Guidelines for pathologic diagnosis of malignant mesothelioma: a consensus statement from the International Mesothelioma Interest Group

Recent Advances in Pathology of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICCA) is a malignant epithelial neoplasm characterized by biliary differentiation within the liver. ICCA is molecularly heterogeneous and exhibits a broad spectrum of histopathological features. It is a highly aggressive carcinoma with high mortality and poor survival rates. ICCAs are classified into two main subtypes: the small-duct type and large-duct types. These two tumor types have different cell origins and clinicopathological features. ICCAs are characterized by numerous molecular alterations, including mutations in KRAS, TP53, IDH1/2, ARID1A, BAP1, BRAF, SAMD4, and EGFR, and FGFR2 fusion. Two main molecular subtypes-inflammation and proliferation-have been proposed. Recent advances in high-throughput assays using next-generation sequencing have improved our understanding of ICCA pathogenesis and molecular genetics. The diagnosis of ICCA poses a significant challenge for pathologists because of its varied morphologies and phenotypes. Accurate diagnosis of ICCA is essential for effective patient management and prognostic determination. This article provides an updated overview of ICCA pathology, focusing particularly on molecular features, histological subtypes, and diagnostic approaches.

Asbestos burden in lungs of mesothelioma patients with pleural plaques, lung fibrosis and/or ferruginous bodies at histology: a postmortem SEM-EDS study

The causal attribution of asbestos-related diseases to past asbestos exposures is of crucial importance in clinical and legal contexts. Often this evaluation is made based on the history of exposure, but this method presents important limitations. To assess past asbestos exposure, pleural plaques (PP), lung fibrosis and histological evidence of ferruginous bodies (FB) can be used in combination with anamnestic data. However, such markers have never been associated with a threshold value of inhaled asbestos. With this study we attempted to shed light on the dose-response relationship of PP, lung fibrosis and FBs, investigating if their prevalence in exposed individuals who died from malignant mesothelioma (MM) is related to the concentration of asbestos in lungs assessed using scanning electron microscopy equipped with energy dispersive spectroscopy. Moreover, we estimated the values of asbestos concentration in lungs associated with PP, lung fibrosis and FB. Lung fibrosis showed a significant positive relationship with asbestos lung content, whereas PP and FB did not. We identified, for the first time, critical lung concentrations of asbestos related to the presence of PP, lung fibrosis and FB at histology (respectively, 19 800, 26 400 and 27 400 fibers per gram of dry weight), that were all well-below the background levels of asbestos identified in our laboratory. Such data suggest that PP, lung fibrosis and FB at histology should be used with caution in the causal attribution of MM to past asbestos exposures, while evaluation of amphibole lung content using analytical electron microscopy should be preferred.

The over diagnosis of diffuse mesothelioma: An analysis of 311 cases with recommendations for the avoidance of pitfalls

BACKGROUND

The diagnosis of mesothelioma may be challenging. We investigated a large database of cases in order to determine the frequency with which a diagnosis of mesothelioma was made incorrectly and the most frequent causes of error.

DESIGN

A database including more than 4000 consultation cases of histologically confirmed mesothelioma was examined to identify cases in which mesothelioma was diagnosed by at least one pathologist when the available information pointed towards a different diagnosis.

RESULTS

There were 311 cases misdiagnosed as mesothelioma. The most common category was metastatic carcinoma to the pleura or peritoneum (129 cases: 73 lung carcinomas, 15 renal cell carcinomas). The next most common category was primary lung cancer (111 cases: 55 sarcomatoid carcinoma, 56 pseudomesotheliomatous carcinoma). The third most common category was primary malignancies arising from or near the serosal membranes (33 cases). The fourth most common category was fibrous pleurisy (38 cases). The most common errors were failure to consider important radiographic information regarding the gross distribution of tumor, lack of awareness or consideration of another malignancy, overreliance on certain immunohistochemical results, and failure to perform certain diagnostic histochemical, immunohistochemical, or ultrastructural studies.

CONCLUSIONS

There are a number of diagnostic pitfalls that can lead to the over diagnosis of mesothelioma. Careful attention to clinical and radiographic information as well as performance of appropriate ancillary tests can help to prevent such misdiagnoses. Detailed examples will be presented to assist in the avoidance of these pitfalls with emphasis on the most commonly observed errors.

A postmortem case control study of asbestos burden in lungs of malignant mesothelioma cases

BACKGROUND

Asbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends.

METHODS

Asbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM-EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023.

RESULTS

Asbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011.

DISCUSSION

The results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011.

