Applications and limitations of immunohistochemistry in the diagnosis of malignant mesothelioma

Pleural Mesothelioma: Current Practice and Approach

Pleural mesotheliomas represent one of the most common diagnostic challenges in thoracic pathology. The diagnosis of pleural mesothelioma weighs heavily on clinical and radiologic information. In addition, in the past, before the era of immunohistochemistry, the diagnosis was aided with the use of special histochemical stains-PAS, D-PAS, and mucicarmine, which now very much have been replaced by immunohistochemical stains. In the era of immunohistochemistry, a combination of carcinomatous epitopes and positive mesothelioma markers has become paramount in the diagnosis of mesothelioma, and more recently the use of molecular techniques has become another ancillary tool in supporting such a diagnosis. At the same time, the treatment and clinical outcome of these patients may in some measure be determined by the histopathological features of the tumor and one that also over the years has changed from a palliative type to surgery, chemotherapy, radiotherapy, or a combination of these types. The histopathological growth patterns of mesothelioma are also wide, and in some cases may mimic other tumors that may be primary or metastatic to the pleura. Therefore, the assessment of the diagnosis of mesothelioma is one that requires a global view of the different factors including clinical, radiologic, pathologic-including immunohistochemistry and molecular diagnosis.

When the Diagnosis of Mesothelioma Challenges Textbooks and Guidelines

The diagnosis of malignant mesothelioma (MPM) does not pose difficulties when presenting with usual clinico-radiologic features and morphology. Pathology textbooks and national/international guidelines generally describe the findings of classic MPM, underlining common clinical presentation, the gold standard of sampling techniques, usual morphologic variants, immunohistochemical results of several positive and negative primary antibodies in the differential diagnosis, and the role of novel molecular markers. Nevertheless, MPM often does not follow the golden rules in routine practice, while the literature generally does not sufficiently emphasize unusual features of its manifestation. This gap may potentially create problems for patients in sustaining a difficult diagnosis of MPM in clinical practice and during legal disputes. Indeed, the guidelines accidentally tend to favor the job of lawyers and pathologists defending asbestos-producing industries against patients suffering from MPM characterized by uncommon features. The current review is aimed at underlining the wide spectrum of clinical and radiological presentation of MPM, the possibility to consistently use cytology for diagnostic intent, the aberrant immunohistochemical expression using so-called specific negative and positive primary antibodies, and finally proposing some alternative and more unbiased approaches to the diagnosis of MPM.

Sarcomatoid Mesothelioma: A Clinicopathological and Immunohistochemical Study of 64 Cases

Sixty-four cases of sarcomatoid pleural mesothelioma represent the basis of this study. The patients are 51 men and 13 women between the ages of 42 and 79 years, who presented with symptoms of chest pain, cough, and weight loss. Diagnostic imaging showed the presence of diffuse pleural thickening with encasement of the lung parenchyma in all the cases. All patients had surgical resection via extrapleural pneumonectomy. By immunohistochemistry, all cases were positive for cytokeratin AE1/AE3; however, reactivity with other markers including keratin 5/6, calretinin, and D2-40 was seen in different proportions, whereas a few cases showed positive staining for GATA3, WT1, and p40. All tumors were negative for carcinomatous epitopes (carcinoembryonic antigen, CD15, and TTF1). Our findings show that even though the use of immunohistochemical stains plays an important role in the final interpretation, the best results are accomplished by a global interpretation of clinical, radiographical, and immunohistochemical findings. It is also important to highlight that it does not seem to be a single immunohistochemical stain that is pathognomonic of sarcomatoid mesothelioma and that some other stains that are commonly used for other tumors may also show positive staining in a small percentage of sarcomatoid mesotheliomas.

LOX family and ZFPM2 as novel diagnostic biomarkers for malignant pleural mesothelioma

Background

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer that develops in the pleural and outer layer of tissues surrounding the lungs. MPM is primarily caused by occupational exposure to asbestos and results in a poor prognosis. Effective therapeutics as well as early diagnostics for the MPM are still lacking. To identify potential diagnostic biomarkers for MPM, we performed bioinformatics analysis of public database.

Methods

Utilizing databases from Cancer Cell Line Encyclopedia (CCLE) and Gene Expression Omnibus (GEO), we identified several potential candidates that could act as MPM biomarkers. We carried out additional molecular analyses of these potential markers using MPM patient tissue samples via quantitative polymerase chain reaction.

Results

We identified Lysyl oxidase (LOX), Lysyl oxidase homologs 1&2 (LOXL1& LOXL2) Zinc Finger Protein, FOG Family Member 2 (ZFPM2) as potential diagnostic biomarkers for MPM. In this study, we found that the LOX family and ZFPM2 showed comparable diagnostic ability to Fibulin-3 or mesothelin (MSLN) and would be better potential biomarkers than Sulfatase 1 (SULF1), Thrombospondin 2 (THBS2) and Cadherin 11 (CDH11).

Conclusions

LOX family and ZPFM2 were identified as novel MPM diagnostic biomarkers which could strengthen MPM clinical diagnostic capabilities.

Omics-based molecular techniques in oral pathology centred cancer: prospect and challenges in Africa

BACKGROUND

The completion of the human genome project and the accomplished milestones in the human proteome project; as well as the progress made so far in computational bioinformatics and "big data" processing have contributed immensely to individualized/personalized medicine in the developed world.

