Problems in mesothelioma diagnosis

Comparison of Immunohistochemistry, Next-generation Sequencing and Fluorescence In Situ Hybridization for Detection of MTAP Loss in Pleural Mesothelioma

9p21 deletions involving MTAP/CDKN2A genes are detected in diffuse pleural mesotheliomas (DPM) but are absent in benign mesothelial proliferations. Loss of MTAP expression by immunohistochemistry (IHC) is well accepted as a surrogate for 9p21 deletion to support a diagnosis of DPM. Accurate interpretation can be critical in the diagnosis of DPM, but variations in antibody performance may impact interpretation. The objectives of this study were to compare the performance of MTAP monoclonal antibodies (mAbs) EPR6893 and 1813 and to compare MTAP expression by IHC with 9p21 copy number status in DPM. Cytoplasmic expression of MTAP IHC with mAbs EPR6893 (ab126770; Abcam) and 1813 (NBP2-75730, Novus Biologicals) was evaluated in 56 DPM (47 epithelioid, 7 biphasic, and 2 sarcomatoid) profiled by targeted next-generation sequencing. 9p21 Copy number status was assessed by Fraction and Allele-Specific Copy Number Estimates from Tumor Sequencing (FACETS) analysis and also by CDKN2A fluorescence in situ hybridization in discrepant cases when material was available. MTAP mAb 1813 showed stronger immunoreactivity, more specific staining, and no equivocal interpretations compared to mAb EPR6893 which showed equivocal staining in 19 (34%) of cases due to weak or heterogenous immunoreactivity, lack of definitive internal positive control, and/or nonspecific background staining. MTAP expression with mAb 1813 showed near perfect agreement with 9p21 copy number by combined FACETS/fluorescence in situ hybridization calls (κ = 0.85; 95% CI, 0.71-0.99; P < .001). MTAP IHC with mAb 1813 was 96% sensitive, 86% specific, and 93% accurate for 9p21 homozygous deletion. The findings of this study suggest that interpretation of MTAP IHC is improved with mAb 1813 because mAb EPR6893 was often limited by equivocal interpretations. We show that MTAP IHC and molecular assays are complementary in detecting 9p21 homozygous deletion. MTAP IHC may be particularly useful for low tumor purity samples and in low-resource settings.

An efficient context-aware approach for whole-slide image classification

Computational pathology for gigapixel whole-slide images (WSIs) at slide level is helpful in disease diagnosis and remains challenging. We propose a context-aware approach termed WSI inspection via transformer (WIT) for slide-level classification via holistically modeling dependencies among patches on WSI. WIT automatically learns feature representation of WSI by aggregating features of all image patches. We evaluate classification performance of WIT and state-of-the-art baseline method. WIT achieved an accuracy of 82.1% (95% CI, 80.7%-83.3%) in the detection of 32 cancer types on the TCGA dataset, 0.918 (0.910-0.925) in diagnosis of cancer on the CPTAC dataset, and 0.882 (0.87-0.890) in the diagnosis of prostate cancer from needle biopsy slide, outperforming the baseline by 31.6%, 5.4%, and 9.3%, respectively. WIT can pinpoint the WSI regions that are most influential for its decision. WIT represents a new paradigm for computational pathology, facilitating the development of digital pathology tools.

Systematic Review, Meta-Analysis and Bioinformatic Analysis of Biomarkers for Prognosis of Malignant Pleural Mesothelioma

In previous studies, non-invasive diagnostic biomarkers showed great benefit in the early-stage diagnosis of malignant pleural mesothelioma (MPM). However, the accuracy of different biomarkers was controversial. In this study, meta-analysis and bioinformatics analysis were conducted to compare the accuracy of the following three biomarkers and explore the relationship between the gene expression levels and MPM. A systematic search of meta-analysis was conducted using PubMed, EMBASE and Cochrane Library to identify relevant studies from the inception to March 2021. QUADAS-2 for Quality Assessment of Diagnostic Accuracy Studies was used to evaluate the quality of eligible studies. The meta-analysis was performed utilizing Stata 15.0 and Review Manager 5.4 software. The meta-analysis results showed that 31 studies that involved 8750 participants were included. The pooled sensitivity and specificity (SPE) were 0.90 (95% CI: 0.74, 0.97) and 0.91 (95% CI: 0.84, 0.95) for Fibulin-3, 0.66 (95% CI, 0.51–0.78) and 0.91 (95% CI, 0.82–0.96) for mesothelin (MSLN), 0.68 (95% CI: 0.63,0.73) and 0.86 (95% CI: 0.82,0.90) for soluble mesothelin-related peptides (SMRP), and 0.74 (95% CI, 0.66-0.80) and 0.89 (95% CI, 0.85–0.91) for MSLN + SMRP + Fibulin-3. Compared with the other two biomarkers, Fibulin-3 may be more appropriate to be one of the indicators for combined diagnosis. Bioinformatics analysis showed that the low expression level of the MSLN gene was significantly related to longer survival time and better prognosis of MPM patients. However, considering the limitation in the quality and sample size of the included research, further studies are required.

Prognosis of patients with malignant mesothelioma by expression of programmed cell death 1 ligand 1 and mesothelin in a contemporary cohort in Finland

OBJECTIVES

We aimed to describe mesothelin (MSLN) and programmed cell death 1 ligand 1 (PD-L1) tumour overexpression amongst patients with malignant mesothelioma (MM), and their associations with survival, amongst a cohort of patients with MM in Finland.

METHODS

Between 2004 and 2017, 91 adults with histologically confirmed MM were identified from the Auria Biobank in Finland and followed-up using linked data from electronic health records and national statistics. Biomarker content in tumour cell membranes was determined using automated Immunohistochemistry on histological sections. Stained tumour sections were scored for MSLN and PD-L1 intensity. Adjusted associations between MSLN/PD-L1 co-expression and mortality were evaluated by estimating hazard ratios (HRs) with 95% confidence intervals (CIs) using Cox regression.

