Immunohistochemical evaluation of pleural mesothelioma and pulmonary adenocarcinoma. A bi-institutional study of 47 cases

Performance of the Monoclonal Antibody B72.3 in Diagnosis of Malignant Carcinomatous Serous Effusions-A Systematic Review and Meta-Analysis of Diagnostic Performance

OBJECTIVES

Immunocytochemistry is often required in the cytologic assessment of malignant serous effusion, particularly for differentiating metastatic carcinoma from mesothelioma. To summarise the diagnostic performance of the monoclonal antibody B72.3, a systematic review and meta-analysis was conducted.

METHODS

Five databases were searched for relevant studies and reviewed for data extraction and risk of bias assessment. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under curve of summary receiver operating characteristics (AUC-SROC) were calculated for the diagnostic performance of B72.3. Heterogeneity and publication bias were assessed by the I2 index and Deeks' funnel plot.

RESULTS

In total, 19 studies (1159 cases) were included. Overall pooled sensitivity and specificity were 0.76 (0.72-0.79) and 0.90 (0.74-1.00), respectively. The NLR, PLR and DOR were 0.27 (0.21-0.34), 7.66 (< 0.001-20.46) and 28.26 (0-75.96), respectively. The AUC-SROC was 0.98, indicating a good overall diagnostic accuracy for B72.3. Subgroup analysis for adenocarcinoma (0.75, 0.71-0.79), mesothelioma (0.92, 0.85-0.98) and benign/reactive mesothelial cells (0.96, 0.93-1.00) showed similar sensitivity and specificity, while the sensitivity for adenocarcinomas of the gastrointestinal/hepatobiliary tract (0.56, 0.41-0.71) and breast (0.55, 0.38-0.71) was significantly lower. High heterogeneity was observed in the majority of our analyses, while no evidence of publication bias was identified.

CONCLUSIONS

B72.3 has an acceptable performance with low sensitivity. With a good specificity, B72.3 may find use in an immunocytochemical panel for excluding benign mesothelial processes.

Differential Diagnosis of Epithelioid Malignant Mesothelioma With Lung and Breast Pleural Metastasis: A Systematic Review Compared With a Standardized Panel of Antibodies-A New Proposal That May Influence Pathologic Practice

CONTEXT.—

Pleural mesothelioma is a rare cancer with an often-challenging diagnosis because of its potential to be a great mimicker of many other tumors. Among them, primary lung and breast cancers are the 2 main causes of pleural metastasis. The development and application of targeted therapeutic agents have made it even more important to achieve an accurate diagnosis. In this setting, international guidelines have recommended the use of 2 positive and 2 negative immunohistochemical biomarkers.

OBJECTIVES.—

To define the most highly specific and sensitive minimum set of antibodies for routine practice to use for the separation of epithelioid malignant mesothelioma from lung and breast metastasis and to determine the most relevant expression cutoff.

DESIGN.—

To provide information at different levels of expression of 16 mesothelial and epithelial biomarkers, we performed a systematic review of articles published between 1979 and 2017, and we compared those data to results from the Mesothelioma Telepathology Network (MESOPATH) of the standardized panel used in routine practice database since 1998.

RESULTS.—

Our results indicate that the following panel of markers-calretinin (poly)/thyroid transcription factor 1 (TTF-1; clone 8G7G3/1) and calretinin (poly)/estrogen receptor-α (ER-α; clone EP1)-should be recommended; ultimately, based on the MESOPATH database, we highlight their relevance which are the most sensitive and specific panel useful to the differential diagnosis at 10% cutoff.

CONCLUSIONS.—

Highlighted by their relevance in the large cohort reported, we recommend 2 useful panels to the differential diagnosis at 10% cutoff.

Malignant Mixed Müllerian Tumor of the Peritoneum

This clinicopathologic study of three patients with malignant mixed Müllerian tumor of the peritoneum and review of the literature shows that this tumor is relatively rare and has a grim prognosis. It can be differentiated from other biphasic neoplasms that may involve the female peritoneum primarily or secondarily. Differential diagnostic criteria are proposed for distinguishing this tumor from a biphasic malignant mesothelioma. Int J Surg Pathol 3(3) :155-162, 1996

Value of immunohistochemistry in the differential diagnosis of pleural sarcomatoid mesothelioma from lung sarcomatoid carcinoma

AIMS

The differential diagnosis of pleural sarcomatoid mesothelioma (SM) from lung sarcomatoid carcinoma (LSC) invading parietal pleura and chest wall is a challenging issue. The aim of this study was to identify useful antibodies that can be used for the differential diagnosis of pleural SM from LSC.

METHODS AND RESULTS

Forty-five cases of pleural SM and 27 cases of LSC were immunohistochemically analysed by using 15 commercially available antibodies, including D2-40 and antibodies to calretinin, thrombomodulin, Wilms' Tumour 1, carcinoembryonic antigen (CEA), Napsin A, thyroid transcription factor (TTF)-1, pan-cytokeratin, CAM5.2, epithelial membrane antigen, Ber-EP4, MOC-31, alpha-smooth muscle actin, h-caldesmon and desmin. The results revealed that D2-40 positivity was significantly higher in pleural SM (86.7%) than in LSC (25.9%). The positivity of the adenocarcinoma markers, including CEA, Napsin A, and TTF-1, was low even in LSC.

CONCLUSIONS

Evaluating the positivity and degree of staining of the well-known mesothelial marker D2-40 could be applied to differentiate pleural SM from the sarcomatoid component of LSC, in addition to assessing clinical and radiological information.

Immunohistochemical marker panels for distinguishing between epithelioid mesothelioma and lung adenocarcinoma

The distinction between epithelioid mesothelioma and lung adenocarcinoma remains an important diagnostic challenge for surgical pathologists. The aim of the present study was to select a limited and appropriate panel of antibodies that can differentiate between epithelioid mesothelioma and lung adenocarcinoma. Specimens of 90 epithelioid mesotheliomas and 51 lung adenocarcinomas obtained from Japanese cases were examined using calretinin, WT1, AE1/AE3, CAM5.2, cytokeratin (CK) 5/6, vimentin, epithelial membrane antigen (EMA), thrombomodulin, CEA, CA19-9, and CA125. Ninety-six percent of epithelioid mesotheliomas were positive for calretinin; 99% for WT1; 100% for AE1/AE; 97% for CAM5.2; 70% for CK 5/6; 91% for vimentin; 96% for EMA; 71% for thrombomodulin; 77% for mesothelin; 7% for CEA; 17% for CA19-9; and 85% for CA125. In contrast, 33% of lung adenocarcinomas were positive for calretinin; 16% for WT1; 100% for AE1/AE3, CAM5.2, and EMA; 41% for CK 5/6; 47% for vimentin; 20% for thrombomodulin; 69% for mesothelin; 98% for CEA; 73% for CA19-9; and 80% for CA125. For distinguishing between epithelioid mesothelioma and lung adenocarcinoma, the combination of CEA, calretinin and each WT1 or thrombomodulin was suggested to be the best panel of immunohistochemical markers.