MAIN BODY

At the dawn of precision medicine, various omics-based therapies and bioengineering can now be applied accurately for the diagnosis, prognosis, treatment, and risk stratification of cancer in a manner that was hitherto not thought possible. The widespread introduction of genomics and other omics-based approaches into the postgraduate training curriculum of diverse medical and dental specialties, including pathology has improved the proficiency of practitioners in the use of novel molecular signatures in patient management. In addition, intricate details about disease disparity among different human populations are beginning to emerge. This would facilitate the use of tailor-made novel theranostic methods based on emerging molecular evidences.

CONCLUSION

In this review, we examined the challenges and prospects of using currently available omics-based technologies vis-à-vis oral pathology as well as prompt cancer diagnosis and treatment in a resource limited setting.

Malignant pericardial mesothelioma : A systematic review of current practice

BACKGROUND

Malignant mesothelioma is a rare but aggressive tumor, with a high misdiagnosis rate and overall bleak prognosis. In 0.7% of all cases, the origin is the pericardium.

METHODS

The present study is a review of the literature published in recent decades focusing on the advances in clinical manifestations, radiological findings, diagnosis, differential diagnosis, and treatment of malignant pericardial mesothelioma (MPM).

RESULTS

No clear relationship has been established between the etiologies and the development of MPM. Clinical symptoms and signs are nonspecific when present. The main presentations are chest pain and dyspnea. Imaging plays an important role in the detection, characterization, staging, and posttreatment follow-up. The definitive diagnosis is made on the basis of pathological findings. Chest radiography and echocardiography are common techniques used initially, but their roles are limited. Computed tomography and magnetic resonance imaging have an advantage in depicting the thickened pericardium, mediastinal lymph node, tumor, and the extension of adjacent structures. Surgery is the most important treatment modality and remains palliative in most cases, while the roles of chemo- and radiotherapy are unsatisfactory.

CONCLUSION

Clinical trials of malignant pleural and peritoneal mesothelioma remain important for MPM management. Multimodality treatment of surgery, chemotherapy, radiotherapy, and immunotherapy is expected to have a role in the treatment of MPM.

False-positive results in diagnostic immunohistochemistry are related to horseradish peroxidase conjugates in commercially available assays

False-positive results in diagnostic immunopathology can lead to unnecessary treatments. The purpose of this study was to do a side-by-side comparison of 10 different antibodies commonly used in the clinical laboratory altering only the horseradish peroxidase (HRP) conjugate. The automated Leica BOND-MAX platform was used to study serial sections from 203 tissues including controls compared in a blinded fashion using the HRP conjugates from Leica (Refine HRP), Ventana Medical Systems (Ultraview HRP), and Enzo Life Sciences (Polyview HRP). False-positive results, defined as signal from cases known to not contain the target, were noted in 23 (13%) of 171 cases with the Leica HRP, 62 (36%) of 171 cases with the Ventana HRP, and no cases with the Enzo HRP. Each data set was performed simultaneously allocating 1 tray for each of the 3 different HRP conjugates. HER2/neu analysis from triple-negative breast cancers were scored as positive by immunohistochemistry in 6 (24%) of 25 cases using either the Refine or Ultraview HRP and in 0 of 25 cases with the Enzo conjugate. It is concluded that false-positive results in a wide spectrum of diagnostic immunopathology tests can occur from 13% to 36% of cases with commonly used commercial assays based on the HRP conjugate.

Advances in malignant peritoneal mesothelioma

BACKGROUND

Malignant mesothelioma is a rare, insidious, and aggressive tumor arising from the mesothelial surface of pleural and peritoneal cavities, the pericardium, or the tunica vaginalis, with an increasing incidence worldwide, high misdiagnosis rate, and overall negative prognosis. A total of 20% of all cases is peritoneum in origin.

METHODS

The present study is a review of literatures focusing on the advances in epidemiology, clinical presentations, radiological features, diagnosis, misdiagnosis, management, and prognostic factors of malignant peritoneal mesothelioma (MPM) occurred in the past decades.

RESULTS

Asbestos, SV40, and radiation exposures have been demonstrated to be correlated with the pathogenesis of MPM. The main presentations are abdominal distension and pain. Computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET) play an important role in the preoperative imaging and staging. Definitive diagnosis is made on the basis of immunohistochemistry. Prognostic factors have been identified and verified. Negative indicators include advanced age, male gender, poor performance status, non-epithelial histology, and absence of surgery. The management of MPM has evolved from single chemotherapy to multimodality treatment of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), chemotherapy, radiotherapy, and immunotherapy. Promising results have been achieved after a combined treatment of CRS and HIPEC, with an elevated median survival time of 29.5-92 months and a 5-year survival rate of 39-63%.

CONCLUSIONS

CRS and HIPEC represent the standard treatment strategy for selected patients with MPM, and patients with unresectable tumors can benefit from the combined treatment of chemotherapy, radiotherapy, and immunotherapy.