RESULTS

Biomarker overexpression occurred in 52 patients for MSLN and 34 patients for PD-L1 and was associated with tumour histology and certain comorbidities. Fifteen per cent of patients had a tumour that overexpressed both biomarkers; r =-0.244, p-value: 0.02. Compared with MSLN+/PD-L1+ patients, HRs (95% CIs) for death were 4.18 (1.71-10.23) for MSLN-/PD-L1+ patients, 3.03 (1.35-6.77) for MSLN-/PD-L1- patients, and 2.13 (0.97-4.67) for MSLN+/PD-L1- patients.

CONCLUSIONS

Both MSLN and PD-L1 markers were independent prognostic indicators in patients with MM. Overexpression of MSLN was associated with longer survival; yet their combined expression gave a better indication of survival. The risk of death was four times higher amongst MSLN-/PD-L1+ patients than in MSLN+/PD-L1+ patients.

Diffuse pleural thickening and thoracic contraction: An indistinguishable case from malignant pleural mesothelioma

The differential diagnosis of reactive mesothelial hyperplasia and mesothelioma is difficult. We present a rare case of diffuse pleural thickening with thoracic contraction that was indistinguishable from mesothelioma. A 66-year-old woman with no history of asbestos exposure visited our hospital with a complaint of dyspnea. The clinical findings included circumferential pleural thickening on chest computed tomography image and a high concentration of hyaluronic acid in the pleural fluid. Pleural biopsies obtained by thoracoscopy under local anesthesia were pathologically consistent with mesothelioma, but the patient refused to take any kind of mesothelioma treatments. Four months later, she consented to a surgical pleural biopsy under general anesthesia to obtain larger tissue samples, which included typical proliferating polygonal cells positive for CAM5.2, calretinin, WT-1, D2-40, CK5/6, epithelial membrane antigen, and glucose transporter-1 and negative for carcinoembryonic antigen, BerEP4, and MOC31. The analysis was consistent with diagnosis of epithelioid mesothelioma. Fluorescence in situ hybridization, however, showed the presence of p16 gene, and the expression of BRCA1-associated protein-1 was detected by immunohistochemistry. Our final diagnosis was diffuse pleural thickening unrelated to asbestos exposure. Differential diagnosis of diffuse pleural thickening and malignant mesothelioma is thus difficult and routine immunohistochemical examinations are often insufficient for accurate diagnosis. Multiple diagnostic methods are required for correct diagnosis in a clinically marginal case.

Acute popliteal thrombus workup leads to discovery of primary peritoneal mesothelioma in the absence of any known asbestos exposure

A 75-year-old man presented to the emergency department with 1-day history of right lower limb pain and 3-month history of vague abdominal pain. In the emergency department a thrombus was discovered in the right popliteal artery. CT scan of the abdomen and pelvis revealed high-density material in the pelvis, multiple hypodensities on the liver, ascites with omental nodularity, and high-density material along the stomach wall. He underwent thrombectomy and was started on anticoagulation therapy. The core needle biopsy revealed primary omental mesothelioma. There was no history of any known asbestos exposure. He also had to undergo therapeutic paracentesis twice due to abdominal distension. Mesothelioma treatment of carboplatin and pemetrexed was started, and the patient is currently receiving this chemotherapy treatment regimen.

MicroRNA Signatures in Malignant Pleural Mesothelioma Effusions

Malignant pleural mesothelioma (MPM) is an incurable cancer of the pleura that can be difficult to diagnose. Biomarkers for an easier and/or earlier diagnosis are needed. Approximately 90% of MPM patients develop a pleural effusion (PE). PEs are ideal sources of biomarkers as the fluid would almost always require drainage for diagnostic and/or therapeutic reasons. However, differentiating MPM PE from PE caused by other diseases can be challenging. MicroRNAs are popular biomarkers given their stable expression in tissue and fluid. MicroRNAs have been analysed in PE cytology samples for the diagnosis of MPM but have not been measured in frozen/fresh PE. We hypothesise that microRNAs expressed in PE are biomarkers for MPM. TaqMan OpenArray was used to analyse over 700 microRNAs in PE cells and supernatants from 26 MPMs and 21 other PE-causing diseases. In PE cells, combining miR-143, miR-210, and miR-200c could differentiate MPM with an area under the curve (AUC) of 0.92. The three-microRNA signature could also discriminate MPM from a further 40 adenocarcinomas with an AUC of 0.9887. These results suggest that the expression of miR-143, miR-210, and miR-200c in PE cells might provide a signature for diagnosing MPM.

Pleural malignant mesothelioma versus pleuropulmonary synovial sarcoma: a clinicopathological study of 22 cases with molecular analysis and survival data

The aim of this study was to carry out a comparative analysis by transducin-like enhancer of split 1 (TLE1) immunohistochemistry and molecular analysis of SYT-SSX, for 16 pleural predominantly sarcomatoid mesotheliomas and six cases of pleuropulmonary synovial sarcoma (five pleural in distribution only, with one case of a predominantly subpleural upper lobe synovial sarcoma), all of which were solely or predominantly monophasic. Our comparison included survival and some clinical data. We consider that the following points emerged from this study.