Malignant mesothelioma: current status of histopathologic diagnosis and molecular profile

Malignant mesothelioma of the pleura is a relatively rare neoplasm that has been estimated to account for 20 deaths per million males per year in North America and Europe. A causative association has been well established with asbestos exposure. Paradoxically, the incidence of this tumor continues to rise despite public efforts to reduce, contain or eliminate exposure to asbestos fibers over the past few decades. Another paradoxical feature of the disease is that the majority of malignant mesotheliomas represent morphologically low-grade, well-differentiated neoplasms, yet they follow a relentlessly aggressive and virtually uniformly fatal outcome. For this reason, identification of clinical, morphologic, immunohistochemical or molecular genetic parameters is of extremely limited value for prognostication. Surprisingly, for a disease that currently has no known cure, one of the major problems still lies in establishing the correct diagnosis. Diagnosis acquires a particular relevance in light of the medicolegal ramifications of this disease, and diagnosis of malignant mesothelioma is still fraught with difficulties. Despite the advances in modern diagnostic techniques, no specific markers or morphologic features exist that are exclusive to these tumors. Herein, the current status of malignant mesothelioma diagnosis is reviewed, including the possible contributions of modern molecular techniques for their diagnosis.

Applications and limitations of immunohistochemistry in the diagnosis of malignant mesothelioma

Malignant mesothelioma is an uncommon malignant epithelial neoplasm originating from the serosal surface of body cavities. Because serosal surfaces are a common site of metastatic spread for a variety of malignant neoplasms originating from internal organs, separating malignant mesothelioma from metastatic tumors is of clinical importance. The diagnosis of malignant mesothelioma is complex and usually requires a multimodal approach that includes careful clinical history and physical examination, imaging studies, and tissue sampling for multimodal evaluation including routine histology, histochemistry, electron microscopy, and immunohistochemical tests. Of these, immunohistochemistry has emerged as the most valuable and readily available modality for the routine evaluation of these tumors. Unfortunately, no specific antibodies have yet been developed that can be accepted as exclusive for these tumors. The immunohistochemical diagnosis of malignant mesothelioma therefore depends on the use of a panel of stains that includes markers that are commonly expected to react with these tumors ("positive" markers) and markers that are not commonly expected to react with these tumors ("negative" markers). Additionally, the selection and utility of these various markers can vary considerably based on a constellation of circumstances, including patient sex, histologic appearance of the tumor (ie, epithelioid vs. sarcomatoid, etc), and various other clinical circumstances. Herein, we will review the currently available immunohistochemical markers used for the diagnosis of malignant mesothelioma and offer suggestions for the use of appropriate panels of stains based on specific morphologic types and clinical circumstances.

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.

The role of immunohistochemistry in distinguishing squamous cell carcinoma from mesothelioma and adenocarcinoma in pleural effusion

BACKGROUND

Distinguishing metastatic squamous cell carcinoma (SCC) from malignant mesothelioma (MM) and adenocarcinoma (ADC) in pleural effusions may be particularly challenging by routine cytologic stains. We explored the utility of using a panel of six antibodies to differentiate SCC from MM and ADC.

DESIGN

33 cases of pleural cytologic preparations retrieved from our archives consisted of 9 cases of SCC, 12 cases of epithelial MM, and 12 cases of adenocarcinoma of lung. Cell blocks were prepared by the thrombin clot technique followed by formalin-fixation and paraffin-embedding. Tissue sections of 4 microm were stained with hematoxylin and eosin and the immunoperoxidase method visualized by the biotin-streptavidin-peroxidase system. The antibodies used were cytokeratins (CAM 5.2, K903, and CK 5/6), cell membrane glycoproteins (CEA and Ber-EP4), and calretinin. In all cases, the reactivity pattern was graded on a sliding scale from 0 to 4+ according to the percentage of reactive cells.

RESULTS

SCC was positive for K903 (100%), CK 5/6 (89%), CAM 5.2 (78%), and CEA (22%), and negative for Ber-EP4 (100%) and calretinin (100%). MM was positive for calretinin (100%), CAM 5.2 (100%), K903 (92%), CK 5/6 (92%), and negative for CEA (100%) and Ber-EP4 (100%). ADC was positive for CAM 5.2 (100%), CEA (83%), and Ber-EP4 (83%), and negative for calretinin (100%), K903 (92%) and CK 5/6 (92%).

CONCLUSIONS

Our studies confirm the role of the above panel of antibodies in distinguishing among these malignancies. Positive staining for K903, CK 5/6, and CAM 5.2 separated SCC and MM from ADC. Positive staining for calretinin separated MM from SCC and ADC. Positive staining for glycoproteins and predominantly negative staining for CK 5/6, K903 and calretinin separated ADC from SCC and MM.

Sensitivity and specificity of immunohistochemical markers used in the diagnosis of epithelioid mesothelioma: a detailed systematic analysis using published data

AIMS

Immunohistochemistry is frequently employed to aid the distinction between mesothelioma and pulmonary adenocarcinoma metastatic to the pleura, but there is uncertainty as to which antibodies are most useful. We analysed published data in order to establish sensitivity and specificity of antibodies used to distinguish between these tumours with a view to defining the most appropriate immunohistochemical panel to use when faced with this diagnostic problem.

METHODS AND RESULTS

A systematic analysis of the results of 88 published papers comparing immunohistochemical staining of a panel of antibodies in mesothelioma with epithelioid areas, and pulmonary adenocarcinoma metastatic to the pleura. Results for a total of 15 antibodies were analysed and expressed in terms of sensitivity and specificity. The most sensitive antibodies for identifying pulmonary adenocarcinoma were MOC-31 and BG8 (both 93%), whilst the most specific were monoclonal CEA (97%) and TTF-1 (100%). The most sensitive antibodies to identify epithelioid mesothelioma were CK5/6 (83%) and HBME-1 (85%). The most specific antibodies were CK5/6 (85%) and WT1 (96%).

CONCLUSIONS

No single antibody is able to differentiate reliably between these two tumours. The use of a small panel of antibodies with a high combined sensitivity and specificity is recommended.

The epidemiology of asbestos-related diseases

Asbestos has been recognised as a potential health hazard since the 1940s. Of the two major species of asbestos; white asbestos (chrysotile) and blue asbestos (crocidolite), both of which are hazardous. The workers at extraction facilities are at the greatest risk of exposure to asbestos and, therefore, the development of asbestos-related diseases, commonly mesothelioma. However, other individuals at a high risk of exposure include asbestos-cement workers, insulation workers and ship-yard workers. Environmental exposure to asbestos can occur as a result of living in areas either characterised by natural outcrops of asbestos or asbestos-related materials, or those close to asbestos-producing or -using plants. Unfortunately, man-made fibre alternatives to asbestos, such as rock and slag-wool and glass wool, have also been shown to have a detrimental effect on human health. A characteristic of mesothelioma is that there is a long latency period (20-30 years) before the signs and symptoms of the disease become apparent. In addition, diagnosis of the disease can be difficult. The use of biological markers, such as tissue polypeptide antigen, may play a useful role in the early detection of the disease in individuals at risk.