Adrenocorticotropic hormone-producing thymic neuroendocrine carcinoma with oncocytic features: a case report and review of literature

Thymic neuroendocrine carcinomas are the most common mediastinal neuroendocrine tumor. These malignancies are not often diagnosed by fine-needle aspiration (FNA), as they are more commonly diagnosed by biopsy or excision. We describe a case of a FNA of a paratracheal mass from a 38-year-old man who presented with Cushing syndrome. A low-grade neuroendocrine carcinoma with oncocytic features was diagnosed, which was later confirmed by excision of the thymus, anterior mediastinal and paratracheal soft tissue, and lymph nodes. Oncocytic features in these tumors are a rare finding and bring metastatic medullary thyroid carcinomas as well as other metastases into the differential diagnosis. The prognosis of neuroendocrine carcinomas in this location is worse than neuroendocrine carcinomas in other areas, and close follow-up is recommended.

[Pleural mesothelioma. Cytology and molecular diagnostics]

The definitive diagnosis of malignant mesothelioma (MM) in effusion cytology is often avoided or reluctantly made by cytology alone. The most probable reason for this skepticism is the lack of expertise in cytology among many pathologists and clinicians. When an effusion specimen is composed of cells with unequivocal cytological features of malignancy that have the morphology and immunophenotype of mesothelial cells, the cytological diagnosis of MM is straightforward. However, in the daily routine difficult cases of atypical mesothelial cells are often encountered and additional methods are required to establish an accurate diagnosis. In contrast to reactive mesothelial cells cells of MMs often harbor chromosomal aberrations, most frequently a polysomy in combination with a 9p21 deletion. These chromosomal aberrations can easily be detected by multitarget fluorescence in situ hybridization (FISH); therefore, FISH allows a reliable distinction between reactive mesothelial cells and MM cells. In order to be able to discriminate between MM and adenocarcinoma, an immunocytochemical panel consisting of different mesothelial and epithelial markers is very helpful. In most inconclusive cases of atypical mesothelial cells the combination of morphology, immunocytochemistry and FISH allows a better distinction between reactive mesothelial cells and MM in effusion cytology.

Malignant paratesticular mesothelioma

Mesothelioma of the tunica vaginalis testis (MTVT) is a rare tumor that usually affects patients after the sixth decade of life. Exposure to asbestos is a known risk factor. Enlargement of the scrotal volume is the most common initial clinical manifestation, and about 15% of cases present metastasis at diagnosis. The treatment relies on surgical resection while the role of adjuvant chemotherapy and radiotherapy remains unclear. The prognosis for patients is generally poor, with a lethal outcome in 30% over a 24-month period. The authors report a case of a 62-year-old patient with the diagnosis of MTVT without a history of asbestos exposure. After surgical treatment, metastatic disease ensued. Chemotherapy was initiated, but could not be continued due to marked and fast clinical deterioration. The authors call attention to the difficulty of early diagnosis of MTVT due to a nonspecific clinical picture, the lack of action by the patient when the scrotal enlargement was first noticed, and the lack of tumor markers. Delayed diagnosis is definitely related to unfavorable prognosis.

Malignant paratesticular mesothelioma

Mesothelioma of the tunica vaginalis testis (MTVT) is a rare tumor that usually affects patients after the sixth decade of life. Exposure to asbestos is a known risk factor. Enlargement of the scrotal volume is the most common initial clinical manifestation, and about 15% of cases present metastasis at diagnosis. The treatment relies on surgical resection while the role of adjuvant chemotherapy and radiotherapy remains unclear. The prognosis for patients is generally poor, with a lethal outcome in 30% over a 24-month period. The authors report a case of a 62-year-old patient with the diagnosis of MTVT without a history of asbestos exposure. After surgical treatment, metastatic disease ensued. Chemotherapy was initiated, but could not be continued due to marked and fast clinical deterioration. The authors call attention to the difficulty of early diagnosis of MTVT due to a nonspecific clinical picture, the lack of action by the patient when the scrotal enlargement was first noticed, and the lack of tumor markers. Delayed diagnosis is definitely related to unfavorable prognosis.

Use of automated image analysis in evaluation of Mesothelioma Tissue Microarray (TMA) from National Mesothelioma Virtual Bank

The National Mesothelioma Virtual Bank (NMVB) was established to provide annotated biospecimens to the mesothelioma research community. The resource provides tissue microarrays (TMA) to evaluate the biomarkers along with a variety of other resected mesothelioma specimens. In this manuscript, we describe the immunohistochemical evaluation of the mesothelioma TMA with three key antibodies that are used in making the diagnosis of mesothelioma, and compared the immunohistochemical assessment between manual scoring and image analysis. The TMA was assessed for the immunohistochemical expression of calretinin (N=39), cytokeratin (CK) 5/6 (N=33), and D2-40 (N=37). Immunohistochemistry was evaluated by semi-quantitative (manual) scoring using light microscope (MS) and by automated image analysis (AS). Calretinin staining was seen in both cytoplasmic and nuclear locations. CK5/6 stain was localized to the cytoplasm. D2-40 stain showed only membranous expression in our cases. • Based on the pathologist’s scores, calretinin was positive in 31 of the 39 cases (80%), CK 5/6 in 15 of the 33 cases (46%) and D2-40 in 18 of the 37 cases (49%). • The percent-positive agreement between manual scores and image analysis was 90% (35/39), 94% (31/33), and 95% (35/37) for calretinin, CK 5/6, and D2-40, respectively. There was a substantial agree-ment between manual and automated scores for calretinin (kappa = 0.614) and an almost perfect agreement for CK5/6 (kappa = 0.879) and D2-40 (kappa = 0.892). Our study confirms that the immunohistochemical staining pattern of mesotheliomas in the NMVB UPMC TMA is similar to other studies. Our findings also show that automated image analysis provides similar results to manual scoring by pathologists, and provides a reproducible, objective, and accurate platform for immunohistochemical assessment of biomarker expression.