Secreted and Tissue miRNAs as Diagnosis Biomarkers of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare but aggressive tumor that originates in the pleura, is diagnosed in advanced stages and has a poor prognosis. Accurate diagnosis of MPM is often difficult and complex, and the gold standard diagnosis test is based on qualitative analysis of markers in pleural tissue by immunohistochemical staining. Therefore, it is necessary to develop quantitative and non-subjective alternative diagnostic tools. MicroRNAs are non-coding RNAs that regulate essential cellular mechanisms at the post-transcriptional level. Recent evidence indicates that miRNA expression in tissue and body fluids is aberrant in various tumors, revealing miRNAs as promising diagnostic biomarkers. This review summarizes evidence regarding secreted and tissue miRNAs as biomarkers of MPM and the biological characteristics associated with their potential diagnostic value. In addition to studies regarding miRNAs with potential diagnostic value for MPM, studies that aimed to identify the miRNAs involved in molecular mechanisms associated with MPM development are described with an emphasis on relevant aspects of the experimental designs that may influence the accuracy, consistency and real diagnostic value of currently reported data.

Malignant Mesothelioma of the Pleura in Nonagenarian Patients

Aims and background

Malignant mesothelioma developing at very old ages is a rare event. The reasons for such late development were investigated.

Methods

A series of 811 malignant mesothelioma of the pleura, diagnosed at the Trieste and Monfalcone Hospitals, in northeastern Italy, in the period 1968–2008 were reviewed. Eight cases regarding patients aged 90 years or more were selected. In such cases, occupational histories were re-examined, and additional data could be obtained from the patients' relatives. Routine lung sections obtained at necropsy were examined for asbestos bodies. In 2 cases, asbestos bodies had been isolated after chemical digestion of lung tissue.

Results

The group included 7 men and one woman, aged between 90 and 93 years. All 8 patients had long-term histories of occupational exposure to asbestos, mostly in shipyards. Latency periods, elapsed between first exposure to asbestos and tumor manifestation, ranged between 64 and 75 years. Asbestos bodies were found on routine lung sections in 6 cases. Isolation of lung asbestos bodies showed 72, 000 bodies per gram of dried tissue in a90-year-old man, who had worked in the shipyards for 34 years, and 150 bodies per gram in a 93-year-old woman, who had worked in the shipyards for 23 years.

Conclusions

In this group of cases, the late development of mesothelioma can not be attributed to mild exposure to asbestos or to unusually late exposures. Very long latency periods even in people heavily exposed suggest an individual resistance to the oncogenic effects of asbestos.

E-cadherin expression is correlated with focal adhesion kinase inhibitor resistance in Merlin-negative malignant mesothelioma cells

Malignant mesothelioma (MM) is an aggressive tumor commonly caused by asbestos exposure after a long latency. Focal adhesion kinase (FAK) inhibitors inhibit the cell growth of Merlin-deficient MM cells; however, their clinical efficacy has not been clearly determined. The aim of this study was to evaluate the growth inhibitory effect of the FAK inhibitor VS-4718 on MM cell lines and identify biomarkers for its efficacy. Although most Merlin-deficient cell lines were sensitive to VS-4718 compared with control MeT-5A cells, a subset of these cell lines exhibited resistance to this drug. Microarray and qRT-PCR analyses using RNA isolated from Merlin-deficient MM cell lines revealed a significant correlation between E-cadherin mRNA levels and VS-4718 resistance. Merlin- and E-cadherin-negative Y-MESO-22 cells underwent apoptosis upon treatment with a low concentration of VS-4718, whereas Merlin-negative, E-cadherin-positive Y-MESO-9 cells did not undergo VS-4718-induced apoptosis. Furthermore, E-cadherin knockdown in Merlin-negative MM cells significantly sensitized cells to VS-4718 and induced apoptotic cell death upon VS-4718 treatment. Together, our results suggest that E-cadherin serves as a predictive biomarker for molecular target therapy with FAK inhibitors for patients with mesothelioma and that its expression endows MM cells with resistance to FAK inhibitors.

Mortalidad por mesotelioma en Argentina, 1980-2013

Se estimó la tasa de mortalidad por mesotelioma y su distribución sociodemográfica y temporal en Argentina para el período 1980-2013 con datos del Sistema de Estadísticas Vitales del Ministerio de Salud de la Nación. Se encontraron 3.259 defunciones por mesotelioma, lo que resulta en una tasa de mortalidad estandarizada por edad de 3,1/1.000.000 en 1980 y de 5,7/1.000.000 en 2013, con un aumento promedio del 84,1% en 34 años. El incremento de la tendencia fue más claro a partir de 1997. En todos los años, la tasa de mortalidad fue mayor en hombres que en mujeres. Los resultados sugieren antecedentes de exposición al asbesto en el pasado. Aparentemente, la exposición predominante fue la ocupacional, más común entre los hombres que concentraron los casos. Se recomiendan acciones dirigidas a hacer más efectiva la prohibición ya en vigor y la vigilancia en salud orientada a los ambientes de trabajo, trabajadores previamente expuestos y la población en general.

Improving the Accuracy of Mesothelioma Diagnosis in China

INTRODUCTION

In the Western world, malignant mesothelioma (MM) is most prevalent in the pleura of older males who have been professionally exposed to asbestos. Information about MM from rapidly industrializing countries such as China is minimal. There is concern that a proportion of MM diagnoses in China may be incorrect because most Chinese physicians do not have experience diagnosing this rare cancer. We recently reported an unusually high incidence of peritoneal MM among eastern Chinese female patients. Here, we review the accuracy of MM diagnoses in China and provide suggestions to improve the accuracy of diagnosis.

METHODS

We reviewed 92 pathological diagnosis of MM in 2002-2015 from two reference centers in the province of Zhejiang in eastern China. We performed a large set of immunohistochemistry analyses to increase the reliability of the diagnosis.