The immunohistochemical diagnosis of mesothelioma: a comparative study of epithelioid mesothelioma and lung adenocarcinoma

A large number of immunohistochemical markers that can facilitate the distinction between epithelioid pleural mesotheliomas and pulmonary peripheral adenocarcinomas have recently become available. The aim of this study is to compare the value of these new markers with others that are already commonly used for this purpose and to determine which are, at present, the best for discriminating between these malignancies. Sixty epithelioid mesotheliomas and 50 lung adenocarcinomas were investigated for expression of the following markers: calretinin, cytokeratin 5/6, WT1, thrombomodulin, mesothelin, CD44S, HBME-1, N-cadherin, E-cadherin, MOC-31, thyroid transcription factor-1 (TTF-1), BG-8 (Lewisy), carcinoembryonic antigen (CEA), Ber-EP4, B72.3 (TAG-72), leu-M1 (CD15), CA19-9, epithelial membrane antigen (EMA), and vimentin. All (100%) of the mesotheliomas reacted for calretinin, cytokeratin 5/6, and mesothelin, 93% for WT1, 93% for EMA, 85% for HBME-1, 77% for thrombomodulin; 73% for CD44S, 73% for N-cadherin, 55% for vimentin, 40% for E-cadherin, 18% for Ber-EP4, 8% for MOC-31, 7% for BG-8, and none for CEA, B72.3, leu-M1, TTF-1, or CA19-9. Of the adenocarcinomas, 100% were positive for MOC-31, Ber-EP4, and EMA, 96% for BG-8, 88% for CEA, 88% for E-cadherin, 84% for B72.3, 74% for TTF-1, 72% for leu-M1, 68% for HBME-1, 48% for CD44S, 48% for CA19-9, 38% for mesothelin, 38% for vimentin, 30% for N-cadherin, 14% for thrombomodulin, 8% for calretinin, 2% for cytokeratin 5/6, and none for WT1. After analyzing the results, it is concluded that calretinin, cytokeratin 5/6, and WT1 are the best positive markers for differentiating epithelioid malignant mesothelioma from pulmonary adenocarcinoma. The best discriminators among the antibodies considered to be negative markers for mesothelioma are CEA, MOC-31, Ber-EP4, BG-8, and B72.3. A panel of four markers (two positive and two negative) selected based upon availability and which ones yield good staining results in a given laboratory is recommended. Because of their specificity and sensitivity for mesotheliomas, the best combination appears to be calretinin and cytokeratin 5/6 (or WT1) for the positive markers and CEA and MOC-31 (or B72.3, Ber-EP4, or BG-8) for the negative markers. An extensive and detailed review of the literature is also provided.

Immunohistochemical diagnosis of epithelioid mesotheliomas: a critical review of old markers, new markers

Numerous new immunohistochemical markers that can be used in the diagnosis of mesothelioma have recently become available. As a result, new panels of antibodies that could be useful for distinguishing between epithelioid mesotheliomas and adenocarcinomas have been proposed. However, great differences of opinion exist regarding the individual value of some of these markers, especially when compared with those whose value has already been established. This article provides a critical review of the currently available information on those markers that could be useful in the diagnosis of epithelioid mesotheliomas or whose utility remains controversial. A practical approach to the diagnosis of these tumors is also provided.

Immunohistochemical differential diagnosis of pleural effusions, with emphasis on malignant mesothelioma

The immunohistochemical diagnosis of atypical epithelial proliferations in pleural fluid is a challenging topic in cytopathology and surgical pathology. Mesothelioma may be simulated clinically and radiologically by several other nonneoplastic and neoplastic disorders, mandating that strict histologic, histochemical, immunohistochemical, and ultrastructural guidelines be followed for its diagnosis. Because of its availability to most laboratories, immunohistochemistry has emerged as the most commonly used procedure for the diagnosis of pleural malignancies. This review considers the current status of that investigative modality, with particular attention to lesions that are suspected to be mesothelial.

Pleural fluid cytology: immunocytochemistry usage patterns and significance of nondefinitive diagnoses

There has been little study of how pleural fluids are interpreted in actual practice, including the use of immunocytochemistry and nondefinitive diagnoses. Pleural fluid reports (n = 1,330) from 1991-1997 and the University of Iowa cancer database were retrospectively reviewed to determine the cytologic diagnosis, requisition form history, patient survival, and use of immunocytochemistry. Nondefinitive diagnoses were made in 11.3% of cases. Immunocytochemistry was used in 2.6% of cases and aided in making a definitive diagnosis in 71.9% of cases. For patients with a clinical suspicion of malignancy, the percentages of patients who had a nondefinitive, benign, and malignant diagnosis and died of disease were 81.6%, 94.0%, and 90.6%, respectively. In conclusion, if patients had a history of malignancy and a clinical suspicion of recurrence, patient survival was dismal, regardless of the cytologic diagnosis. Immunocytochemistry was used sparsely but often aided in making a definitive diagnosis.

Pseudomesotheliomatous carcinoma involving pleura and peritoneum: A clinicopathologic and immunohistochemical study of three cases

Pseudomesotheliomatous carcinoma is a rare variant of peripheral adenocarcinoma of the lung that can manifest clinical, radiologic, and pathologic features similar to malignant mesothelioma. We present three patients with pseudomesotheliomatous carcinoma of the lung. In one patient the carcinoma extended beyond the thorax and extensively involved the peritoneum, mesentery, omentum, and intestines. All patients experienced weight loss and chest pain. All were white men aged 63, 65, and 67 years. Two were smokers and had shortness of breath, cough, and pleural effusion. One had a history of asbestos exposure. No patient developed dyspnea or hemoptysis. One was successfully treated for prostatic carcinoma 18 months earlier. Radiographically, all tumors were pleura-based. Grossly, the tumors spread extensively over pleural (and in one case peritoneal) surfaces and mimicked malignant mesothelioma. Histologically, all tumors were poorly differentiated and necrotic; two tumors exhibited spindle-cell components and desmoplasia. Mucin production was detectable in none, 10%, and 50% of tumor cells. The percentages of tumor cells immunoreactive for Ber-EP4 were 70%, 100%, and 80%; for Leu MI 0%, 90%, and 50%; for epithelial membrane antigen 80%, 80%, and 100%; for B 72.3%, 0%, 90%, and 20%; for polyclonal carcinoembryonic antigen 0%, 10%, and 10%; and for monoclonal 5%, 0%, and 0%. Of these, Ber-EP4 and B 72.3 rendered the most reliable diagnostic results. The clinical, radiologic, and gross and routine histologic findings were similar to those of a malignant mesothelioma; the final diagnosis could be made based mainly on immunocytochemical results. We have reviewed the English and German literature regarding 65 such tumors and present our experience with three additional cases. We emphasize the application of immunocytochemical studies on pleura-based poorly or undifferentiated malignant tumors of unknown origin.

Papillary carcinoma of the thymus: report of four cases of a new microscopic type of thymic carcinoma

We describe four cases of papillary carcinoma arising in the thymus. Three showed low-grade atypia and were associated with spindle cell-type thymoma. The fourth case showed high-grade atypia and had no evidence of an association with thymoma. Two of three low-grade cases invaded the lung and showed extensive lymphatic permeation. Cyst formation was seen in one case. Immunohistochemically, the tumor cells were positive for carcinoembryonic antigen (CEA), Leu-M1, Ber-EP4, calretinin (2 cases), and CD5 and were negative for thyroglobulin and pulmonary surfactant apoprotein. Ultrastructural findings for the one case studied by electron microscopy gave evidence against a mesothelial origin of the tumor. The histologic similarities and the intimate association with spindle cell thymoma indicate that papillary thymic carcinoma may arise from the papillotubular formations sometimes seen in the former tumor. Papillary thymic carcinoma, a lesion hitherto undescribed, should be considered in the differential diagnosis of anterior mediastinal tumors. Conceivably, it may be the source of some metastatic papillary carcinomas with or without psammoma bodies in cervical lymph nodes, in which no tumor is found in the thyroid gland.