Abdominopelvic washings: A comprehensive review

Intraperitoneal spread may occur with gynecological epithelial neoplasms, as well as with non-gynecological malignancies, which may result in serosal involvement with or without concomitant effusion. Therefore, washings in patients with abdominopelvic tumors represent important specimens for cytologic examination. They are primarily utilized for staging ovarian cancers, although their role has decreased in staging of endometrial and cervical carcinoma. Abdominopelvic washings can be positive in a variety of pathologic conditions, including benign conditions, borderline neoplastic tumors, locally invasive tumors, or distant metastases. In a subset of cases, washings can be diagnostically challenging due to the presence of co-existing benign cells (e.g., mesothelial hyperplasia, endosalpingiosis, or endometriosis), lesions in which there is only minimal atypia (e.g., serous borderline tumors) or scant atypical cells, and the rarity of specific tumor types (e.g., mesothelioma). Ancillary studies including immunocytochemistry and fluorescence in situ hybridization may be required in difficult cases to resolve the diagnosis. This article provides a comprehensive and contemporary review of abdominopelvic washings in the evaluation of gynecologic and non-gynecologic tumors, including primary peritoneal and mesothelial entities.

GENE EXPRESSION DATA CLASSIFICATION COMBINING HIERARCHICAL REPRESENTATION AND EFFICIENT FEATURE SELECTION

A general framework for microarray data classification is proposed in this paper. It produces precise and reliable classifiers through a two-step approach. At first, the original feature set is enhanced by a new set of features called metagenes. These new features are obtained through a hierarchical clustering process on the original data. Two different metagene generation rules have been analyzed, called Treelets clustering and Euclidean clustering. Metagenes creation is attractive for several reasons: first, they can improve the classification since they broaden the available feature space and capture the common behavior of similar genes reducing the residual measurement noise. Furthermore, by analyzing some of the chosen metagenes for classification with gene set enrichment analysis algorithms, it is shown how metagenes can summarize the behavior of functionally related probe sets. Additionally, metagenes can point out, still undocumented, highly discriminant probe sets numerically related to other probes endowed with prior biological information in order to contribute to the knowledge discovery process.

The second step of the framework is the feature selection which applies the Improved Sequential Floating Forward Selection algorithm (IFFS) to properly choose a subset from the available feature set for classification composed of genes and metagenes. Considering the microarray sample scarcity problem, besides the classical error rate, a reliability measure is introduced to improve the feature selection process. Different scoring schemes are studied to choose the best one using both error rate and reliability. The Linear Discriminant Analysis classifier (LDA) has been used throughout this work, due to its good characteristics, but the proposed framework can be used with almost any classifier. The potential of the proposed framework has been evaluated analyzing all the publicly available datasets offered by the Micro Array Quality Control Study, phase II (MAQC). The comparative results showed that the proposed framework can compete with a wide variety of state of the art alternatives and it can obtain the best mean performance if a particular setup is chosen. A Monte Carlo simulation confirmed that the proposed framework obtains stable and repeatable results.

Clinical, histologic, and genetic features of mesothelioma in a 7-year-old child

Malignant mesothelioma (MM) is a highly aggressive malignancy that is extremely rare in children. This case report documents a 7-year-old male without previous asbestos exposure with peritoneal MM that initially responded to chemotherapy with cisplatin and gemcitabine but ultimately metastasized to his chest. He was diagnosed with MM based on histology, extensive immunohistochemical analyses, and an elevated serum CA-125 level. Cytogenetics and comparative genomic hybridization (CGH) analysis of his tumor identified a single extra copy number of chromosome 11 with few other changes noted.

Peritoneal fibrosarcomatous mesothelioma in a cat

Primary tumors of serosal surfaces are uncommon in veterinary medicine. Mesothelial neoplasms can be benign or malignant, and are classified as predominantly epitheloid, mixed (biphasic), or fibrous (spindle cell, fibrosarcomatous), with fibrous mesotheliomas reported least in domestic species. A 9-year-old Domestic Shorthair cat presented on emergency with a brief history of weakness and lethargy. On presentation, the cat was semicomatose, hypothermic, and hypotensive with a markedly distended abdomen. Approximately 1 liter of serosanguineous fluid was removed via abdominocentesis. Diagnostic imaging and cytologic evaluation of fine-needle aspirates were suggestive of neoplasia, and the cat was subsequently euthanized. At necropsy, the omentum was contracted cranially into an irregular lobular mass that surrounded the stomach and proximal intestinal tract, and focally infiltrated the spleen. Both visceral and parietal peritoneal surfaces were thickened and contained off-white friable material and occasionally firm fibrous plaques. Microscopically, serosal surfaces were expanded by neoplastic spindle cells, which were often accompanied by moderate to abundant fibrous stroma. Neoplastic cells had varying degrees of immunoreactivity for cytokeratin, vimentin, desmin, and smooth muscle actin, which was consistent with the diagnosis of mesothelioma.