RESULTS

We confirmed the MM diagnosis in 12 of 34 of the pleural tumors (35.3%), in 38 of 56 of the peritoneal tumors (67.9%), and in two of two of the MMs of the tunica vaginalis (100%). MMs were characterized by tumor cells showing nuclear Wilms tumor 1 and calretinin staining and by strong membranous staining for cytokeratin CAM5.2. The results of staining for the epithelial markers carcinoembryonic antigen, thyroid transcription factor-1, MOC31, BerEP4, p63, p40, paired box 8, ER and PR were negative. BRCA1 associated protein 1 nuclear staining was lost in percentages similar to what has been reported for samples from Western countries.

CONCLUSIONS

Our findings suggest that MM-especially in its pleural localization-is often misdiagnosed in eastern China. Identifying pitfalls and possible solutions in the pathological diagnosis of MM will affect both the standard of care and research in China.

DNA copy number gains in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor with an extremely poor prognosis. The incidence of MPM is increasing as a result of widespread exposure to asbestos. The molecular pathogenesis of MPM remains unclear. The present study analyzed the frequency of various genomic copy number gains (CNGs) in MPM using reverse transcription-quantitative polymerase chain reaction. A total of 83 primary MPMs and 53 primary lung adenocarcinomas were analyzed to compare the CNGs of EGFR, KRAS, MET, FGFR1 and SOX2. In MPM, the CNGs of EGFR, KRAS, MET, FGFR1 and SOX2 were detected in 12 (14.5%), 8 (9.6%), 5 (6.0%), 4 (4.8%) and 1 (1.2%) of the samples, respectively. In lung adenocarcinomas, the CNGs of EGFR, KRAS, MET, FGFR1 and SOX2 were detected in 21 (39.6%), 12 (22.6%), 5 (9.4%), 10 (18.9%) and 0 (0.0%) of the samples, respectively. The CNGs of EGFR, KRAS and FGFR1 were significantly less frequent in the MPMs compared with the lung adenocarcinomas (P=0.0018, 0.048 and 0.018, respectively). Overall, the MPMs exhibited these CNGs less frequently compared with the lung adenocarcinomas (P=0.0002). The differences in CNGs between the two tumor types suggested that they are genetically different.

Detection of malignant mesothelioma using nuclear structure of mesothelial cells in effusion cytology specimens

Mesothelioma is a form of cancer generally caused from previous exposure to asbestos. Although it was considered a rare neoplasm in the past, its incidence is increasing worldwide due to extensive use of asbestos. In the current practice of medicine, the gold standard for diagnosing mesothelioma is through a pleural biopsy with subsequent histologic examination of the tissue. The diagnostic tissue should demonstrate the invasion by the tumor and is obtained through thoracoscopy or open thoracotomy, both being highly invasive surgical operations. On the other hand, thoracocentesis, which is removal of effusion fluid from the pleural space, is a far less invasive procedure that can provide material for cytological examination. In this study, we aim at detecting and classifying malignant mesothelioma based on the nuclear chromatin distribution from digital images of mesothelial cells in effusion cytology specimens. Accordingly, a computerized method is developed to determine whether a set of nuclei belonging to a patient is benign or malignant. The quantification of chromatin distribution is performed by using the optimal transport-based linear embedding for segmented nuclei in combination with the modified Fisher discriminant analysis. Classification is then performed through a k-nearest neighborhood approach and a basic voting strategy. Our experiments on 34 different human cases result in 100% accurate predictions computed with blind cross validation. Experimental comparisons also show that the new method can significantly outperform standard numerical feature-type methods in terms of agreement with the clinical diagnosis gold standard. According to our results, we conclude that nuclear structure of mesothelial cells alone may contain enough information to separate malignant mesothelioma from benign mesothelial proliferations.

Pleural fluid mesothelin as an adjunct to the diagnosis of pleural malignant mesothelioma

Rationale. The diagnosis of pleural malignant mesothelioma (MM) by effusion cytology may be difficult and is currently controversial. Effusion mesothelin levels are increased in patients with MM but the clinical role of this test is uncertain. Objectives. To determine the clinical value of measuring mesothelin levels in pleural effusion supernatant to aid diagnosis of MM. Methods and Measurements. Pleural effusion samples were collected prospectively from 1331 consecutive patients. Mesothelin levels were determined by commercial ELISA in effusions and their relationship to concurrent pathology reporting and final clinical diagnosis was determined. Results. 2156 pleural effusion samples from 1331 individuals were analysed. The final clinical diagnosis was 183 MM, 436 non-MM malignancy, and 712 nonmalignant effusions. Effusion mesothelin had a sensitivity of 67% for MM at 95% specificity. Mesothelin was elevated in over 47% of MM cases in effusions obtained before definitive diagnosis of MM was established. In the setting of inconclusive effusion cytology, effusion mesothelin had a positive predictive value of 79% for MM and 94% for malignancy. Conclusions. A mesothelin-positive pleural effusion, irrespective of the identification of malignant cells, indicates the likely presence of malignancy and adds weight to the clinical rationale for further investigation to establish a malignant diagnosis.

Comparison of fibulin-3 and mesothelin as markers in malignant mesothelioma

BACKGROUND

Pleural malignant mesothelioma (MM) is a deadly tumour predominantly associated with asbestos exposure. A reliable diagnostic and prognostic marker for MM will significantly enhance clinical care and is an area of intense research. Soluble mesothelin is the most studied and an FDA-approved biomarker for MM. A recent report showed promising results using fibulin-3 as a new diagnostic marker. The aim of this study was to compare the utility of fibulin-3 versus mesothelin, singly or in combination.

METHODS

Fibulin-3 and soluble mesothelin were determined by ELISA in the plasma and pleural fluid of 153 patients presenting with a pleural effusion including 82 with MM, 36 with non-MM malignant effusions and 35 with benign effusions. Biomarker concentrations were determined in the plasma of an additional 49 cases with benign asbestos-related disease.

