mesothelioma with vascular and lymph nodes metastases. It is believed that the primary tumor developed in the pericardium and spread through lymphatics. In this report, calretinin was used as an immunohistochemical marker in the diagnosis of mesothelioma in an equine species for the first time.

Value of PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4 immunostaining in distinguishing pleural epithelioid mesothelioma from metastatic renal cell carcinoma

Both mesotheliomas and renal cell carcinomas can present a wide variety of cytomorphologic features and histologic patterns. Because of this, renal cell carcinomas metastatic to the pleura and lung can be confused with mesotheliomas. Recently, a variety of positive carcinoma markers, including kidney-associated markers, have become available. The aim of this study is to investigate the value of some of these markers, specifically PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4, for assisting in distinguishing pleural epithelioid mesotheliomas from metastatic renal cell carcinomas. To do so, a total of 40 pleural epithelioid mesotheliomas and 55 renal cell carcinomas (33 clear cell, 10 papillary, and 12 chromophobe) were investigated. In all, 91% of the renal cell carcinomas expressed claudin-4, 89% PAX8, 60% PAX2, 71% carbonic anhydrase IX, and 29% napsin A. All of the mesotheliomas were positive for carbonic anhydrase IX and were negative for all of the other markers. On the basis of these results, it is concluded that claudin-4 and PAX8 have a higher sensitivity and specificity for assisting in discriminating between pleural epithelioid mesotheliomas and renal cell carcinomas when compared with all of the other positive carcinoma markers that are, at present, recommended to be included in the immunohistochemical panels used in this differential diagnosis. Even though PAX2 and napsin A are highly specific, because of their low sensitivity, they have only a limited value. Carbonic anhydrase IX is not useful.

Application of immunohistochemistry in the diagnosis of epithelioid mesothelioma: a review and update

A large number of immunohistochemical markers that can assist in the differential diagnosis of epithelioid mesotheliomas are currently available. Because these markers are expressed differently in the various types of carcinomas that can metastasize to the serosal membranes and can potentially be confused with epithelioid mesothelioma, their selection for inclusion in a diagnostic panel largely depends on the differential diagnosis, as well as on which ones work the best in a given laboratory. Traditionally, the panels used in the differential diagnosis of epithelioid mesothelioma have consisted of a combination of positive mesothelioma markers and broad-spectrum carcinoma markers. At present, a wide variety of organ-associated carcinoma markers such as thyroid transcription factor-1 and napsin A for the lung, PAX 8 and PAX 2 for the kidney, and Müllerian-derived tumors; gross cystic disease fluid protein-15 and mammaglobin for the breast; and CDX2 for intestinal differentiation are available, which can assist in establishing the site of origin of an adenocarcinoma when included in a diagnostic panel. This article provides updated information on the composition of the panels of markers recommended in the various differential diagnoses.

Application of immunohistochemistry to the diagnosis of malignant mesothelioma

CONTEXT

The diagnosis of malignant mesothelioma (MM) is rendered with the aid of immunohistochemistry to demonstrate the presence of "mesothelial," "epithelial," or "sarcomatous" differentiation. Antibody panels that have been proposed for the distinction between MM and other neoplasms usually include 2 or more epithelial markers used to exclude the diagnosis of a carcinoma, such as monoclonal and polyclonal carcinoembryonic antigen, Ber-EP4, B72.3, CD15, MOC-31, thyroid transcription factor 1, BG8, and others, and 2 or more mesothelial markers used to confirm the diagnosis of MM, such as cytokeratin 5/6, calretinin, HBME-1, thrombomodulin, WT-1, mesothelin, D2-40, and podoplanin. In general, most antibody panels provide excellent sensitivity and specificity for the differential diagnosis between MM epithelial variant and adenocarcinoma, particularly of lung origin. However, the accuracy of these markers is lower for the diagnosis of sarcomatous MM and for the differential diagnosis between MM and squamous cell carcinoma and carcinomas of renal, ovarian, and other origin.

OBJECTIVE

To identify optimal antibody panels for the diagnosis of MM.

DATA SOURCES

Literature review to determine how many and which mesothelial and epithelial markers need to be included in differential diagnosis antibody panels.

CONCLUSIONS

Various antibody panels have been recommended for the diagnosis of MM, with no overall consensus about how many and which markers should be used. A recent study with Bayesian statistics has demonstrated that the use of many markers does not provide higher diagnostic accuracy than the use of selected single antibodies or various combinations of only 2 markers. There is a need for the development of evidence-based or consensus-based guidelines for the diagnosis of MM in different differential diagnosis situations.