A comparative evaluation of immunohistochemical markers for the differential diagnosis of malignant pleural tumours

AIMS

To determine the value of immunocytochemistry in differentiation of malignant pleural mesothelioma from carcinoma in a pleural biopsy using commercially available monoclonal antibodies.

METHODS AND RESULTS

A panel of monoclonal antibodies against keratins, epithelial membrane antigen (EMA), epithelial antigen Ber-EP4, carcinoembryonic antigen (CEA), tumour-associated glycoprotein (B72.3), Leu-M1, CD30 (Ber-H2), vimentin and desmin, was applied to 40 cases of malignant pleural mesothelioma and 23 cases of carcinoma metastatic to the pleura (16 pulmonary and seven extrapulmonary). Positivities for Ber-EP4, CEA, B72.3 and Leu-M1 were found to have the highest nosologic sensitivities (87.0%, 65.2%, 52.5% and 43.5%, respectively) and specificities (97.5%, 97.5%, 100% and 95%, respectively) for carcinoma. Positive staining for vimentin had the highest sensitivity (87.5%) with 95.7% specificity for mesothelioma. Positive staining for desmin was found in 45% of mesotheliomas and 0% of carcinomas. Diagnostic sensitivity and diagnostic specificity (P-values) were calculated for these markers. In respect to the diagnostic power defined by the clinically relevant predictive values of positive and negative tests, we found that a two-marker panel of antibodies including vimentin and Ber-EP4 is most useful for the histopathological distinction between carcinoma (pulmonary or extrapulmonary) and malignant pleural mesothelioma.

CONCLUSIONS

A combination of Ber-EP4 and vimentin provides the most sensitive and specific pair of markers for distinguishing between malignant pleural mesothelioma and carcinoma metastatic to the pleura. The prevalence of the tested tumours should be taken into account when evaluating the clinical value of ancillary techniques in pathology.

Adenocarcinoma simulating mesothelioma: a clinicopathologic and immunohistochemical study of 29 cases

We report 29 cases of adenocarcinomas whose clinical, gross, and microscopic appearance resembled diffuse malignant pleural mesothelioma. Initial criteria for inclusion in the study included availability of an open pleural biopsy or decortication specimen and microscopic evidence of neutral (periodic acid-Schiff positive) mucin in the tumor. The median age of the patients was 63 years (range, 31 to 78 years), with a peak age in the seventh decade. There were 24 men and five women. Thirteen of them had a history of smoking; six (21%) had possible or definite occupational exposure to asbestos. Three (21%) of 14 lung specimens showed ferruginous bodies and two (14%) showed microscopic evidence of asbestosis. At least 25 patients had pleural effusion, most typically unilateral. Needle biopsy of pleura showed malignancy in 10 (77%) of 13 cases. Most (20 of 29) patients underwent pleural stripping. Radiotherapy and chemotherapy was each given to three patients without effect. Median survival by Kaplan-Meier estimate was 8 months, with an 18-month survival of 13%. Histologically, glands (23 cases), nests (13 cases), tubulopapillary arrays (12 cases), or sheets (eight cases) of tumor cells were found. Spindling of neoplastic cells was seen in 10% of cases. Three (21%) of 14 lung specimens showed a subpleural adenocarcinoma. Antibodies to polyclonal CEA, Ber-EP4, Leu-M1, and B72.3 were positive in 94%, 56%, 50%, and 44% of cases, respectively. All but one of the cases stained with two or more of the antibodies CEA, Ber-EP4, Leu-M1, or B72.3. This study indicates that adenocarcinomas simulating mesothelioma are aggressive variants of peripheral adenocarcinomas with a poor prognosis, that they can show pathological evidence of asbestos exposure in a subset of cases, and that immunohistochemical and histochemical stains are useful in their differential diagnosis with diffuse malignant mesotheliomas.

TTF-1 protein expression in pleural malignant mesotheliomas and adenocarcinomas of the lung

TTF-1 is a tissue-specific transcription factor expressed in the epithelial cells of thyroid and lung. This study investigates the immunohistochemical expression of TTF-1 in pleural malignant mesotheliomas (MM) and adenocarcinomas (AC) of the lung, respectively. For this purpose, 33 biopsy specimens of pulmonary AC and 24 specimens of MM were studied. TTF-1 immunoreactivity was identified in 19 of 33 cases of AC (57.5%) and in none of the 24 cases of MM. Positivity for TTF-1 was 100% specific and 57.5% sensitive for lung AC. Alternatively, negativity for TTF-1 was 57.5% specific and 100% sensitive for MM. These results suggest that TTF-1 can be favourably added to the immunohistochemical diagnostic panel for distinction between AC of the lung involving the pleura and pleural MM.

The immunohistochemical diagnostic panel for epithelial mesothelioma: a reevaluation after heat-induced epitope retrieval

The immunohistochemical diagnosis between epithelial mesothelioma and adenocarcinoma is currently based on the use of a panel of antibodies to adenocarcinoma-associated antigens and a few antibodies to mesothelial-associated antigens. Since the introduction of epitope retrieval methods, the sensitivity of many antibodies has been enhanced. Thus, a reevaluation of the mesothelioma/adenocarcinoma diagnostic panel becomes necessary. We studied 268 paraffin-embedded formalin-fixed tumor samples that included 57 epithelial mesotheliomas and 211 adenocarcinomas of various origins, comparing an extensive antibody panel with and without heat-induced epitope retrieval (HIER). Marked increase in the sensitivity of several antibodies, with no loss of specificity, was found when HIER was used. After statistical analysis, the antibodies to the epithelial glycoproteins carcinoembryonic antigen, BerEp4, and Bg8 emerged as the best discriminators between adenocarcinoma and epithelial mesothelioma within the entire panel. The mesothelium-associated antibodies, HBME-1, calretinin, and thrombomodulin were less sensitive and less specific than the former, although they were found to be useful on certain cases. Antibodies to cytokeratins and vimentin, although of minor diagnostic value in this context, may be helpful to evaluate the quality of antigen preservation. This study confirms the value of immunohistochemistry to accurately distinguish mesothelioma from adenocarcinoma when an antibody panel approach is used. The addition of heat-induced epitope retrieval methods increases the effectiveness of the procedure and is recommended for most of the antibody panel members.