RESULTS

Mesothelin provides better diagnostic accuracy than fibulin-3 for MM whether measured in plasma or pleural effusion: area under the curve (AUC) for plasma was 0.822 (95% CI 0.76 to 0.87) compared with 0.671 (0.61 to 0.73), respectively, and for pleural fluid AUC was 0.815 (0.74 to 0.87) compared with 0.588 (0.51 to 0.67), respectively. Effusion fibulin-3 was an independent significant prognostic factor for survival in MM patients; HR 2.08 (1.14 to 3.82), p=0.017. MM patients with effusion fibulin-3 levels below the median survived significantly longer than those with levels above the median (14.1 vs 7.9 months, p=0.012). Mesothelin and neutrophil to lymphocyte ratio were not significant prognostic markers.

CONCLUSIONS

Soluble mesothelin is a superior diagnostic biomarker for MM compared with fibulin-3, whereas fibulin-3 provides superior prognostic information compared with mesothelin.

Pleural mesothelioma: an institutional experience of 66 cases

Background

Malignant mesothelioma of the pleura is an aggressive tumor known to be associated with asbestos. Histological diagnosis of mesothelioma is challenging and is usually aided by immunohistochemical markers.

Methods

During an 18-year period (1995-2012), 66 patients with pleural mesothelioma were diagnosed at the Samsung Medical Center in Seoul. We reviewed hematoxylin and eosin and immunohistochemical slides of pleural mesothelioma and evaluated their pathological and clinical features.

Results

The male-to-female ratio was 1.75:1, and age of patients ranged from 28 to 80 years with an average age of 56.84 years. Twenty-two out of 66 patients underwent curative pneumonectomy. Follow-up data was available in 60 patients (90.9%), and 50 of them (83.3%) died from the disease. The average overall survival was 15.39 months. Histologically, the epithelioid type was the most common, followed by the sarcomatoid and the biphasic types. Epidemiologic information was not available in most cases, and only one patient was confirmed to have a history of asbestos exposure.

Conclusions

Malignant mesothelioma of the pleura is a fatal tumor, and the therapeutic benefit of pneumonectomy remains unproven. The combination of calretinin, Wilms tumor 1, HMBE-1, and thyroid transcription factor-1 may provide high diagnostic accuracy in diagnosing mesothelioma.

Malignant pleural mesothelioma: a single-center experience in Turkey

BACKGROUND

Malignant pleural mesothelioma is a rare lethal malignancy caused by asbestos exposure. It is more frequently seen in certain regions in Turkey. In this retrospective study, we aimed to analyse demographic, clinical, and pathological data and treatment-related features in 54 patients.

MATERIAL AND METHODS

The study included 54 patients diagnosed with malignant mesothelioma that were followed and treated.

RESULT

Of the 54 patients, 34 (55.6%) were male. The median age in men and women were 60.3 (38.2-77.2) and 65.8 (37.7-77.5) years, respectively. In 35 (64.8%), exposure to asbestosis was present. Epithelial type was found in 27 (50.0%), followed by mixed type in 7 (13.0%) patients, and in 20 (37.0%) patients the subtype could not be determined. The disease was staged as IV in 37 (68.5%) patients. In 28 patients (51.9%), it was right-sided and in 1 (1.9%) it was bilateral. The most frequent metastatic sites (in decreasing order) were lungs, mediastinum, diaphragm, liver, and thoracal wall. Of the 54 patients, 36 (66.6%) received 1st-line chemotherapy and 20 (37%) 2nd-line chemotherapy. Eighteen patients (33.3%) received radiotherapy; 11 (20.3%) with palliative intention and 7 (12.9%) with curative intention. Median overall survival (OS) was 12.03 months (95% CI 7.2-16.8). OS was not affected by sex (p=0.32), smoking history (p=0.51), alcohol consumption (p=0.36), family history (p=0.67), pleural effusion presence (p=0.80), operation (p=0.14), clinical stage (p=0.072), symptom at presentation (p=0.66), having mixed type histology (p=0.079), asbestos exposure (p=0.06), and type of 1st-line chemotherapy (p=0.161). On the contrary, it may be positively affected by good ECOG PS (0-1) (p<0.01), age below 65 (p=0.03), left-sided disease (p=0.01), receiving chemotherapy (p<0.01), having unilateral pleural effusion (p=0.018), and type of 2nd-line chemotherapy (p=0.025).

CONCLUSIONS

OS of our patients was better than that found in the literature, seeming to be positively affected by early stages, better ECOG PS, age below 65 years, left side involvement, and having second-line chemotherapy with cisplatin-gemcitabine or 3M. Overall treatment success seems to be comparable to what is currently expected.

[Regional treatment of malignant pleural mesothelioma: results from the tumor centre Regensburg]

INTRODUCTION

Malignant pleural mesothelioma (MPM) is an aggressive, malignant tumor of the pleural surface and is strongly associated with asbestos exposure. Incidence of MPM will reach its peak over the coming years. Most patients present with advanced tumor stages and therefore surgical options are limited.

PATIENTS AND METHODS

Retrospective analysis of all patients with MPM reported to the tumor centre Regensburg between January 1998 and August 2011.

RESULTS

A total of 118 patients (85 % male) with cytologically or histologically confirmed MPM were reported. The mean age at diagnosis was 67 years (range 45-84 years) and 65 % of patients had a history of asbestos exposure. The incidence of MPM at the tumor centre Regensburg was 0.8/100,000 inhabitants with obvious regional differences depending on asbestos exposure. Staging was completed in 81 patients (67 %): stage I 9 %, stage II 22 %, stage III 23 % and stage IV 46 %. Of the patients 87 (74 %) underwent at least one surgical procedure: diagnostic thoracoscopy with biopsy (n = 37, 43 %), debulking surgery or talcum pleurodesis (n = 33, 38 %) and potentially curative resection (n = 17, 19 %). After a mean follow-up of 20 months the overall median survival was 14 months (1 year survival rate 62 %, 3 year survival rate 15 %). Patients had a significantly better median survival of 18 months after curative resection.