Expression of the Ets transcription factor EHF in serous ovarian carcinoma effusions is a marker of poor survival

The EHF (Ets homologous factor) gene was previously shown to be overexpressed in ovarian/primary peritoneal serous carcinoma compared to malignant mesothelioma using gene expression arrays. The objective of this study was to validate this finding at the mRNA level in a larger series. We analyzed the diagnostic role of EHF in 98 ovarian serous carcinoma effusions, 23 malignant mesothelioma specimens (20 effusions, 3 surgical specimens), and 28 primary ovarian serous carcinomas using quantitative real-time polymerase chain reaction. Expression levels of EHF in ovarian carcinoma were additionally investigated for association with clinicopathologic parameters and survival. Quantitative real-time polymerase chain reaction analysis showed significantly higher expression of EHF mRNA in ovarian carcinoma effusions and in primary ovarian carcinoma compared to malignant mesothelioma effusions (P < .001 for both). EHF mRNA expression was additionally higher in primary ovarian carcinomas compared to effusions of this cancer (P < .001). In univariate analysis for all patients with effusions, higher EHF mRNA levels were associated with a trend for shorter progression-free survival (P = .066), which became significant in analysis of 45 patients with primary diagnosis pre-chemotherapy effusions (P = .01). In Cox multivariate analysis, EHF mRNA expression was an independent predictor of poor progression-free survival for all patients and patients with primary diagnosis pre-chemotherapy effusions (P = .033 and P = .009, respectively). EHF mRNA levels differentiate ovarian carcinoma from malignant mesothelioma and may thus be of diagnostic value in this setting. EHF may be a novel prognostic marker in ovarian carcinoma.

PINCH-2 expression in cancers involving serosal effusions using quantitative PCR

OBJECTIVE

The PINCH-2 gene was previously shown to be overexpressed in malignant mesothelioma compared with ovarian/peritoneal serous carcinoma in Affymetrix array analysis. The objective of the present study was to validate this finding at the mRNA and protein level.

METHODS

Effusions (n = 91; 71 ovarian and 10 breast carcinomas, 10 malignant mesotheliomas) were assayed for PINCH-2 mRNA expression using quantitative PCR. PINCH-2 protein expression was analysed in 37 effusions using flow cytometry.

RESULTS

Quantitative PCR analysis showed significantly higher PINCH-2 mRNA levels in mesotheliomas compared with carcinomas (P = 0.004). Values of <10 copies were found exclusively in carcinoma effusions (25.4% of ovarian and 50% of breast carcinomas). However, PINCH-2 protein expression by flow cytometry did not differ significantly between the three cancer types. No association was observed between PINCH-2 levels and patient survival or expression of previously-studied molecules related to adhesion, metastasis and apoptosis inhibition in ovarian carcinoma.

CONCLUSIONS

Our data suggest that PINCH-2 mRNA is overexpressed in malignant mesothelioma compared with carcinomas involving serosal cavities, and that low levels of this gene argue against the diagnosis of mesothelioma. The frequent PINCH-2 protein expression in all three studied cancers suggests a role for this molecule in cancer cell biology in effusions and merits further research.

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.

Occupational toxicology of asbestos-related malignancies

INTRODUCTION

Asbestos is banned in most Western countries but related malignancies are still of clinical concern because of their long latencies. This review identifies and addresses some controversial occupational and clinical aspects of asbestos-related malignancies.

METHODS

Papers published in English from 1980 to 2009 were retrieved from PubMed. A total of 307 original articles were identified and 159 were included.

ASSESSMENT OF EXPOSURE

The retrospective assessment of exposure is usually performed by using questionnaires and job exposure matrices and by careful collection of medical history. In this way crucial information about manufacturing processes and specific jobs can be obtained. In addition, fibers and asbestos bodies are counted in lung tissue, broncho-alveolar lavage, and sputum, but different techniques and interlaboratory variability hamper the interpretation of reported measurements. SCREENING FOR MALIGNANCIES: The effectiveness of low-dose chest CT screening in exposed workers is debatable. Several biomarkers have also been considered to screen individuals at risk for lung cancer and mesothelioma but reliable signatures are still missing. ATTRIBUTION OF LUNG CANCER: Exposures correlating with lung cancer are high and in the same range where asbestosis occurs. However, the unresolved question is whether the presence of fibrosis is a requirement for the attribution of lung cancer to asbestos. The etiology of lung cancer is difficult to define in cases of low-level asbestos exposure and concurrent smoking habits. MESOTHELIOMA: The diagnosis of malignant mesothelioma may also be difficult, because of procedures in sampling, fixation, and processing, and uses of immunohistochemical probes.

CONCLUSIONS

Assessment of exposure is crucial and requires accurate medical and occupational histories. Quantitative analysis of asbestos body burden is better performed in digested lung tissues by counting asbestos bodies by light microscopy and/or uncoated fibers by transmission electron microscopy. The benefits of screenings for asbestos-related malignancies are equivocal. The attribution of lung cancer to asbestos exposure is difficult in a clinical setting because of the need to assess asbestos body burden and the fact that virtually all these patients are also tobacco smokers or former smokers. Given the premise that asbestosis is necessary to causally link lung cancer to asbestos, it follows that the assessment of both lung fibrosis and asbestos body burden is necessary.

Re-evaluation of histological diagnoses of malignant mesothelioma by immunohistochemistry

Background

In order to provide reliable tissue material for malignant mesothelioma (MM) studies, we re-evaluated biopsies and autopsy material from 61 patients with a diagnosis of MM from the period of 1980-2002.