Malignant vascular tumors of the serous membranes mimicking mesothelioma. A report of 14 cases

Malignant endothelial neoplasms involving the serous membranes are rare, and only a few cases have been documented. We report 14 patients with epithelioid hemangioendothelioma (EHE) or epithelioid angiosarcoma (EA) diffusely involving the pleural, peritoneal, or pericardial cavities, resulting in a picture closely resembling mesothelioma. The mean age at diagnosis was 52 (range, 34-85). The patients included two women and one man with peritoneal tumors, eight men with pleural tumors, and three men with pericardial tumors. A shared histological appearance was a diffuse sheet-like and clustered pattern of tumor growth with variable degrees of vascular differentiation. A tubulopapillary growth pattern, often seen in mesothelioma, was prominent in four cases. Nine cases showed a variable number of spindle cells, some neoplastic, others reactive, focally producing a biphasic growth pattern, further suggesting mesothelioma. Initial interpretations included mesothelioma, adenocarcinoma, and, in one case with prominent spindle-cell components, leiomyosarcoma. Immunohistochemically, strong vimentin staining and negative or weak to moderate cytokeratin staining were observed in all 14 cases. The tumor cells coexpressed at least two of the four endothelial markers used in the study (CD31, CD34, von Willebrand factor, and Ulex europaeus agglutinin-I [UEA-I)]. Detection of abortive vessel formation was facilitated by staining for collagen type IV. Markers of mesothelial, epithelial, muscular, and neuronal differentiation were all negative in the subset of cases studied. As a control group, 39 mesotheliomas and more than 60 adenocarcinomas of various origins were studied using the same antibody panel. This group revealed strong keratin staining, moderate or negative vimentin staining, and no expression of any of the endothelial-lineage markers, with the exception of positive staining for UEA-I in occasional adenocarcinomas. Clinically, these endothelial tumors were highly aggressive; 12 patients presented with disseminated disease, and most died within months of the initial presentation. These findings indicate that, although uncommon, EHE/EA should be included in the differential diagnosis of serous membrane neoplasms with histological and clinical features of malignant mesothelioma. The diagnosis of an endothelial neoplasm can be suspected by the presence of abortive vessel formation and by the strong expression of vimentin, with absent or low-level expression of cytokeratin. The demonstration of immunoreactivity for two or more endothelial-associated markers is essential in confirming the diagnosis.

Differential reactivity of HBME-1 and CD15 antibodies in benign and malignant thyroid tumours. Preferential reactivity with malignant tumours

We studied a wide range thyroid tumours and non-neoplastic conditions (total 463 cases) immunohistochemically to evaluate the possible diagnostic potential of HBME-1 and CD15 antibodies. HBME-1 monoclonal antibody recognizes a biochemically unknown epitope present in mesothelioma and variably present in some adenocarcinomas. CD15 antibodies recognize a sugar epitope also included in Lewis X blood group antigen. All papillary (145/145) and follicular carcinomas (27/27) were HBME-1 positive, usually in the the majority of tumour cells. In contrast, cases of nodular goitre and papillary hyperplasia either showed no reactivity or were focally positive (in a third of cases). The patterns of CD15 reactivity were generally similar, although smaller numbers of tumour cells were positive in papillary carcinomas, and only 50% of follicular carcinomas were positive. Because fetal thyroid also showed CD15 reactivity, this antigen appears to behave as an oncofetal antigen in relation to thyroid tissue. Anaplastic carcinomas were negative with both antibodies, indicating the loss of these epitopes upon high grade malignant transformation. We conclude that HBME-1 and CD15 immunohistochemistry may be helpful in the histological differential diagnosis between benign lesions and differentiated thyroid carcinomas, especially papillary tumours. Although the biochemical basis of HBME-1 reactivity is unknown, increased CD15 reactivity in malignant thyroid tumours probably reflects changes in thyroid follicular epithelial glycoconjugates related to malignant transformation.

Malignant epithelial mesothelioma of the peritoneum: observations on a problem case

A 71-year-old asbestos-exposed male with symptoms suggestive of asbestosis for the previous 8 years presented with abdominal distension and ascites. Clinically, a diagnosis of mesothelioma carcinoma was made. Light microscopy of an omental biopsy failed to advance the diagnosis: The tumor was a solid, papillary, and glandular neoplasm lacking mucin and hyaluronidase-sensitive Alcian blue staining material. Immunohistochemistry gave positive results for Ber-EP4, LeuM1, and CEA, markers, favoring carcinoma. Electron microscopy revealed processes in channels and lumina, which were long, slender, and uncoated with a length: diameter ratio of 19.7. A few possessed small rootlets. A glycocalyx and glycocalyceal bodies were not seen. Other features included tonofibrils, a basal lamina, and desmosomes. The patient died 3 months following the onset of abdominal symptoms. Autopsy findings included solid and papillary tumor throughout the peritoneum, but no intrinsic tumor of the gastrointestinal tract or elsewhere. Arriving at a final diagnosis was complicated by immunohistochemistry, which favored carcinoma, and ultrastructure, which suggested mesothelioma. Taking into account all lines of evidence, it was concluded that the tumor was probably a mesothelioma but one with some features developed to an extent more typical of carcinoma.

Expression of CD15 in normal and metaplastic Paneth cells of the digestive tract

AIMS

To substantiate that incubation with monoclonal antibody CD15 (C3D-1) elicits a distinctive immunoreaction in normal small intestinal Paneth cells, normal and metaplastic Paneth cells along the digestive tract were assessed to determine whether they are also immunoreactive to CD15.

METHODS

Paneth cells in paraffin wax embedded specimens of normal small intestine, appendix and proximal ascending colon, and from cases of chronic gastritis and ulcerative colitis were investigated immunohistochemically for lysozyme and CD15 antigen expression by means of the avidin-biotin peroxidase complex method.

RESULTS

CD15 antibody reacted with a high proportion of both normal and metaplastic Paneth cells. Paneth cell immunoreactivity to CD15, however, was less intense and less extensive than to antilysozyme antibody, though the latter also stained many other cell types and was more commonly associated with nonspecific background staining.

CONCLUSIONS

CD15 seems to be a valuable adjuvant for the study of Paneth cells in the normal and diseased digestive tract. Furthermore, as CD15 has been shown to be involved in activation of phagocytes, its expression in Paneth cells reinforces their proposed role as antimicrobial agents and regulators of the intestinal flora.

Significance of epithelial membrane antigen in the work-up of problematic serous effusions

Differentiation of reactive and/or atypical mesothelial cells from malignant epithelial cells in serous effusions remains a frequent diagnostic problem. Since epithelial membrane antigen (EMA) positive malignant cells in serous effusions have been reported in almost all adenocarcinomas and most malignant mesotheliomas, immunoreactivity for EMA is felt to be less useful than other antibodies in the workup of problematic serous effusions. However, immunostaining of reactive and/or atypical benign mesothelial cells for EMA has not been well studied, with only a few series reporting either weak or negative staining for EMA. This study was undertaken to evaluate how often reactive and/or atypical appearing mesothelial cells stain positively for EMA. One hundred eighty serous effusions (115 pleural, 55 peritoneal, and 10 pericardial) from 123 females and 57 males ages 20 to 89 yr were evaluated in which an antibody panel including EMA was performed on cell blocks (141 cases), cytospins (36 cases), or both (3 cases). Of the 100 cytologically positive cases, EMA immunoreactivity was present in 97/100 (97%) cases. One EMA negative case suspicious for a metastatic renal cell carcinoma was lost to follow-up and not included in the analysis. The remaining three negative cases consisted of malignancies not expected to have EMA positive cells (small cell carcinoma, neuroblastoma, and synovial sarcoma). Therefore, EMA was positive in virtually 100% of the remaining malignant cases. In the 78 cytologically negative cases, EMA positivity was present in 3/78 (3.8%) cases. Clinical follow-up of up to 14 mo in these three cases revealed no evidence of malignancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical characterization of malignant mesothelioma and carcinoma metastatic to the pleura: IOB3--a new tumor marker

We have tried to find a reliable panel of markers that would allow distinction between mesotheliomas and carcinomas metastatic to the pleura. In a prospective study, we evaluated 54 pleural effusions: In 27 of the patients, a diagnosis of histologically proven metastatic carcinoma was subsequently established, 7 patients had biopsy-proven malignant mesotheliomas and 20 had benign, reactive effusions whose benign etiologies were established by more than 2 years clinical follow-up. The MAb (monoclonal antibody) IOB3 proved to be diagnostic for carcinomas in all 27 cases (100%), whereas CEA (carcinoembryonic antigen) expression was found in only 22 out of 27 (81%). None of the malignant mesotheliomas, nor benign reactive mesothelial cells reacted with these two markers. All carcinomas, as well as one malignant mesothelioma, reacted with the MAb HEA125. Antibodies against 12 single cytokeratins, vimentin, and EMA (epithelial membrane antigen) were not helpful in the differentiation between malignant mesotheliomas and malignant carcinomatous pleural effusions. We conclude that adding the antibody IOB3 to the CEA assay should allow a reliable differentiation between these two entities.