CONCLUSIONS

The distribution of MPM varies according to regional and industrial asbestos exposure. Screening and diagnostics should concentrate on locations with higher incidence of MPM to facilitate surgical therapy in a multimodal treatment regime.

Two cases of malignant peritoneal mesothelioma without asbestos exposure: cytologic and immunohistochemical features

Approximately half a century has passed since asbestos was first reported to be the main cause of malignant mesothelioma; yet the incidence of this disease continues to increase worldwide. Twenty percent of cases occur without prior asbestos exposure, and in these patients, malignant peritoneal mesothelioma is more common than malignant pleural mesothelioma. Here, we report the cytomorphologic and immunohistochemical features of 2 cases of malignant peritoneal mesothelioma where there was no history of asbestos exposure. Ascitic cytology showed that most cells were isolated and that clusters were rarely observed, but the findings were consistent with malignant mesothelioma in both cases. Immunohistochemical analysis for epithelial membrane antigen, calretinin, vimentin, β-catenin, melan-A, glucose transporter-1, cytokeratin CAM5.2, Wilms tumor antigen-1, D2-40, CD146, progesterone receptor, estrogen receptor, and cytokeratin 5/6 was indicative of malignant mesothelioma. In malignant mesothelioma without prior asbestos exposure, the etiology and prognostic significance is still unclear. Further study is needed to clarify this point.

The diagnostic value of immunohistochemically detected methylthioadenosine phosphorylase deficiency in malignant pleural mesotheliomas

AIMS

  Malignant pleural mesothelioma (MPM) often causes diagnostic difficulties for pathologists. We assessed whether loss of methylthioadenosine phosphorylase (MTAP), a key enzyme in the intracellular recycling of adenosine triphosphate (ATP) often deleted in MPM, could be detected with immunohistochemistry (IHC) and used as a diagnostic marker for MPM.

METHODS AND RESULTS

  We used IHC to detect MTAP in a cohort of 99 MPMs and 39 reactive mesothelial proliferations (RP) (reactive mesothelial hyperplasia n = 33, reactive pleural fibrosis n = 6). MTAP staining was assessed by an H score. The median H score of the RP cohort was set as a reference point. Cases with H scores below this reference point were considered to have decreased MTAP expression. We found that 64 of 99 (65%) of the investigated MPMs had decreased MTAP expression, while this was only true for nine of 39 (23%) of the RPs (P = 0.001). We further evaluated MTAP expression in a cohort of coagulated pleural effusions from 14 patients with MPM and 20 patients with RP by using a double-staining technique with Wilms tumour 1 (WT1) as a mesothelial marker. In these samples, decreased MTAP expression diagnosed MPM with a sensitivity of 71% and a specificity of 90%.

CONCLUSIONS

  Decreased MTAP expression could potentially be useful in combination with other markers in the diagnosis of MPM.

Pathological and molecular biological approaches to early mesothelioma

Malignant mesothelioma is an asbestos-related malignancy that arises primarily from mesothelial cells on the serosal surfaces of the pleural, peritoneal, and pericardial cavities. Malignant pleural mesothelioma (MPM) is most common, and its incidence is dramatically increasing worldwide as a result of widespread use of asbestos. Morphological discrimination between MPM and reactive mesothelial hyperplasia is difficult, and the most reliable pathological criterion for malignancy is mesothelial proliferation invading deeply into subpleural adipose tissues. To establish radical cure of MPM, it is crucial to find early-stage MPM of epithelial type, in which mesothelial proliferation is localized on the serosal surface of parietal pleura or limited within the submesothelial fibrous tissues of parietal pleura. The initial clinical presentation for patients with MPM is frequently dyspnea and/or chest pain due to large pleural effusion, and cytological analysis of pleural effusions is valuable to find patients with early-stage MPM of epithelial type. Recently, cytological features of MPM in pleural effusion, molecular markers for MPM, and genetic alternations of MPM have been reported. In this review, we discuss major issues on pathological and molecular biological approaches for diagnosis of early-stage MPM of epithelial type.

Pathohistological diagnosis and differential diagnosis

Malignant mesothelioma is a rare aggressive tumour arising from mesothelial cells of the pleural and peritoneal cavity including pericardium and tunica vaginalis testis. Malignant mesothelioma occurs predominantly in men (>90%). Asbestos exposure is the best known and evaluated risk factor with a long latency period between exposure and onset of malignant mesothelioma ranging from 15 to 60 years. Exposure to erionite leads to higher incidences of mesothelioma and play an important role in environmental exposure (Turkey). Other possible risk factors are radiation, recurrent pleuritis/peritonitis and simian virus 40 (SV 40).Malignant pleural mesothelioma is most common, whereas malignant peritoneal mesothelioma accounts only for 6-10%. Infrequent sites of origin are the pericardium and tunica vaginalis in 1-2%.Malignant mesothelioma shows either diffuse growth pattern or occurs as a localised tumour mass. Diffuse type represents an aggressive tumour with poor prognosis and is incurable in most cases.According to the WHO classification, three histological subtypes are distinguished: epithelioid, sarcomatoid and biphasic malignant mesothelioma.Rare variants are desmoplastic type, a subtype of sarcomatoid mesothelioma, undifferentiated type and deciduoid type. Epithelioid type is the most frequent one, but biphasic malignant mesothelioma occurs in 30%. Pure sarcomatoid or biphasic type is seen less frequently in malignant peritoneal mesothelioma than in its pleural counterpart.Well-differentiated papillary mesothelioma is a generally non-invasive mesothelioma with low malignant potential that arises mostly in females in the peritoneal cavity. Histological type is an important prognostic marker. Longest survival is seen in patients with epithelioid malignant mesothelioma. Sarcomatoid subtype has the worst prognosis.Malignant mesothelioma shows macroscopical and microscopical similarities to benign lesions and other malignancies. Therefore, reactive mesothelial proliferations on the one hand and secondary tumours resembling mesothelial cells as well as benign or rare mesothelial tumours on the other hand have to be distinguished. Additional immunohistochemistry is essential in histopathological assessment using a marker panel of antibodies.

