The use of vimentin antibodies in the diagnosis of malignant mesothelioma

Summary An immunohistochemical investigation of vimentin, an intermediate filament, was carried out on formalin fixed paraffin embedded sections of 44 malignant mesotheliomas of the pleura and 24 pulmonary adenocarcinomas, in order to assess its value in differential diagnosis. Seventy-five percent of the malignant mesotheliomas showed positive staining for vimentin. An unexpected finding was the presence of vimentin tin in 46% of the pulmonary adenocarcinomas. In either case there was no correlation between the presence of vimentin and the histological types or grades of differentiation. The overall level of vimentin staining was significantly greater in the malignant mesotheliomas than in the pulmonary adenocarcinomas but no single antibody dilution was found to provide clear cut separation of the two groups. Vimentin does not appear to be a simple discriminatory marker of 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

Formal 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. © 1994 Wiley-Liss, Inc.     

The influence of the diagnostic technique on the histopathological diagnosis in malignant mesothelioma

Summary In the histopathology of malignant mesotheliomas three different types (epithelial, connective tissue and mixed type) are distinguished. Some authors believe all tumours to be of mixed type, but consider that due to inadequate sampling or small biopsies this may be missed frequently. In this study the relationship between the histopathological diagnosis and the amount of tissue examined was investigated. In a series of 124 cases of malignant pleural mesothelioma a high percentage of mixed type tumours was found (55%). In cases where the decisive diagnostic procedure had been an Abrams biopsy (the small-specimen technique) mixed-type histology was found in 36%. If thoracoscopy, thoracotomy or autopsy (the large-specimen techniques) had delivered a definite diagnosis, mixed-type histology was found in 63%. Apparently diagnosing the mixed-type variety depends on the amount of tumour tissue obtained. However, the assumption that all mesotheliomas are of mixed type cannot be confirmed.     

BAP1 immunohistochemistry and p16 FISH results in combination provide higher confidence in malignant pleural mesothelioma diagnosis: ROC analysis of the two tests

Differentiation of malignant pleural mesothelioma (MPM) from benign mesothelial proliferation remains problematic. Loss of nuclear staining of BRCA1‐associated protein 1 (BAP1; detected using immunohistochemistry (IHC)) and homozygous deletion (HD) of p16 (detected using fluorescence in situ hybridization (FISH)) are useful for differentiation of MPM from reactive mesothelial hyperplasia (RMH), but the correlation between BAP1 expression loss and p16 HD has not been fully described. We performed BAP1 IHC and p16‐specific FISH for 40 MPM and 20 RMH cases, and measured proportions of cells showing BAP1 expression and p16 HD for each case. The diagnostic accuracy for MPM and the cut‐off values of the two methods were assessed using receiver operating characteristic (ROC) analysis. BAP1 expression loss, p16 HD and coexistence of both were present in 27 (67.5 %), 27 (67.5 %) and 17 (42.5 %) MPM cases, respectively. Three MPM cases (7.5 %) and all 20 RMH cases had neither BAP1 loss nor p16 HD. There was no correlation between the results of the two methods. Their combination showed higher sensitivity (92.5 %, 37/40) and estimated probability than BAP1 IHC and p16‐specific FISH used alone. BAP1 IHC and p16‐specific FISH have independent diagnostic value, and have increased reliability when used in combination, for MPM diagnosis.     

Expression of inhibitor-of-apoptosis protein family members in malignant mesothelioma

Inhibitor-of-apoptosis proteins (IAPs) mediate cancer cell survival and chemoresistance. We analyzed the expressions of X-linked IAP (XIAP), survivin, and livin in malignant mesothelioma. Ten effusions were analyzed for XIAP, survivin, and livin expression using immunoblotting. Based on the immunoblotting results, 112 mesotheliomas from 94 patients (pleural, n = 77; peritoneal, n = 35; solid, n = 68; effusions, n = 44) were immunostained for XIAP and survivin expression. Results were analyzed for associations with anatomic site (pleura versus peritoneum), specimen type (solid versus effusion), proliferation (Ki-67 score), and survival. Immunoblotting showed expression of XIAP in 9 of 10 effusions and that of survivin in 4 of 10 effusions, but no expression of livin. Immunohistochemistry showed cytoplasmic XIAP expression in 71 of the 112 (63%) tumors. XIAP expression was significantly higher in peritoneal mesotheliomas than in pleural mesotheliomas (P = .001) and in effusions than in solid lesions (P = .017). Cytoplasmic survivin was found in 75 of the 112 (67%) tumors and showed no site-related difference. Nuclear survivin was expressed in 37 of the 112 (33%) tumors, with a trend for positive association with the Ki-67 score (P = .051). Nuclear survivin (P = .003) and Ki-67 (P = .013) were downregulated in effusions as compared with solid tumors. Higher XIAP expression and Ki-67 score were associated with a trend for poor overall survival (P = .064 for both) in the univariate analysis. XIAP and survivin, but not livin, are frequently expressed in malignant mesotheliomas. Nuclear survivin expression is reduced in effusions as compared with solid lesions concomitantly with reduced proliferation. XIAP is upregulated in mesothelioma effusions and peritoneal mesotheliomas, suggesting a prosurvival role in malignant mesothelioma cells, particularly at these anatomic sites.     