Comparison of immunohistochemical mesothelial biomarkers in paired biopsies and effusion cytology cell blocks from pleural mesothelioma

OBJECTIVE

Traditionally, the diagnosis of pleural mesothelioma is based on histological material. Minimally invasive effusion cytology specimens are an alternative that, like biopsies, require ancillary analyses. Validation of immunohistochemical (IHC) analyses on cytology, including the surrogate markers for molecular alterations BAP1 and MTAP, is of interest.

METHODS

IHC for eight different markers was performed on 59 paired formalin-fixed, paraffin-embedded pleural biopsies and pleural effusion cell blocks with mesothelioma. Immunoreactivity in ≥10% of tumour cells was considered positive/preserved. The concordance between histological and cytological materials was assessed.

RESULTS

The overall percentage of agreement between the histological epithelioid component in 58 biopsies and paired cell blocks was 93% for calretinin, 98% for CK5, 97% for podoplanin, 90% for WT1, 86% for EMA, 100% for desmin, 91% for BAP1, and 72% for MTAP. For 11 cases with biphasic or sarcomatoid histology, the concordance between cytology and the histological sarcomatoid component was low for calretinin, CK5, and WT1 (all ≤45%). For the whole cohort, loss of both BAP1 and MTAP was seen in 40% while both markers were preserved in 11% of the biopsies for epithelioid histology. The corresponding numbers were 54% and 8%, respectively, for the paired cell blocks.

CONCLUSIONS

Generally, a high concordance for IHC staining was seen between paired biopsies and pleural effusion cell blocks from mesotheliomas, but the somewhat lower agreement for WT1, EMA, and especially MTAP calls for further investigation and local quality assurance. The lower concordance for the sarcomatoid subtype for some markers may indicate biological differences.

Chronological trends in the causation of malignant mesothelioma: Fiber burden analysis of 619 cases over four decades

Malignant mesothelioma is a relatively rare malignancy with a strong association with prior asbestos exposure. A percentage of cases is not related to asbestos, and fiber analysis of lung tissue is a useful methodology for identifying idiopathic or spontaneous cases. We have performed fiber analyses in more than 600 cases of mesothelioma over the past four decades and were interested in looking for trends in terms of fiber types and concentrations as well as percentages of cases not related to asbestos. Demographic information was also considered including patient age, gender, and tumor location (pleural vs. peritoneal). The histologic pattern of the tumor and the presence or absence of pleural plaques or asbestosis were noted. Fiber analysis was performed in 619 cases, using the sodium hypochlorite technique for digestion of lung tissue samples. Asbestos bodies were counted by light microscopy (LM) and coated and uncoated fibers by scanning electron microscopy (EM). The results were stratified over four decades. Trends that were observed included increasing patient age, increasing percentage of women, increasing percentage of peritoneal cases, and increasing percentage of epithelial histological type. There was a decreasing trend in the percentage of patients with concomitant asbestosis (p < 0.001). The percentage of cases with an elevated lung asbestos content decreased from 90.5% in the 1980s to 54.1% in the 2010s (p < 0.001). This trend also held when the analysis was limited to 490 cases of pleural mesothelioma in men (91.8% in the 1980s vs. 65.1% in the 2010s). There was a decrease in the median asbestos body count by LM from 1390 asbestos bodies per gram of wet lung in the 1980s to 38 AB/gm in the 2010s. Similar trends were observed for each of the asbestos fiber types as detected by EM. We conclude that there has been a progressive decrease in lung fiber content of mesothelioma patients during the past four decades, with an increasing percentage of cases not related to asbestos and an increase in median patient age.

Extrapelvic Endometriosis Mimicking Peritoneal Surface Malignancy: Case Report and a Review of Literature

Extrapelvic endometriosis is a rare presentation of endometriosis with atypical clinical symptoms. It can mimic peritoneal surface malignancy, as well as some abdominal infectious diseases. A 29-year-old Moroccan woman presented with abdominal pain, progressive abdominal distention, and an intermittent inflammatory syndrome. Imaging revealed multiple, progressively growing abdominal cysts. She had elevated tumor markers CA125 and CA19.9. Despite thorough investigation, several differential diagnoses persisted for a long time. Definitive pathological diagnosis could only be established after debulking surgery. Literature review on malignant and benign conditions causing multicystic abdominal distention is provided. When definitive diagnosis is not established, but suspicion for peritoneal malignancy remains, a debulking procedure can be undertaken. Organ preservation can be pursued whenever benign disease is still considered. In case of malignancy, short-term (curative) debulking procedure with or without hyperthermic intraperitoneal chemotherapy (HIPEC) can be proposed.