Downregulated microRNAs in the differential diagnosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rapidly fatal disease whose diagnosis, particularly through less invasive techniques such as analysis of pleural effusion, can be challenging. Currently, a commercially available diagnostic test based on microRNA (miRNA) expression patterns is purported to distinguish between mesothelioma and lung adenocarcinoma. Yet, the biological basis of this technology has not been reported in the literature, and little research has been aimed at determining how differential miRNA expression contributes to the differences in pathogenesis between these diseases, both of which can be caused by asbestos exposure. We sought to illuminate the molecular differences between mesothelioma and lung adenocarcinoma by using miRNA microarrays to identify patterns in the most differentially expressed miRNAs. From this, we identified a panel of miRNAs, including members of the miR-200 gene family, that were all downregulated in MPM compared to lung adenocarcinoma. Using the more sensitive detection method of quantitative RT-PCR on an independent series of tumors, we validated the specificity of these alterations in 100 MPMs and 32 lung adenocarcinomas. Statistical analysis reveals that these miRNAs exceed the current recommendations for biomarkers and could greatly aid in the differential diagnosis. Further examination led us to predict that they act as redundant regulators of wnt signaling and suggests a role for this pathway in tumor progression. This research points to novel approaches using miRNAs whose decreased expression is unique to mesothelioma as potentially suitable for rapid diagnosis and reveals prospective new targets for the treatment of this deadly disease.

Expert opinions of the first italian consensus conference on the management of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a very important public health issue. A large amount of data indicates a relationship between mesothelioma and asbestos exposure. The incidence has both considerably and constantly increased over the past 2 decades in the industrialized countries and is expected to peak in 2010-2020. In Italy, a standardized-rate incidence in 2002 among men was 2.98 per 100,000 and 0.98 per 100,000 among women, with wide differences from one region to another. Stage diagnosis and definition may be difficult. Management of patients with MPM remains complex, so an optimal treatment strategy has not yet been clearly defined. The First Italian Consensus Conference on Malignant Pleural Mesothelioma was held Bologna (Italy) in May 20, 2008. The Consensus Conference was given the patronage of the Italian scientific societies AIOM, AIRO, AIPO, SIC, SICO, SICT, SIAPEC-IAP, AIOT, GOAM, and GIME. This Consensus did not answer all of the unresolved questions in MPM management, but the Expert Opinions have nonetheless provided recommendations, presented in this report, on MPM management for clinicians and patients.

Establishment of a cell line from a Japanese patient useful for generating an in vivo model of malignant pleural mesothelioma

Malignant pleural mesothelioma is a refractory tumor with increasing incidence. In the present study, we established six mesothelioma cell lines possessing two allele deletions of the p16(INK4A) gene and one allele deletion of the neurofibromatosis type 2 gene, MM16, MM21, MM26, MM35, MM46 and MM56, from pleural effusion fluids or surgically resected tumors of Japanese patients. MM21, MM26 and MM46 cells failed to develop tumors in BALB/c-nude mice following subcutaneous inoculation. MM16 and MM35 cells slowly generated tumors at the site of subcutaneous inoculation in BALB/c-nude mice, but lost the expression of mesothelioma-related markers such as calretinin, D2-40 and Wilms' tumor 1 in the subcutaneous tumors. On the other hand, MM56 cells rapidly generated tumors with the expression of calretinin and D2-40 in BALB/c-nude mice following subcutaneous inoculation. In addition, orthotopic implantation of MM56 cells into BALB/c-nude mice developed diffusely growing thoracic tumors by 3 weeks after implantation. Pleural effusions were observed in these mice 4 weeks after implantation. Thoracic tumors invaded aggressively into the chest wall 5 weeks after implantation and often metastasized into the lung, rib, peritoneum and pericardial cavity. On the pleural surface, MM56 cells were growing as single or multiple cell layers with the reactive mesothelium of recipient mice. These results indicate that MM56 cells can behave in a manner characteristic of human malignant pleural mesothelioma in the thoracic cavity of BALB/c-nude mice. The in vivo model using MM56 cells may be useful for studying the biological behavior of malignant pleural mesothelioma and developing its diagnostic and therapeutic strategies.

Predominantly fibrous malignant mesothelioma in a cat

Malignant mesotheliomas are rare tumours in domestic cats. They occur within the abdominal or thoracic cavity and are regularly associated with pleural or peritoneal effusions. The histopathological diagnosis can be quite challenging, as these neoplasms may resemble other epithelial or mesenchymal neoplasms. However, differentiation can be achieved by immunohistochemistry in most cases. Here we describe the rare case of a malignant mesothelioma of the fibrous subtype in the thoracic cavity of a cat and discuss differential diagnoses and treatment options for this tumor type.

Diagnostic performance of soluble mesothelin and megakaryocyte potentiating factor in mesothelioma

RATIONALE

Soluble mesothelin (SM) is currently the reference serum biomarker of malignant pleural mesothelioma (MPM). Megakaryocyte potentiating factor (MPF), which originates from the same precursor protein, is potentially more sensitive, yet lacks validation.

OBJECTIVES

To analyze the diagnostic performance of MPF as an MPM biomarker and compare this performance with SM.