What are the current best immunohistochemical markers for the diagnosis of epithelioid mesothelioma? A review and update

Numerous immunohistochemical markers that can assist in the diagnosis of epithelioid mesotheliomas, some of which have only recently been recognized, are currently available. Because the various types of carcinomas express these markers differently, their selection for inclusion in a diagnostic panel can vary according to the differential diagnosis. This article provides a critical review of all of the information that is presently available on those markers that are believed to have the greatest potential for assisting in distinguishing between epithelioid mesotheliomas and those carcinomas with which they are most likely to be confused. Information is also provided regarding the panels of immunohistochemical markers that are, at present, recommended in these differential diagnoses.

My approach to the diagnosis of mesothelial lesions

Mesothelial lesions pose considerable diagnostic challenges not only because benign tumours, reactive proliferations and malignant mesothelioma can mimic one another, but also because the morphological patterns displayed by malignant mesothelioma can simulate a variety of epithelial and non-epithelial malignancies. Immunohistochemical markers can aid in distinguishing epithelioid malignant mesothelioma from metastatic adenocarcinoma, but because no single marker reliably separates all cases, a panel of stains is recommended. Immunohistochemical studies are of more limited value in sarcomatoid malignant mesothelioma, and other features often play an essential role. The separation of reactive mesothelial proliferations from malignant mesothelioma on small biopsy can be quite difficult, as distinguishing features, such as stromal invasion, often cannot be adequately assessed. In adequately sampled lesions, however, the distinction between malignant mesothelioma, benign mesothelial proliferations and other tumours can be achieved in most cases by using a carefully integrated approach that incorporates clinical and radiographic data, immunohistochemical studies and, in selected cases, histochemical and ultrastructural techniques.

[Expression of cytokeratin 5 and calretinin in clear-cell renal cell carcinoma]

PURPOSE

Cytokeratin 5 (CK5) and calretinin have been useful in different studies as immunohistochemical markers suggestive of mesothelioma, and their expression is analyzed for the histological differential diagnosis with adenocarcinomas, specially when confronting with metastatic tumors of unknown origin. We have analyzed the expression of CK5 and calretinin in clear cell renal cell carcinoma.

METHODS

A series of 63 clear cell renal cell carcinomas was studied. 46 of these cases were embedded in two tissue arrays, and a second group, of 17 cases, was constituted by conventional paraffin blocks from high-grade tumors (grade 4 of Fuhrman). Immunohistochemical staining was performed with monoclonal antibodies against CK5 and calretinin, following the labeled sptreptavidin-biotin technique.

RESULTS

No positivity for calretinin was observed in any case, while CK5 was focally expressed, in an isolated group of cells, in 1 of the 63 cases (1,59%) which corresponded to a high-grade carcinoma (grade 4 of Fuhrman).

CONCLUSIONS

Expression of calretinin was not observed in clear cell renal cell carcinoma and positivity for CK5 occurred only in one case, in a very small proportion of tumor cells. Therefore, in practice, although the positivity for these markers cannot completely exclude renal cell carcinoma, this result is very rare in this tumor and other diagnostic posibilities should be considered.

Expression of renal cell carcinoma-associated markers erythropoietin, CD10, and renal cell carcinoma marker in diffuse malignant mesothelioma and metastatic renal cell carcinoma

CONTEXT

Metastatic renal cell carcinoma (MRCC) involving the thorax can be difficult to distinguish from diffuse malignant mesothelioma (DMM) using traditional morphologic approaches. Standard panels of immunohistochemical markers are of limited benefit.

OBJECTIVE

To investigate several antibodies to renal cell carcinoma-associated proteins for differentiating MRCC from DMM.

DESIGN

One hundred DMMs and 20 MRCCs were evaluated for immunoexpression of erythropoietin. The same cases and an additional 45 DMMs were evaluated for CD10 and renal cell carcinoma marker (RCCMa) immunoreactivity.

RESULTS

Erythropoietin was expressed in 100% of DMMs and MRCCs. Staining for CD10 was observed in 54% of DMMs and 100% of MRCCs. RCCMa stained 26% of DMMs and 55% of MRCCs. Although erythropoietin staining was similarly strong and diffuse in both DMM and MRC, patterns of staining for RCCMa and CD10 differed between MRCC and DMM. Immunoreactivity was strong and diffuse for both RCCMa and CD10 in most MRCCs. Of CD10-positive DMMs, nearly half showed staining in less than 50% of tumor cells and about one fourth of positive cases exhibited only weak to moderately intense staining. Only half of RCCMa-positive DMMs showed staining in more than 49% of tumor cells and staining was only weak to moderately intense in most cases.