Reconstructing historical exposure to asbestos: the validation of 'educated guesses'

BACKGROUND

In both the epidemiological and legal context, the causal attribution of asbestos-related lung diseases requires retrospective exposure assessment (REA).

AIMS

To assess the correlation between the retrospective assessment of occupational and anthropogenic environmental exposure to asbestos and its content in the lung tissue.

METHODS

Based on the available exposure information, a team of occupational physicians retrospectively assessed cumulative exposure to asbestos in 24 subjects who died of asbestos-related diseases. The asbestos lung content was analysed using analytical scanning electron microscope (SEM-EDS). The Log10 asbestos fibre count in the autoptic samples was predicted as a function of the Log10 estimated cumulative exposure using univariate regression analysis.

RESULTS

The median count of asbestos fibres by grams of dry weight (ff/gdw) in the lung tissue was 81 339 (range 0-2 135 849.06); it was 287 144 (range 0-2 135 849.06) among the occupationally exposed, and 29 671 (range 0-116 891) among the subjects who only had anthropogenic environmental and/or household exposure. Amphiboles, and particularly amosite (52%) and crocidolite (43%), were detected in all the study subjects. Chrysotile was not detected in any of the samples. Overall, the retrospective estimate of lifetime cumulative exposure to asbestos showed a moderate correlation with the total asbestos fibre count in the autoptic lung, with the regression model explaining 38-55% of the total variance.

CONCLUSIONS

Detailed information on occupational, environmental and household exposure circumstances would be indispensable for experienced industrial hygienists and/or occupational physicians to reliably assess past exposure to amphiboles or mixed types of asbestos.

Mediastinal Serous Cavity Mesothelioma in Two Dogs

The mediastinal serous cavity (MSC)-well documented but seldom recognized in the caudal mediastinum-is embryologically derived from the omental bursa. Mesothelioma arising from the MSC in two dogs is described. Both dogs presented with acute life-threatening hemorrhagic pleural effusion. Contrast computed tomography revealed a large solitary spherical-to-cylindrical tumor in the caudal mediastinum with variably thick, contrast-enhancing walls with lobular to frond-like proliferations that arose circumferentially and projected internally into a single, variably sized, fluid-attenuating lumen. The wall and lumen corresponded to the serous membrane and serous cavity of the MSC. Surgical exploration confirmed that both tumors arose from the mediastinum. Both had similar histologic findings, and special stains were necessary for definitive diagnosis. The tumor was nonresectable in one dog, and it was euthanized intraoperatively. The other survived 7 mo. An MSC mesothelioma should be considered a possible cause of hemothorax in dogs that may be detected on thoracic radiography and computed tomography. Differential diagnoses include esophageal foreign body or neoplasm, paraesophageal diaphragmatic hernia, MCS empyema, and pulmonary adenocarcinoma, with thoracic computed tomography helping to rule out foreign body and diaphragmatic hernia. For confirmed neoplasms, histochemistry and immunohistochemistry should be performed to differentiate between mesothelioma and pulmonary adenocarcinoma.

Cytological Diagnostic Procedures in Malignant Mesothelioma

Malignant mesotheliomas (MM) are rare tumors with high mortality rates, whose incidence varies regionally and nationally, and the diagnosis is difficult. Histology-based diagnosis is considered the gold standard despite its low sensitivity of 57-84%. However, recent advances in cytological analysis offer promise for diagnostic advancements. In this study, we reappraised the current cytological guidelines for the MM diagnosis and concluded on their practicability and reliability. The study included 5731 consecutive specimens of pleural effusions from 4552 patients (3026 males of the average age of 67.5 years and 1526 females of the average age of 65.4 years) between December 2017 and January 2000. Out of these patients, 444 (9.8%) were diagnosed with MM. The effusions were examined by immunocytochemistry using routine Giemsa staining. Additionally, hyaluronic acid (HA) was assessed. Cytological findings confirmed 223 out of the 444 MM. The additional 88 cases with negative cytology were corroborated by supplemental assessments of HA above 30 mg/L. Cytological evaluation accomplished the sensitivity of 0.50, specificity of 0.99, and a positive predictive value (PPV) of 0.97 for MM diagnosis. The use of HA determination raised the sensitivity to 0.70 without affecting the specificity or PPV. We conclude that cytological evaluation of effusions aided by the assessment of HA demonstrates the diagnostic sensitivity and specificity for MM no less than the hitherto standard histological evaluation. The cytology-based MM diagnosis may thus be routinely considered when MM is suspected and may offer confirmatory advantages in difficult or doubtful diagnostic cases.