METHODS

A total of 507 participants were enrolled in six cohorts: healthy control subjects (n = 101), healthy asbestos-exposed individuals (n = 89), and patients with benign asbestos-related disease (n = 123), benign respiratory disease (n = 46), lung cancer (n = 63), and MPM (n = 85). Sera were analyzed for SM and MPF levels using the Mesomark and Human MPF ELISA kit, respectively.

MEASUREMENTS AND MAIN RESULTS

SM and MPF levels differed significantly between patients with MPM and participants from each other cohort (P < 0.001). Receiver operating characteristics curve analysis did not reveal a significant difference between both markers in area under curve (AUC) for distinguishing MPM from all cohorts jointly (SM = 0.871, MPF = 0.849; P = 0.28). At 95% specificity, SM and MPF had a sensitivity of 64% (cutoff = 2.00 nmol/L) and 68% (cutoff = 12.38 ng/ml), respectively. Combining both markers did not improve the diagnostic performance.

CONCLUSIONS

In this prospective multicenter study, MPF is validated as a highly performant MPM biomarker. The similar AUC values of SM and MPF, together with the limited difference in sensitivity, show that both serum biomarkers have an equivalent diagnostic performance.

CDKN2A, NF2, and JUN are dysregulated among other genes by miRNAs in malignant mesothelioma -A miRNA microarray analysis

Malignant mesothelioma (MM) is an aggressive cancer arising from mesothelial cells, mainly due to former asbestos exposure. Little is known about the microRNA (miRNA) expression of MM. miRNAs are small noncoding RNAs, which play an essential role in the regulation of gene expression. This study was carried out to analyze the miRNA expression profile of 17 MM samples using miRNA microarray. The analysis distinguished the overall miRNA expression profiles of tumor tissue and normal mesothelium. Differentially expressed miRNAs were found in tumor samples compared with normal sample. Twelve of them, let-7b*, miR-1228*, miR-195*, miR-30b*, miR-32*, miR-345, miR-483-3p, miR-584, miR-595, miR-615-3p, and miR-885-3p, were highly expressed whereas the remaining nine, let-7e*, miR-144*, miR-203, miR-340*, miR-34a*, miR-423, miR-582, miR-7-1*, and miR-9, were unexpressed or had severely reduced expression levels. Target genes for these miRNAs include the most frequently affected genes in MM such as CDKN2A, NF2, JUN, HGF, and PDGFA. Many of the miRNAs were located in chromosomal areas known to be deleted or gained in MM such as 8q24, 1p36, and 14q32. Furthermore, we could identify specific miRNAs for each histopathological subtype of MM. Regarding risk factors such as smoking status and asbestos exposure, significantly differentially expressed miRNAs were identified in smokers versus nonsmokers (miR-379, miR-301a, miR-299-3p, miR-455-3p, and miR-127-3p), but not in asbestos-exposed patients versus nonexposed ones. This could be related to the method of assessment of asbestos exposure as asbestos remains to be the main contributor to the development of MM.

Malignant mesothelioma of the greater omentum mimicking omental infarction: A case report

Mesothelioma develops most commonly in the pleura, and less frequently in the peritoneum. Usually, it manifests as diffuse peritoneal thickening and multiple nodules, and rarely as a solitary mass. We report a rare case of primary malignant mesothelioma of the greater omentum, which mimicked omental infarct. A 54-year-old Korean man was admitted because of severe abdominal pain of sudden onset. A tender mass with indistinct margins was palpated in the upper abdomen. Abdominal ultrasound and computed tomography showed an ill-defined mass in the greater omentum and little ascites in the peri-hepatic space, and neutrophil-dominant exudates were documented on paracentesis. Intravenous antibiotics and analgesics were given for omental infarction with superimposed infection, which resulted in symptomatic improvement. The imaging studies after a week revealed a growing mass and ascites. Laparoscopic surgery was performed and an 8 cm × 3.3 cm greater omental mass was found, with multiple small nodules on the peritoneum, diaphragm, and pelvic cavity wall. Histological examination showed proliferating malignant epithelioid cells that stained strongly for calretinin, which was compatible with malignant mesothelioma. We recommend that primary omental mesothelioma should be included in the differential diagnosis of patients with omental infarction, despite its rarity.

Malignant pleural mesothelioma in Italy

This study reviews a series of 811 malignant pleural mesothelioma cases, diagnosed at hospitals in Trieste and Monfalcone districts of north eastern Italy, a narrow coastal strip with a population of about three lakh, in the period 1968-2008. The diagnosis was based on histological examination in 801 cases, and cytological findings in 10. Necropsy was performed in 610 cases. Occupational histories were obtained directly from the patients or their relatives through personal or telephone interviews. Routine lung sections were examined for asbestos bodies in 500 cases. In 143 cases asbestos bodies were isolated and counted by chemical digestion of the lung tissue using the Smith-Naylor method. The series included 717 men and 94 women aged between 32 and 93 years (mean 69.2 years). Detailed occupational data was obtained for 732 cases.The majority of patients had marine jobs - shipbuilding (449 cases), maritime trades (56 cases), and port activities (39 cases). The nature of work of other patients included a variety of occupations, with non-shipbuilding industries being the most common. Thirty-four women cleaned the work clothes of family members occupationally exposed and hence had a history of asbestos exposure at home. Most of the patients had their first exposure to asbestos before 1960. The latency period ranged between 13 and 73 years (mean 48.2). Latency period among insulators and dock workers were shorter than other categories. Asbestos bodies were detected on routine lung sections in 343 cases (68.6%). Lung asbestos body burdens after isolation ranged between two to 10 millions bodies per gram of dried tissue. Despite some limitations in the use of asbestos in this area since the 1970s, the incidence of tumor remained high during the last years.