CONCLUSIONS

Given the overlap in the expression of renal cell carcinoma markers in MRCC and DMM, results with these markers must be interpreted cautiously and should be used in conjunction with mesothelium-associated markers. Differences in expression may potentially help distinguish MRCC from DMM inasmuch as strong and diffuse expression of RCCMa and CD10 supports a diagnosis of MRCC over DMM.

Evaluation of 12 antibodies for distinguishing epithelioid mesothelioma from adenocarcinoma: identification of a three-antibody immunohistochemical panel with maximal sensitivity and specificity

We evaluated the sensitivity and specificity of 10 monoclonal and two polyclonal antibodies for distinguishing epithelioid mesothelioma from adenocarcinoma (AdCA) using immunohistochemistry (IHC). The antibodies were directed against the mesothelial-associated antigens mesothelin, calretinin, cytokeratin 5, thrombomodulin, Wilms' tumor-1 (WT-1) gene product and HBME-1, and the nonmesothelial antigens Lewis-Y blood group (antibody BG8), MOC-31, BerEp4, CD15, and carcinoembryonic antigen (CEA) family. The 133 tumors evaluated included 65 malignant epithelioid mesotheliomas, 22 lung AdCAs, 27 ovarian serous carcinomas, 24 breast carcinomas, and five gastric carcinomas. Diagnoses were based on clinical, histologic, ultrastructural, and/or IHC findings. Calretinin had the best sensitivity for mesothelioma (95%), followed by HBME-1 (84%), WT-1 (78%), cytokeratin 5 (76%), mesothelin (75%), and vimentin and thrombomodulin (68%). Thrombomodulin had the best specificity for mesothelioma (92%), followed by cytokeratin 5 (89%), calretinin (87%) vimentin (84%), and HBME-1 (45%). When ovarian carcinomas were excluded from the analysis, the specificity of mesothelin and WT-1 for the diagnosis of mesothelioma increased to 90 and 81%, respectively. The sensitivity of the nonmesothelial antigens for AdCA was organ dependent, with BG8 performing best in the breast cancer group (96%), and BerEp4, BG8, MOC-31 performing best in the lung cancer group (100%). The specificity of the nonmesothelial antigens for AdCA was 98% for BG8 and CEA, 97% for CD15, 95% for BerEp4, and 87% for MOC-31. A novel statistical analysis technique employing logic regression analysis identified a three-antibody immunohistochemical panel including calretinin, BG8, and MOC-31, which provided over 96% sensitivity and specificity for distinguishing epithelioid mesothelioma from AdCA.

Spindle cell tumors of the pleura: differential diagnosis

Spindle cell tumors that arise in or metastasize to the pleura must be thoroughly evaluated to arrive at a definitive diagnosis. Malignant mesothelioma is the most common tumor arising in the pleura, but metastatic tumors to the pleura occur more frequently. Additionally, many tumors arising in the lung and surrounding tissues involve the pleura. It is crucial to arrive at a correct diagnosis since many of these neoplasms show different prognoses and require varying treatment modalities. Sarcomatoid malignant mesothelioma is a rare tumor that arises in the pleura, and can be confused with numerous tumors arising in or metastasizing to the pleura, including synovial sarcoma, metastatic sarcomatoid carcinoma, metastatic melanoma, thymoma, renal cell carcinoma, localized fibrous tumor, leiomyosarcoma, and other types of sarcoma. Desmoplastic malignant mesothelioma is a fibrous sarcomatoid variant of malignant mesothelioma, and is occasionally mistaken for chronic fibrous pleurisy. Here, we review morphological, clinical, histological, immunohistochemical, ultrastructural, and molecular methods that aid in the diagnosis of spindle cell tumors of the pleura, and we provide specific examples of patients in which this multi-modal approach proved to be helpful.

The diagnostic utility of immunohistochemistry in distinguishing between mesothelioma and renal cell carcinoma: A comparative study