The value of immunohistochemistry of pleural biopsy specimens in the differential diagnosis between malignant mesothelioma and metastatic carcinoma

The aim of the present study was to evaluate the aid of immunohistochemistry in the differential diagnosis between pleural malignant mesothelioma (MM) and secondary pleural carcinoma in pleural biopsy specimens. A series of MM (epithelial or biphasic type) (n = 39), and a series of secondary pleural carcinomas (n = 25) were studied with a panel of monoclonal antibodies against Ber-EP4, CEA, and Leu-MI (CD-15). Considering the markers one, two or three at a time, computer analysis was conducted to identify the immunophenotype with the highest sensitivity and specificity for both MM (n = 39) and adenocarcinoma (n = 19). The CEA/CD-15 marker combination had the highest specificity (MM = 100%; adenocarcinoma = 82.1%), and sensitivity (MM = 82.1%; adenocarcinoma = 100%) considering both categories of tumours. Positive reaction for CEA and/or CD-15 was the best indicator of metastatic adenocarcinoma. Negative reaction for CEA/CD-15 and Ber-EP4/CD-15 showed up to be 100% specific for MM. Positive reaction for one, two or even all these antigens, however, occurred in nine tumours predetermined as MM according to their gross appearance, and absence of other primary malignancies at autopsy. Ultrastructural examination (n = 7) of these tumours strongly supported the diagnosis in one case, and did by no means exclude the diagnosis MM in the other six cases. Neither did any of the tumours reveal ultrastructural signs of adenomatous differentiation, and they did not express PAS/diastase resistant globules, amylase or surfactant. Anti -Ber-EP4 was the antibody most frequently expressed in MM (n = 8). Until antibodies specific for MM are available, the limitation of immunohistochemistry to solve the diagnosis in all cases of pleural malignant tumours has to be considered.

Differentiation of adenocarcinoma of the lung and malignant mesothelioma: predictive value and reproducibility of immunoreactive antibodies

A panel of antibodies against keratins, epithelial membrane antigen (EMA), epithelial antigen (Ber-EP4), carcinoembryonic antigen (CEA), tumour-associated glycoprotein (B72.3), vimentin and LeuM1 was applied to sections of adenocarcinoma of the lung and malignant mesothelioma in a randomized design. The proportion of stained tumour cells within each section was estimated independently in five categories by three pathologists (no positive tumour cells, 1-10%, 11-33%, 34-66% and more than 67% positive tumour cells). The kappa values representing the chance corrected interobserver agreement for the different antibodies in such a five group assessment were between 0.38 and 0.72. In two group assessment the kappa values were between 0.53 and 0.94. Nosological sensitivity and nosological specificity were calculated for all antibodies, and diagnostic sensitivity and diagnostic specificity (predictive values) were calculated for the Ber-EP4, CEA, B72.3, LeuM1 and vimentin. The difference between nosological sensitivity and nosologic specificity and the clinically relevant predictive values of positive and negative tests were demonstrated. In respect of the reproducibility and the diagnostic power defined by the predictive values, we demonstrated that a panel of antibodies, including CEA, Ber-EP4 and B72.3 and, to a lesser degree, LeuM1 and vimentin is applicable for the histopathological distinction between adenocarcinoma of the lung and malignant mesotheliomas. Before introduction of new diagnostic tests, including new antibodies, the prevalence of the tested tumours should be estimated. Nosological sensitivity and nosological specificity should be converted to predictive values.

The histopathological diagnosis of malignant mesothelioma v. pulmonary adenocarcinoma: reproducibility of the histopathological diagnosis

In a randomized design we examined the interobserver variation in the histopathological diagnosis of adenocarcinoma of the lung and malignant mesothelioma. In three rounds, three pathologists assessed slides from 42 tumours originally diagnosed as adenocarcinomas, malignant mesotheliomas or benign lesions in the pleura. In the first round the assessments were made on haematoxylin and eosin (H & E) stained sections; in the second, on H & E sections plus sections stained with histochemical mucin stains; and in the final round, the diagnoses were made on H & E sections and sections stained with a panel of antibodies against various antigens (cytokeratin, EMA, CEA, Ber-EP4, B72.3, Leu-M1, vimentin and S-100 protein) said to be of value in the differential diagnosis. The overall interobserver agreements for the three rounds were 0.659, 0.802 and 0.817; the kappa values were 0.461, 0.681 and 0.690. It is concluded that differentiation between adenocarcinoma of the lung and malignant mesothelioma should be made on sections stained with H & E and mucin and/or immunohistochemical staining reactions, including antibodies against B72.3, Ber-EP4 and CEA.

Immunohistochemical reactivity in mesothelioma and adenocarcinoma: a stepwise logistic regression analysis

Histological sections from 103 malignant mesotheliomas and 43 adenocarcinoma metastases in pleural biopsies were investigated for reactivity against a panel of 11 different antibodies. The size of the material allowed the evaluation by stepwise logistic regression analysis, which selected five parameters of major importance: vimentin reactivity in epithelial cells, reactivity to low-molecular-weight keratins in fibrous cells, strong membrane accentuation of EMA reactivity, and lack of reactivity to LeuM1 and BerEp4. Three of these criteria were sufficient to identify a mesothelioma with high specificity and with a sensitivity of approximately 70%. Whilst the monoclonal anti-CEA tested was the most valuable single parameter, it did not add any diagnostic information to the combination of criteria selected by the stepwise logistic regression analysis. However, this antibody can be used to exclude most of the adenocarcinomas from further analysis with the more extensive panel.