Expression of HLA-G in malignant mesothelioma and clinically aggressive breast carcinoma

The aim of the present study was to evaluate HLA-G expression in breast carcinoma and malignant mesothelioma (MM). Malignant breast carcinoma effusions (46) and corresponding solid tumors (39) and 104 MM (26 effusions, 78 solid tumors) were analyzed using immunohistochemistry (IHC). HLA-G protein and mRNA expression were further studied using immunoblotting (IB) and RT-PCR. HLA-ABC expression was analyzed using flow cytometry (FCM). IHC showed predominantly focal HLA-G expression in 12 of 46 (26%) breast carcinoma effusions and 16 of 39 (41%) solid lesions. In MM, 20 of 78 (26%) solid lesions and 14 of 26 (54%) effusions were focally HLA-G positive. Expression in MM was higher in effusions (p=0.008). IB showed more frequent HLA-G expression in MM compared with breast carcinoma effusions, while RT-PCR showed HLA-G mRNA expression in both tumors. FCM showed conserved HLA-ABC expression in 15 of 15 effusions. Breast cancer patients with HLA-G-positive tumor cells had shorter disease-free survival (mean 37 vs 85, median 25 vs 31 months), though not significantly (p=0.14). In conclusion, HLA-G is focally expressed in MM and breast carcinoma, while HLA-ABC expression is conserved. However, the up-regulated expression of HLA-G in MM effusions and its possible association with shorter disease-free survival in advanced stage of breast carcinoma suggest a possible role in immune response evasion in some tumors.     

Pathology of malignant mesothelioma

The diagnosis of malignant mesothelioma can pose several problems to the surgical pathologist. First, the morphological appearances of the tumour are known to be diverse with mimicry of a range of both reactive and neoplastic conditions. Second, due to the relative inaccessibility of the serosa, biopsy material is often scanty and fragmentary, producing a plethora of interpretive ambiguities. Third, adjunct techniques such as mucin histochemistry and immunohistochemistry, whilst useful in excluding malignant mesothelioma have little role in confirming the diagnosis. The accurate diagnosis of diffuse malignant mesothelioma is important for two reasons: (1) In relation to prognosis as it has an almost invariable fatal outcome, which contrasts with the other mesothelial neoplasms such as the benign adenomatoid tumour and the borderline malignant tumours, namely the well-differentiated papillary mesothelioma and multicystic mesothelioma; (2) In relation to occupational-related compensation claims following asbestos exposure. This review summarizes the aetiology of asbestos-induced neoplasia, possible mechanisms of tumour development and highlights potential diagnostic pitfalls.     

Role of fragile histidine triad protein expression in pathogenesis of malignant pleural mesothelioma

AIM:To investigate the relationship of fragile histidine triad (FHIT) and Ki-67 expression with clinicopathological variables of patients with malignant pleural mesothelioma (MPM). METHODS: Formalin-fixed, paraffin-embedded tissue sections of 30 asbestos induced MPM (epithelial and biphasic) patients were examined for FHIT and Ki-67 expression using immunohistochemical techniques and results were compared with clinicopathological variables. RESULTS: Immunohistochemical study results were as follows: 12 (40%) cases showed low FHIT expression and 18 (60%) showed high expression. There was no significant relationship between FHIT and age, gender or histological subtypes (p > 0.05). Ki-67 expression was 'low' in 13 (43.3%) cases and 'high' in 17 (56.7%) cases. No correlation could be demonstrated between Ki-67 expression and age, gender or histological subtypes (p > 0.05). No significant association was observed between FHIT and Ki-67 expression in MPM. CONCLUSION: The results support the role of FHIT as a tumour suppressor gene in asbestos induced MPM. There is no significant correlation between FHIT and cell proliferation marker expressions in malignant pleural mesothelioma. Therefore, it can be concluded that loss of FHIT does not interfere with tumour proliferation. This can be accepted as evidence for an early role of FHIT loss in carcinogenesis; however, it needs to be strengthened by further studies.     