Both mesotheliomas and renal cell carcinomas can present a wide variety of morphological patterns. Because of this, renal cell carcinomas that metastasize to the pleura and lung may be confused with mesotheliomas. The aim of the present study was to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and renal cell carcinoma. A total of 48 mesotheliomas (40 epithelioid, 8 sarcomatoid), and 48 renal cell carcinomas (24 conventional, 12 chromophobe, 8 papillary, 4 sarcomatoid) were investigated for the expression of the following markers: calretinin, mesothelin, cytokeratin 5/6, WT1, thrombomodulin (TM), N-cadherin, CD15 (leu-M1), MOC-31, Ber-EP4, BG-8 (Lewis(y)), CD10, renal cell carcinoma marker (RCC Ma), carcinoembryonic antigen (CEA), and B72.3. All (100%) of the epithelioid mesotheliomas reacted for calretinin, mesothelin, and cytokeratin 5/6; 93% for WT1; 78% for TM; 75% for N-cadherin, 48% for CD10, 15% for Ber-EP4, 8% for MOC-31, 8% for RCC Ma, 5% for BG-8, and none for CEA, B72.3, or CD15. Of the sarcomatoid mesotheliomas, 88% expressed calretinin, 75% N-cadherin, 38% CD10, and 13% each expressed cytokeratin 5/6, WT1, and TM. All of the remaining markers were negative. Among the RCCs, 81% expressed CD10, 75% N-cadherin, 63% CD15, 50% RCC Ma, 50% MOC-31, 42% Ber-EP4, 8% BG-8, and 2% TM. The remaining markers were negative. The results indicate that calretinin, mesothelin, and cytokeratin 5/6 are the best positive mesothelioma markers for differentiating epithelioid mesotheliomas from renal cell carcinomas. The best discriminators among the antibodies considered negative markers for mesothelioma are CD15, MOC-31, and RCC Ma. An accurate differential diagnosis can be reached with the use of any 2 of the 3 recommended positive markers, which should be selected based on availability and on which ones yield the best staining results in a given laboratory. One of the recommended negative markers may be added to the panel if deemed necessary. If confirmation of renal origin is needed, RCC Ma could be useful. Calretinin is the only marker that appears to have any utility in distinguishing between sarcomatoid mesotheliomas and sarcomatoid renal cell carcinomas.

Diagnostic value of MUC4 immunostaining in distinguishing epithelial mesothelioma and lung adenocarcinoma

The distinction between pleural malignant mesothelioma and pleural infiltration by adenocarcinomas has complex therapeutic and medicolegal implications. Although the panel of adenocarcinoma-associated antibodies and one or two mesothelioma markers is useful in this purpose, most of these antibodies are not totally specific. We determined the diagnostic value of MUC4 immunostaining in this issue. MUC4 gene expression was also studied by in situ hybridization and RT-PCR. MUC4 is a membrane-bound mucin that has been suggested to be implicated in malignant progression in humans and rats. The MUC4 gene is expressed in various normal epithelial tissues of endodermic origin and carcinomas. In the respiratory tract, MUC4 transcripts have been detected in normal respiratory epithelium and lung carcinomas. MUC4 protein was expressed in 32 of 35 (91.4%) lung adenocarcinomas on paraffin-embedded tissue. None of the 41 malignant mesotheliomas nor the 32 cases of benign mesothelial cells expressed MUC4 at the protein and mRNA levels. We conclude that MUC4 is a very specific (100%) and sensitive (91.4%) marker of lung adenocarcinomas on paraffin-embedded tissue that could be useful in diagnostic practice in the distinction between malignant mesothelioma and adenocarcinoma.

‘Pseudomesotheliomatous’ carcinomas of the pleura: a 10-year analysis of cases from the Environmental Lung Disease Research Group, Cardiff

AIMS

To undertake a clinicopathological study of diffuse serosal neoplasms of epithelial histogenesis which clinically and pathologically mimic malignant pleural mesothelioma.

METHODS AND RESULTS

Over a 10-year (1990-2000) study period 53 carcinomas mimicking diffuse pleural mesothelioma ('pseudomesotheliomatous' carcinoma) were identified. The study group comprised 50 men and three females, age range 33-77 (median 68) years. In 46 (87%) cases there was a history of smoking and in 40 (76%) cases a history of asbestos exposure. Histologically the pleural 'pseudomesotheliomatous' carcinomas could be divided into two broad groups: primary pulmonary carcinomas with florid pleurotropic growth (n = 47), of which 34 (70%) were adenocarcinomas; and diffuse carcinomatous involvement of the pleura by metastatic tumour (n = 6). This latter group comprised two transitional cell carcinomas of bladder, one renal (clear) cell carcinoma, one ductal pancreatic adenocarcinoma, one prostatic adenocarcinoma and one squamous cell carcinoma of parotid gland origin. Follow-up data were available in 35 cases. Regardless of tumour type, survival was poor (median 8 months) and comparable to diffuse pleural mesothelioma.

CONCLUSIONS

Pleural 'pseudomesotheliomatous' carcinomas are uncommon (comprising 6% of referrals), pathologically heterogeneous tumours with poor prognosis. Tissue diagnosis should be obtained in all cases of suspected diffuse pleural neoplasia. By light microscopy and immunophenotype many of the tumours mimicked malignant mesothelioma. In particular, an awareness that all neoplasms exhibiting squamous differentiation may express cytokeratin 5/6 and thrombomodulin is important to prevent misinterpretation. In this respect, calretinin is regarded as the most specific and sensitive mesothelial marker. Misdiagnosis may have medico-legal implications in asbestos-related compensation claims.