Immunocytochemical characterization of cell lines from human malignant mesothelioma: characterization of human mesothelioma cell lines by immunocytochemistry with a panel of monoclonal antibodies

A panel of nine monoclonal antibodies was used to characterize human mesothelioma cell lines that we established from human malignant mesothelioma. The antigens detected were cytokeratin, vimentin, epithelial membrane antigen, carcinoembryonic antigen, Leu-M1 (CD15), desmin, factor VIII-related antigen (von Willebrand factor antigen), OV632, and ME1, a specific monoclonal antibody directed against human malignant mesothelioma. The technique used was the alkaline phosphatase anti-alkaline phosphatase method. All 30 cell lines, either epithelial, sarcomatous, or mixed, showed strong reactivity with cytokeratin and vimentin antibodies. None of the cell lines demonstrated any reactivity with carcinoembryonic antigen, Leu-M1, or factor VIII antibodies; moreover, all of 22 cell lines studied were positive for ME1 antibody and 10 of 12 cell lines studied were positive for OV632. Some interesting features were noted: only two of the 30 cell lines presented a weak positive staining with epithelial membrane antigen, and nine of 19 cell lines tested demonstrated a cytoplasmic staining pattern with desmin antibody. These results show that established human mesothelioma cell lines still possess the immunocytochemical characteristics that are basically consistent with the immunohistochemical features described in tumor tissues of malignant mesothelioma. These characteristics can be used to identify the mesothelioma cells grown from human malignant mesothelioma. Hence, the mesothelioma cell lines will provide a useful tool for the investigation of the cell biology of the tumor and the mechanisms of mesothelial cell transformation, as well as the in vitro evaluation of the effects of some drugs in order to develop new therapies for malignant mesothelioma.

Monoclonal antibody Ber-EP4: its use in the differential diagnosis of malignant mesothelioma and carcinoma in cell blocks of malignant effusions and FNA specimens

Formol sublimate-fixed cell blocks derived from 129 malignant pleural (and some peritoneal) effusions, 8 benign effusions with reactive mesothelial cells, and 23 FNA specimens, were immunostained with monoclonal antibody Ber-EP4 to assess its ability to distinguish malignant mesothelioma (MM) from carcinoma. Only 2 of 44 (4%) well-characterized MM were Ber-EP4+, while none of 8 benign mesothelial proliferations reacted with the antibody. Fifty-seven percent of 23 pulmonary adenocarcinomas (AC) and 60% of 43 pulmonary carcinomas of all other histological types were Ber-EP4+. Of 40 metastatic AC originating from breast, gastrointestinal tract, ovary, endometrium, and kidney, 80% were Ber-EP4+. The predictive value of positive Ber-EP4 staining in distinguishing AC from MM was 96%. The predictive value of a negative Ber-EP4 in excluding MM was 70%, when the differential diagnosis was adenocarcinoma. These results suggest that Ber-EP4 is helpful in differentiating MM and AC if used together with other discriminating antibodies.

Metastatic mesothelioma of the oral cavity. Report of two cases

Malignant mesothelioma is an aggressive neoplasm originating from the serosal surfaces of the pleural or peritoneal cavity. The following article describes two cases of metastatic mesothelioma to the oral cavity; one involves the tongue, the other involves the mandible. The diagnostic criteria for differentiating metastatic mesothelioma from adenocarcinoma are also discussed.

Reactivity of B72.3 with adenocarcinomas. An immunohistochemical study of 476 cases

BACKGROUND

The monoclonal antibody B72.3 has been shown to react with several common types of adenocarcinoma. However, the distribution of B72.3 reactivity in adenocarcinomas has not been well-enough defined to determine whether B72.3 immunostaining would be helpful in the diagnosis of adenocarcinoma of unknown origin.

METHODS

Formaldehyde fixed, paraffin-embedded tissue from 476 adenocarcinomas from a variety of primary sites were studied using B72.3 and an avidin-biotin complex immunohistochemical technique.

RESULTS

B72.3 immunoreactivity was seen in 75-100% of the adenocarcinomas from the ovary, endocervix, endometrium, distal esophagus/stomach, colon, lung, breast, prostate, pancreas, and bile ducts. Positive reactions were unusual in thyroid carcinomas (7%) and renal cell carcinomas (11%). B72.3 reactivity was not seen in the 20 hepatocellular carcinomas or 4 adrenal cortical carcinomas studied.

CONCLUSIONS

B72.3 reacts with a wide variety of adenocarcinomas. Immunostaining with B72.3 may be helpful in excluding hepatocellular carcinoma in certain clinical settings.

Comparison of monoclonal antibodies AUA1 and BER EP4 with anti-CEA for detecting carcinoma cells in serous effusions and distinguishing them from mesothelial cells

Commercially available monoclonal antibodies AUA1, BER EP4 and carcinoembryonic antigen (CEA) were applied to cell blocks from 95 serous effusions. AUA1 and BER EP4 were reactive with 89% of effusions known to contain carcinoma cells, and anti-CEA with 71%. They also reacted with cells in two effusions from patients with malignant disease which were regarded as negative on conventional cytological examination of Papanicolaou-stained smears. They were negative in all but one of the benign effusions. Using all three antibodies, 95% of effusions containing carcinoma cells were detected. Use of these antibodies could improve the cytological diagnosis of serous effusions.

Multiple-marker immunohistochemical phenotypes distinguishing malignant pleural mesothelioma from pulmonary adenocarcinoma

The diagnostic distinction between malignant pleural epithelial mesothelioma and pulmonary adenocarcinoma is often difficult and partially reliant on the use of immunohistochemistry (IHC). While there are several available IHC markers preferentially expressed in adenocarcinomas compared with mesotheliomas, there are no readily available or well-validated markers preferentially expressed in mesotheliomas and no markers are absolutely specific for either tumor. Thus, there always will be an element of doubt regarding the identity of lesions diagnosed by IHC using these markers and an undesirable reliance on negative results if the lesion is truly a mesothelioma. To help optimize the ability of currently available but imperfect markers to resolve adenocarcinoma and mesothelioma and to minimize the impact of false-negative results on their diagnosis, a systematic study was undertaken to identify multiple-marker immunostaining phenotypes that are the most specific and sensitive for each type of tumor. The study involved staining a series of malignant epithelial mesotheliomas (n = 34) and pulmonary adenocarcinomas (n = 103) with eight markers that were selected on the basis of previous reports of their relatively restricted specificities for one or the other of these lesions (and included carcinoembryonic antigen [CEA], tumor-associated glycoprotein 72 [B72.3], Leu-M1, vimentin, thrombomodulin, secretory component, carcinoma antigen-125, and periodic-acid-Schiff with diastase [for mucin]. Considering the markers one, two, and three at a time, all possible combinations of results were analyzed by computer to identify the phenotype most sensitive and specific for adenocarcinoma or mesothelioma. The best single marker was CEA (positive: 97% specific and sensitive for adenocarcinoma; negative: 97% specific and sensitive for mesothelioma). However, because examples of both tumor types expressed CEA, none of the study cases were unequivocally resolved and the risk of false-negative results was relatively high. The best two markers were CEA and B72.3 (both positive: 100% specific and 88% sensitive for adenocarcinoma; both negative: 99% specific and 97% sensitive for mesothelioma). The four possible combinations of results for these two markers resolved 68% of cases (93 of 137 cases), with less risk of false-negative results than a single marker. In general, several three-marker panels resulted in sensitivities and specificities similar to the two-marker panel of CEA and B72.3. In particular, the three-marker panel of CEA, B72.3, and Leu-M1 resulted in eight possible phenotypes that resolved 74% of cases (101 of 137 cases), with even further reduced risk of false-negative results.(ABSTRACT TRUNCATED AT 400 WORDS)

Definition of the expression of the human carcinoembryonic antigen and non-specific cross-reacting antigen in human breast and lung carcinomas

Mouse cell lines transfected with carcinoembryonic antigen (CEA) and with 2 other members of the human CEA gene family, non-specific cross-reacting antigen (NCA) and biliary glycoprotein (BGP), were used to analyze the specificity of several monoclonal antibodies (MAbs). MAbs COL-1 and COL-6 were shown to react with the transfected CEA gene product but not with NCA, confirming previous results. Cells expressing the transfected BGP gene product also failed to react with COL-1 and COL-6. The MAb B6.2 reacted with cells expressing the NCA gene product but not with those expressing CEA or BGP. The MAb B1.1 reacted strongly with the transfected CEA and BGP gene products but only weakly with the NCA gene product. These antibodies were then utilized in the histochemical analysis of a number of primary and secondary breast and lung tumors. The results indicate that a majority of breast and lung tumors express CEA, and nearly all breast and lung tumors express NCA. Fairly homogeneous expression of CEA and NCA was seen in the majority of both breast and lung tumors. Our results indicate that CEA may be an important target for immunotherapy in a large number of patients with breast and lung tumors.