Localized malignant mesothelioma of the pleura

We describe a case of malignant pleural mesothelioma appearing as a solitary pleural tumor in a 56-year-old Japanese man with no history of exposure to asbestos. A chest radiograph revealed an isolated extrapulmonary mass in the left hemithorax. The patient underwent tumor resection, but the tumor later recurred on the contralateral pleura. The patient developed cerebral metastases and died 16 months after the initial surgery. The resected tumor was sessile with broad-based pleural attachment. Microscopically, the tumor was composed of interlacing fascicles of plump spindle cells intermixed with few polygonal cells. Most of the tumor cells showed positive immunoreactivity for cytokeratins (AE1 and AE3) and vimentin. Many of the tumor cells were positive for epithelial membrane antigen, and a few were positive for desmin. In contrast, the tumor cells were consistently negative for carcinoembryonic antigen, epithelial antigen BerEP4, calretinin, S-100 protein, neuron-specific enolase, muscle actin antigen HHF35, alpha-smooth muscle actin antigen and CD34. Ultrastructurally, the tumor cells had diffusely distributed cytoplasmic intermediate filaments, desmosome-like junctions, and a few microvilli. Some tumor cells contained cytoplasmic tonofilaments. Immunohistochemical and ultrastructural findings supported the mesothelial nature of the tumor, and led us to diagnose this tumor as a sarcomatoid localized malignant mesothelioma.     

Hyaluronan synthase expression in pleural malignant mesotheliomas

Hyaluronan (HA) is thought to play several important roles in tumor growth, tumorigenicity, and tumor dissemination and metastasis. Recently, three isoforms of hyaluronan synthase (HAS) have been cloned. Our objective was to determine which of the HAS isoforms were expressed in pleural malignant mesotheliomas, the most representative lesion of HA-producing tumors. We studied 10 cases of pleural malignant mesothelioma using novel antibodies of HAS. We compared HAS expression patterns of mesothelioma and pulmonary adenocarcinoma. Immunohistochemically, 9 of 10 (90%) cases of mesothelioma had extensive reaction to anti-HAS1 and anti-HAS2 antibodies, while HAS3 overexpression was present in 4 of 10 cases (40%). Of 20 cases of pulmonary adenocarcinoma, 5 overexpressed HAS1 (25%), 16 of 20 HAS2 (80%), and 4 of 20 HAS3 (20%). The expression level of HAS1 was significantly higher in mesotheliomas than in pulmonary adenocarcinoma (P=0.0036). Our data suggests that HAS1 might be a useful positive marker of malignant mesothelioma. However, a definitive conclusion should be based on further large-scale studies.     

Localized pleural malignant mesothelioma

The occurrence of pleural malignant mesothelioma (MM) is unusual and the cases that appear as a localized tumor are extremely rare. A case of localized pleural MM including immunohistochemical findings is presented. A 70-year-old man had an abnormal shadow found during a routine roentgenogram at an annual health checkup and was admitted to Toneyama National Hospital (Toyonaka, Osaka, Japan) for detailed examinations. Chest X-rays showed a 2 x 5 cm-sized nodule with relatively smooth margins in the right segment three. Computed tomography (CT) showed an extrapleural mass with a smooth surface and a thickened parietal pleura, and results of a biopsy performed under CT scanning yielded MM. Systematic examinations did not show any metastasis and the patient underwent surgery for removal of the mass. The resected tumor, measuring 3.2 x 3.1 cm, was firm, partially encapsulated, and irregularly shaped. Pathological examinations revealed that it consisted of large polygonal cells, partially showing myxoid patterns, which led to a diagnosis of localized pleural MM. Tumor recurrence was seen, and the duration between initial symptoms and death was 29 months. This case suggests that localized pleural MM has a high proliferative potential and aggressive course, and is considered an early stage of diffuse pleural MM.     