Methods

Basic positive (Calretinin, EMA, Podoplanin, Mesothelin) and negative (CEA, Ber-Ep4) immunohistochemical (IHC) marker reactions were determined. If needed, more markers were used. Histological diagnoses were made by three pathologists. Survival data were calculated.

Results

49 cases (80%) were considered being MM by a high degree of likelihood, five more cases possible MM. Of the remaining seven cases, three were diagnosed as adenocarcinoma, three as pleomorphic lung carcinoma, in one peritoneal case a clear entity diagnosis could not be given. One of the possible MM cases and two of the lung carcinoma cases had this already as primary diagnoses, but were registered as MM.

With a sensitivity of 100%, Calretinin and CEA were the most reliable single markers. The amount of MM cells with positive immunoreactivity (IR) for Podoplanin and Mesothelin showed most reliable inverse relation to the degree of atypia.

In the confirmed MM cases, there had been applied either no IHC or between one and 18 markers.

The cases not confirmed by us had either lacked IHC (n = 1), non-specific markers were used (n = 4), IR was different (n = 1), or specific markers had not shown positive IR in the right part of the tumour cells (n = 3).

46 of the 49 confirmed and three of the not confirmed cases had been diagnosed by us as most likely MM before IHC was carried out.

Conclusions

In order to use archival tissue material with an earlier MM diagnosis for studies, histopathological re-evaluation is important. In possible sarcomatous MM cases without any positive IR for positive MM markers, radiology and clinical picture are essential parts of diagnostics. IHC based on a panel of two positive and two negative MM markers has to be adapted to the differential diagnostic needs in each single case. New diagnostic tools and techniques are desirable for cases where IHC and other established methods cannot provide a clear entity diagnosis, and in order to improve MM treatment.

Benign and Malignant Mesothelial Proliferation

Malignant mesothelioma (MM) is a rare primary malignant tumor of the surface serosal cells. The diagnosis of MM is challenging with a broad differential diagnosis. For many decades, studies have focused on distinguishing MM from other types of cancer; however, benign mesothelial cell hyperplasia, especially in small biopsies, has emerged as a major problem. The features of pleural lesions are somewhat different from peritoneal diseases, and this article primarily focuses on pleural diseases. Thorough interpretation and correlation of clinical, radiologic, and pathologic findings are essential for a correct diagnosis.

Fluorescence in situ hybridization in the definitive diagnosis of malignant mesothelioma in effusion cytology

BACKGROUND

Distinction of malignant mesothelioma (MM) from reactive mesothelial cells (RM) in effusions is notoriously difficult. The aim of our study was to test chromosomal aberrations detected by fluorescence in situ hybridization (FISH) in the diagnosis of MM in effusion cytology and to explore the potential role of p16, p14, and p15 gene methylation as an alternative mechanism of tumor suppressor gene inactivation.

METHODS

Fifty-two effusions of biopsy-proven MM and 28 benign effusions were retrospectively analyzed by multitarget FISH assay for aberrations of chromosomes 3, 7, 17, and 9p21. In case of a negative result, the corresponding MM biopsy specimen was analyzed. Methylation-specific polymerase chain reaction (MSP) for p16, p14, and p15 was performed on FISH-negative MM biopsy specimens.

RESULTS

Seventy-nine percent of effusions with biopsy-proven MM had chromosomal aberrations, with loss of 9p21 as the most common finding. All benign effusions were FISH negative. Sensitivity, specificity, and positive and negative predictive values for detection of MM by FISH were 79%, 100%, 100%, and 72%, respectively. Six of nine FISH-negative effusions with biopsy-proven MM were also FISH negative in the MM biopsy specimens. Four of five FISH-negative biopsy specimens showed promoter methylation in p16 and p14 as compared with one of 12 benign controls.

CONCLUSIONS

FISH is a sensitive and highly specific method for the definitive diagnosis of MM in effusion cytology. In the subset of FISH-negative MM, tumor suppressor genes on the chromosomal region 9p21 are often inactivated by promoter methylation.

Paratesticular mesothelioma. Report of a case with comprehensive review of literature

Paratesticular mesotheliomas are rare tumors with 223 cases described so far. The sole plausible causative factor so far ascertained in the pathogenesis of these tumors is asbestos, which however is found in only around 30% to 40% of such cases. The age range of affected individuals is wide, mostly adults and the elderly, but also includes young people and children. The most common presenting symptom is either hydrocele of unknown origin or intrascrotal mass. When hydrocele is the presenting symptom, these tumors are often clinically overlooked and the diagnosis is delayed. Most paratesticular mesotheliomas arise in the tunica vaginalis, but primary tumors of the spermatic cord and epididymis are also on record. Tumors arising from the peritoneal mesothelium of a hernia sac are excluded from this group. The correct diagnosis is almost always made after histologic examination of the operative specimen. Immunohistochemistry and electron microscopy are always helpful and sometimes necessary tools for diagnosis. So far very few cases have been identified or suspected preoperatively on cytologic examination. Three clinicopathologic types of malignant mesotheliomas of the male genital tract are recognized: diffuse tubulo-papillary mesothelioma, well-differentiated papillary mesothelioma, and multicystic mesothelioma. The histologic subtypes are almost always pure epithelial or biphasic. The differential diagnosis is mainly with serous papillary tumors arising from Mullerian vestiges, but several diverse primary or secondary tumors also need to be considered. A clinicopathologic evaluation of a case of tunical diffuse mesothelioma in a 74-year-old male from the AMR Series is the starting point for this general review.