Diagnostic tools for differentiating between pleural mesothelioma and lung adenocarcinoma in paraffin embedded tissue. Part I: Immunohistochemical findings

Specimens of 27 histologically definite mesotheliomas and 34 proven adenocarcinomas were examined with a panel of 14 antibodies: pan-epithelial antibody Lu-5, anti-keratin-18, anti-keratin-7, Ber-EP4, anti-Leu-M1, HEA-125, anti-carcino-embryonic antigen (CEA), anti-blood group-related antigens (anti-BGR A, B, H), B72.3, anti-placental alkaline phosphatase (PLAP), anti-vimentin and BMA-120 used to determine their value in the differentiation between pleural mesothelioma and lung adenocarcinoma. Lu-5, anti-cytokeratin-7 and -18, B 72.3 and PLAP reacted in a high percentage of cases with both mesothelioma and adenocarcinoma. Anti-CEA and anti-Leu-M1 did not react with any of the 27 mesotheliomas tested but showed a reaction in 75% (anti-CEA) and 66% (anti-Leu-M1) of the lung adenocarcinomas. Seventeen percent of the adenocarcinomas and 96% of the mesotheliomas showed a positive reaction with anti-vimentin. Ber-EP4 was demonstrated in all lung adenocarcinomas, but only in 2 mesotheliomas in a focal manner (7%). HEA-125 and anti-BGR A, B, H reacted with 83% (HEA-125) and 75% (anti-BGR A, B, H) of the lung adenocarcinomas. The statistical parameters, sensitivity and efficiency were estimated and a normogram for judging the diagnostic power of a single antibody for the differential diagnosis of mesothelioma versus adenocarcinoma was developed. According to this, Ber-EP4, HEA-125, anti-BGR A, B, H and anti-CEA were, in descending order, the most powerful discriminatory antibodies.

Cytopathology of malignant mesothelioma: a study of its patterns and histological bases

We have reviewed the effusion cytology of 51 cases of histologically proven malignant mesothelioma of the pleura (49 cases) and the peritoneum (2 cases). The patient group included 45 males and 6 females, aged 45-83 yr. A cytological diagnosis of malignancy had been rendered on 43 cases, and in 30 of them it was consistent with, or at least suggestive of, a mesothelioma. Diagnostic clues, especially evident in epithelial and biphasic tumors were hypercellularity and/or morular aggregates of malignant cells showing scalloped borders and nuclei with dense chromatin and evident nucleoli. Cytomegaly with multinucleation was also frequently observed. Reactive mesothelial cells were often present along with other non specific features such as red blood cells, fibrin, necrotic debris. In 13 cases, a diagnosis of malignancy was entertained but mesothelioma, although considered, was not reported out because of scantiness of material. In four cases, adenocarcinoma was erroneously diagnosed for the presence of deceptive cell vacuoles. In eight cases, no diagnostic cells were recovered in repeated effusions. The first diagnosis was a cytologic one in 37 patients, Tissue study was performed on autopsy (35 patients) and surgical material. The latter was the only source of histology in six cases. Immunocytochemical investigation was negative for carcinoembryonic antigen in all but one tested cases (1/21) and positive for human milk fat globulin in about one-half of the epithelial and biphasic tumors. In 18 of 21 cases, positivity for combined high- and low-molecular-weight keratins was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Pleural malignant fibrous histiocytoma concomitant with pulmonary adenocarcinoma

A rare autopsy case, in which pleural malignant fibrous histiocytoma (MFH) and peripheral pulmonary adenocarcinoma were present concurrently in the right thorax, is described. Clinically, only a pleural mass was detected because of massive pleural effusion. Since cytologic examination of the effusion showed only adenocarcinoma cells, the pleural mass was considered to be enlarged mediastinal lymph nodes due to metastasis of adenocarcinoma. Histopathologically, the pleural mass showed the features of a common type of MFH, accompanied by metastatic adenocarcinoma cells in the pleural lymphatics. No mixture of MFH and adenocarcinoma cells was present. Immunohistochemically, the MFH lesion showed positive staining for alpha-1-antitrypsin, alpha-1-chymotrypsin, and factor XIIIa, but no reactivity for cytokeratins. The adenocarcinoma lesion showed positive staining for carcinoembryonic antigen (CEA), and contained hyaluronidase-resistant mucin. To our knowledge, this is the second reported case of pleural MFH with pulmonary adenocarcinoma.

NEU protein overexpression in benign, borderline, and malignant ovarian neoplasms

In situ hybridization (ISH) analysis of 24 benign, borderline, and malignant ovarian tumor specimens revealed NEU transcript expression by epithelial elements in approximately two-thirds of the samples and high-level expression in 3 grade 3 adenocarcinomas. Immunohistochemical staining (IHC) of a total of 86 specimens (including 17 of those studied by ISH) localized NEU antigen expression to epithelial cells in 36 of 86 samples with strong membrane staining observed in 12, including 1 benign, 1 borderline serous carcinoma, 3 clear cell/endometrioid carcinomas, and 7 predominantly papillary serous carcinomas with areas of clear cell/endometrioid histology. Clinical correlation of the IHC results for the 72 Stage I-IV invasively malignant neoplasms revealed no statistically significant association of the intensity of NEU IHC staining with either relapse-free or overall survival. However, more of the patients whose tumors showed strong membrane staining for NEU antigen suffered relapses of disease by 3 and 4 years than did patients whose tumors showed weak or no membrane staining. These results suggest a role for the NEU gene product in the physiology of benign ovarian surface epithelium and the neoplastic epithelium of preinvasive borderline and some invasively malignant adenocarcinomas.

The utility of ancillary techniques in effusion cytology

We believe that, in general, immunocytochemical studies when used as a panel are the most helpful of the ancillary techniques in the workup of a difficult effusion cytology case. Routine histochemical stains for mucin should also be employed due to their low cost and simplicity, but suffer from lack of sensitivity and specificity. EM examination is especially helpful in the differentiation of metastatic carcinoma from mesothelioma, but lacks specificity due to overlapping ultrastructural features, and is both costly and labor intensive. Immunophenotyping by flow cytometry is useful in the workup of problematic lymphoid proliferations, but DNA analysis by flow cytometry is not useful as a screening technique. Fortunately, most effusion cytology cases will not need the use of ancillary studies, since the diagnosis will be accurately rendered based on the cytomorphologic findings. However, occasional cases will benefit from the use of specific ancillary studies, which can aid in making an accurate, specific, and rapid diagnosis in an otherwise challenging case.