The sensitivity of cytologic evaluation of pleural fluid in the diagnosis of malignant mesothelioma

Pleural malignant mesothelioma (MM), which is an aggressive neoplasm with a high mortality, frequently manifests initially as pleural effusions. The sensitivity of cytologic examination for its diagnosis varies widely in literature and most of the figures are from earlier studies with conventional cytologic preparations. The objective of this study was to provide the current evidence on the role and sensitivity of cytologic examination of pleural fluid in the diagnosis of MM. We reviewed the cytologic findings in pleural effusions of a large series of histologically proven MM (234 cases) diagnosed in our institution between 2001 and 2008. Of all cases, 154 (66%) had cytologic material examined. A specific diagnosis of MM was rendered or suspected in 53% (79 patients). The lowest sensitivity (20%) was noticed in sarcomatoid MM cases. MM was favored over adenocarcinoma in 97% of patients with positive cytologic findings that have been confirmed with immunohistochemistry. In this series, five cases were inadequate and five cases were initially reported as atypical, whereas 65 cases (44%) were reported as negative for malignancy. On review of the cytology slides, only four cases were upgraded from benign to suspicious compared to four cases downgraded from suspicious to atypical but no significant improvement to the diagnosis could be made on revision. These data suggested that a cytologic diagnosis contributed useful information in patients with epithelioid and biphasic pleural MM. Limitations of the cytologic examination of MM should also be acknowledged. Diagn. Cytopathol. 2010;38:874–879. © 2010 Wiley‐Liss, Inc.     

Desmoplastic malignant mesothelioma: two cases and a literature review

We present two cases of desmoplastic malignant mesothelioma (DMM) with pathological, immunohistochemical, and ultrastructural features. Each patient showed rapid progress and died within 1 year from appearance of the initial symptoms. Macroscopically, both showed a thickened pleura replaced by a tumor that encased the lung. Microscopic results of each showed that the tumors consisted of a dense fibrous area, with mild nuclear irregularities and hyperchromatism. In case 1, the tumor had invaded the diaphragm, chest wall, and cardiac sac; the mass in case 2 invaded the lung and diaphragm, and distal metastases were seen in the thoracic vertebrae, meninges, and liver. Ultrastructural findings in case 1 showed a few short blunt microvilli on the cell surfaces. DMM is occasionally difficult to distinguish from fibrous pleurisy and solitary fibrous tumor. Immunohistochemical examinations of the present cases showed the expression of cytokeratin and vimentin, and focal positive stainings of antihuman mesothelial cell antibody (HBME-1) in both, whereas CD34 and bcl2 were negative. Solitary fibrous tumor was excluded. Therefore, pathological, ultrastructural, and immunohistochemical findings led us a diagnosis of DMM in each case. The Ki-67 labeling index (Ki-67 LI) of cases 1 and 2 was 25.5 and 15.5, respectively, both high, which suggested malignancy. Widespread immunohistological panels of malignant mesothelioma were not evaluated; Immunohistological markers commonly used for the diagnosis of malignant mesothelioma were not evaluated; however, the high ki-67 LI results and positive HBME-1 staining were helpful factors for the diagnoses of DMM.     

Immunoreactivity for p53 and mdm2 and the detection of p53 mutations in human malignant mesothelioma

Previous immunohistochemical studies on malignant mesothelioma with antibodies recognizing both the wild and the mutant types of the p53 protein have shown immunoreactivity in 25–70% of cases. This study was designed to determine whether there is immunoreactivity for p53 and mdm2 protein in malignant mesothelioma and to correlate p53 expression with the detection of mutations in p53 at DNA level. In 10 of 15 cases there was immunoreactivity for p53. In 6 of these cases immunoreactivity for mdm2 was also detected. In one p53-immunonegative case, a mutation of the p53 gene resulting in a stop codon was found. These results suggest that mdm2 might be involved in the inhibition of p53 in malignant mesothelioma. Also, these data suggest the existence of other proteins than mdm2 that may associate with p53.This work was supported by the Belgian Cancer Association (Vereniging voor Kankerbestrijding) and the Flemish Biotechnology Programme of the Ministry of Economy     

Expression of Wilms tumor-1 protein and CD 138 in malignant mesothelioma of the tunica vaginalis

Malignant mesothelioma (MM) of the tunica vaginalis is a very rare tumor which can be difficult to diagnose histologically. We report an 83-year-old patient with MM of tunica vaginalis of the left testis. To the best of our knowledge, this is the first reported case of MM of the tunica vaginalis expressing Wilms tumor-1 protein, CD138, the expression of which could help in confirming the histopathological diagnosis and in targeting therapy.