Tenascin-X is a novel diagnostic marker of malignant mesothelioma

Tenascin XB (TNXB) was previously identified as a gene that is more highly expressed in malignant mesothelioma compared with ovarian/peritoneal serous carcinoma based on gene expression array analysis. The objective of this study was to validate this finding at the mRNA and protein levels. Effusions (n = 91; 71 ovarian carcinomas, 10 breast carcinomas, and 10 malignant mesotheliomas) were assayed for TNXB mRNA expression using quantitative polymerase chain reaction. Tenascin-X protein expression was studied in 183 effusions (137 carcinomas of different origin, 37 mesotheliomas, and 9 reactive effusions) and 178 solid lesions (122 ovarian/peritoneal carcinomas and 56 mesotheliomas) using immunohistochemistry. Quantitative polymerase chain reaction analysis showed significantly higher TNXB mRNA level in mesotheliomas compared with ovarian and breast carcinomas (P < 0.001). By immunohistochemistry, tenascin-X protein expression was significantly higher in malignant mesothelioma compared with metastatic carcinoma in effusions (34 of 37 vs. 31 of 137 positive cases; sensitivity = 92% and specificity = 77%; P < 0.001). Reactive mesothelial cells had focal or no tenascin-X expression. Tenascin-X protein was detected in 41 of 56 mesothelioma biopsy specimens and was uniformly absent from all 122 ovarian carcinomas (sensitivity = 73% and specificity = 100%; P < 0.001). Our data suggest that tenascin-X may be a new diagnostic marker of malignant mesothelioma in the differential diagnosis of cancers involving the serosal cavities, particularly in the differential diagnosis between this tumor and ovarian/peritoneal serous carcinoma.

Protein profiling of pleural effusions to identify malignant pleural mesothelioma using SELDI-TOF MS

Diagnosis of malignant pleural mesothelioma (MM) is limited. Novel proteomic techno_logies can be utilized to discover changes in expression of pleural proteins that might have diagnostic value. The objective of this study was to detect protein profiles that could be used to identify malignant pleural mesothelioma with surface enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS). Pleural effusions were collected from patients with confirmed mesothelioma (n = 41) and from patients with effusions due to other causes ([n = 48] cancerous and non-cancerous). Samples were fractionated using anion exchange chromatography and bound to different types of ProteinChip array surfaces. All samples were also subjected to other commercially available immunoassays (human epididymes protein 4 [HE4], osteopontin [OPN], soluble mesothelin-related proteins [SMRP], and the cytokeratin 19 fragment [CYFRA 21-1]). Peak intensity data obtained by SELDI-TOF were subjected to classification algorithms in order to identify potential classifier peaks. A protein peak at m/z 6614 was characterized as apolipoprotein (Apo) CI. In this setting, the sensitivity and specificity of this potential biomarker was 76 % and 69 %, respectively. The area under the receiver operating characteristic curve (AUC) for Apo CI was 0.755, thereby outperforming OPN, HE4, and CYFRA 21-1. SMRP performed best with an AUC of 0.860 with a sensitivity of 83% and specificity of 74%. Our study validates the use of SMRP as a diagnostic marker for pleural mesothelioma and furthermore suggests that Apo CI levels could be used in the future to discriminate pleural mesothelioma from other causes of exudates.

Cystic lymphangioma-like adenomatoid tumor of the adrenal gland: Case presentation and review of the literature

Adenomatoid tumors (AT) are usually found in the genital tract of both sexes. They are very rarely located in extragenital sites, and are exceedingly rare in the adrenal. AT of the adrenal gland (AT-AG) are nonfunctioning, usually discovered incidentally and confused on imaging with other more common adrenal neoplasms. The overwhelming majority occur in males. Thirty-four cases have been reported so far, more often presenting grossly as solid tumors, rarely as solid with cystic areas, and 5 cases were almost entirely cystic. At histology they can be either circumscribed or locally infiltrative, and may pose diagnostic difficulties when the pathologist relies on morphology alone or is challenged on frozen section. On light microscopy the diagnosis may be very difficult if the tumor is rich in vacuolated cells, mimicking metastatic signet ring-cell adenocarcinoma. Immunophenotyping and/or electron microscopy are paramount in helping to ascertain their mesothelial lineage. Lymphangioma is the main histologic mimic of solid-cystic and cystic AT-AG, but lymphangioma is immunopositive for endothelial markers and negative for cytokeratins and mesothelial markers. Ultrastructural analysis has been performed in 10 published cases of AT-AG, in all of which the classical microvilli of coelomic type were always observed. In brief we report herein the sixth case of cystic lymphangioma-like AT, which was incidentally discovered during clinical follow-up in a 39-year-old man undergoing cancer staging and surveillance after surgery. The adrenal tumor was 5.5 cm in size and was fully investigated immunohistochemically and ultrastructurally. A complete review of the literature is also presented.

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.

Problems in mesothelioma diagnosis

Many centres are now seeing increasing numbers of patients with malignant mesothelioma. This presents pathologists involved in making the diagnosis with a number of problems, which can be divided into those encountered in making the distinction between mesothelioma and benign changes and those experienced in separating mesotheliomas from other types of epithelial and connective tissue tumours. Immunohistochemistry plays a major role in helping to make the diagnosis, but it should be interpreted with due regard to the clinical setting and radiological features, and with a knowledge of the wide morphological variations seen in mesothelioma. This review identifies some of these problems and addresses the uses and limitations of immunohistochemistry in different situations. It includes a discussion of some of the less common variants of mesothelioma and other pleural-based tumours that enter into the differential diagnosis.

Application of immunohistochemistry to the diagnosis of malignant mesothelioma

CONTEXT

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

OBJECTIVE

To identify optimal antibody panels for the diagnosis of MM.

DATA SOURCES

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

CONCLUSIONS

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

Undifferentiated tumor: true identity by immunohistochemistry

CONTEXT

"Undifferentiated tumor" refers to a heterogeneous group of neoplasms with little or no evidence of differentiation on routine light microscopic morphology.

OBJECTIVE

To identify the true identity of undifferentiated tumors by immunohistochemical analysis.

DATA SOURCES

Review of the pertinent literature and the authors' experience.

CONCLUSIONS

For treatment and prognostic evaluation, it is crucial to delineate whether an undifferentiated neoplasm is epithelial, mesenchymal, melanocytic, or hematopoietic in nature. Application of a screening panel to demonstrate the expression of markers of major lineages is fundamental for determination of the broad category of neoplasia. Because poorly differentiated carcinomas and in particular sarcomatoid carcinomas are known to be heterogeneous in their antigen expression, several epithelial markers in combination may be required to establish the carcinomatous nature of tumor. A diagnostic misinterpretation as a consequence of occasional aberrant or unexpected antigen expression is best avoided by using a broad panel that includes both antibodies that are anticipated to be positive and those that are expected to be negative. In this treatise, the immunohistochemical dissection of undifferentiated tumors on the basis of their morphologic features is outlined, supplemented with algorithmic immunohistochemical analysis for each morphologic category of small round cell tumors, carcinomatous tumors, sarcomatous (or sarcoma-like) tumors, and tumors with histologically overlapping features, including hematolymphoid malignancies, melanoma, and sarcomas with epithelioid appearance. The utility of several organ- or tissue-specific markers in the context of undifferentiated tumors is reviewed.

Claudin 4 identifies a wide spectrum of epithelial neoplasms and represents a very useful marker for carcinoma versus mesothelioma diagnosis in pleural and peritoneal biopsies and effusions

We evaluated the usefulness of the tight-junction associated protein Claudin 4 (CL-4) in the diagnosis of mesothelioma and mimickers, analyzing biopsies from 454 tumors, including 82 mesotheliomas, 336 carcinomas of different origin (278 primary, 58 metastatic to serosae), 36 nonepithelial spindle cell neoplasms, as well as 97 cytological samples from reactive effusions (12), mesothelioma (23) and metastatic carcinomas (62). CL-4 was consistently negative in normal and reactive mesothelium, as well as in all 82 mesotheliomas. In contrast, strong reactivity was found in 57/58 serosal metastasis, and in 245/278 primary carcinomas, with uppermost expression (150/153) in those most frequently involved in the differential with mesothelioma (lung, breast, gastrointestinal tract, pancreas, ovary, primary serous papillary carcinoma of peritoneum). On effusions, reactive and neoplastic mesothelial cells were regularly negative, while metastatic tumor cells stained positively in 60/62 (96.8%) cases. Among spindle cell neoplasms, only 2/9 biphasic synovial sarcomas and 4/4 follicular dendritic cell sarcomas stained positively. Results indicate that CL-4 reacts with the majority of epithelial neoplasms that often metastasize to serous membranes, representing a pancarcinoma marker with extremely high sensitivity and specificity. CL-4 may be considered a primary immunohistochemical reagent to rule out the diagnosis of mesothelioma.

Benign glandular inclusion in obturator lymph node of a man treated for prostate carcinoma

Benign glandular inclusions in lymph nodes are extremely rare in men. Their identification is essential because it changes dramatically the prognosis and therapy of neoplasms. Described herein is the first case of benign glandular inclusion in an obturator lymph node dissected during a radical prostatectomy for treatment of prostate adenocarcinoma. A 60-year-old man underwent radical prostatectomy and obturator-hypogastric lymph node dissection for treatment of prostate adenocarcinoma. Benign glandular inclusion was found in microscopic examination. The lesion was characterized by two glandular spaces lined by a single, cuboid, benign epithelium localized in the sinus of one of four dissected lymph nodes. Immunohistochemistry showed mesothelial differentiation. Pathologists should be aware of benign glandular inclusion in obturator lymph nodes dissected during a radical prostatectomy for treatment of prostate cancer in order to avoid the incorrect diagnosis of metastatic disease.

Fine-needle aspiration of malignant mesothelioma with unusual morphologic features: A case report

Malignant mesothelioma is an aggressive neoplasm linked to asbestos exposure. Most mesothelioma patients present with pleural effusion and the fluid is typically sent for cytological examination. Therefore, cytopathologists are most familiar with features of mesothelioma in fluid preparations. We present here a case of malignant mesothelioma with unusual cytological features diagnosed on FNA. The diagnosis was confirmed by immuno-histochemical and electron microscopic studies. In addition, we compare the cytomorphological features observed in malignant effusion versus fine-needle aspiration.