The cell of cancer origin provides the most reliable roadmap to its diagnosis, prognosis (biology) and therapy

Cancers arise from single transformed cells from virtually every organ of the body, divide in a relatively uncontrolled manner, and metastasize widely. A search for a "magic bullet" to precisely diagnose, characterize, and ultimately treat cancer has largely failed because cancer cells do not differ significantly from their organ-specific cells of origin. Instead of searching for genomic, epigenetic, transcriptional, and translational differences between cancers and their cells of origin, we should paradoxically focus on what cancer cells have in common with their untransformed cells of origin. This redirected search will lead to improved diagnostic and therapeutic strategies where therapeutic index considerations and drug-limiting toxicities can largely be circumvented. We cite three cancer examples that illustrate this paradigm-shifting strategy: pseudomyxoma peritonei (PP), metastasis of unknown origin (cancers of unknown primary) (MUO), and cancers that arise from potentially dispensable organs (CAD). In each of these examples, the cell of cancer origin still provides the most reliable road map to its diagnosis, prognosis (biology), and therapy.

Primary Ovarian Mesothelioma: A Case Series with Electron Microscopy Examination and Review of the Literature

Primary ovarian mesothelioma is a rare, aggressive neoplastic disease with a poor prognosis. At onset, the tumor is only rarely limited to the ovaries and usually already widespread in the peritoneum. The rarity of this entity and the difficulties differentiating it from either ovarian carcinoma or peritoneal mesothelioma may lead to frequent misdiagnoses and may raise some concerns about its histogenesis. Thus, reporting such rare cases is fundamental to gain greater awareness of this neoplasm and try to answer unsolved questions. Herein, we described four cases of histological diagnoses of ovarian mesothelioma extrapolated by the regional mesothelioma register of Apulia (southern Italy). In all cases, a detailed medical history was collected according to national mesothelioma register guidelines. A broad panel of antibodies was used for immunohistochemistry to confirm the diagnoses. Moreover, ovarian tissue samples were also examined by transmission and scanning electron microscopy, detecting asbestos fibers and talc crystals in two cases. Because of the few cases described, we reviewed the English literature in the Medline database, focusing on articles about ovarian mesothelioma "misclassification", "misdiagnosis", "diagnostic challenge" or "diagnostic pitfall" and on unsolved questions about its histogenesis and possible risk factors.

Immunochemistry in the work-up of mesothelioma and its differential diagnosis and mimickers

The differential diagnosis in cellular effusions with cytological atypia often includes malignant mesothelioma (MM), reactive mesothelial proliferation, and malignancies of metastatic origin, particularly carcinomas. The International Reporting System for Serous Fluid recently established guidelines for reporting MM. In conjunction with the cytomorphologic evaluation, the role of immunochemistry (IC) was emphasized as a very useful tool in the workup of serous fluids, especially with the availability of novel markers. Utilizing a panel of markers, IC allows the characterization of the cells, whether mesothelial or not, and when mesothelial origin is established, IC can frequently assist in delineating its benign or malignant nature. IC can also confirm metastatic disease, allowing the identification of the primary origin in most cases. This review summarizes the current status of IC and its role in the diagnosis of MM and its differential diagnosis in serous fluids.

Distant cutaneous metastasis of malignant epithelioid mesothelioma

Malignant mesothelioma is a locally aggressive malignancy most commonly arising from the pleural and/or peritoneal cavity. Distant cutaneous metastasis is extremely rare. Here, we describe two cases of mesothelioma metastatic to the head and neck skin. Case 1: A 64-year-old man diagnosed previously with extensive thoracic and abdominal mesothelioma, developed a rapidly growing right upper lip lesion, for which a wedge resection was performed. Case 2: A 77-year-old woman with a history of pleural mesothelioma developed a firm, mobile subcutaneous nodule on the right lateral forehead, clinically thought to represent either an epidermal inclusion cyst or a lipoma. A punch biopsy was performed. In both cases, histopathologic evaluation revealed dermal proliferation of epithelioid cells with moderate cytologic atypia and three mitotic figures per mm² and two mitotic figures per mm² for Cases 1 and 2, respectively. Immunohistochemical studies revealed the lesional cells to be positive for WT1, mesothelin, D2-40, CK5/6, while being negative for melanocytic and other keratinocytic markers, supporting a diagnosis of metastatic mesothelioma. Awareness of rare instances of cutaneous metastases from malignant mesothelioma is necessary to avoid possible misdiagnosis and ensure appropriate management.

P53-regulated miR-320a targets PDL1 and is downregulated in malignant mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer, related to asbestos exposure, which has a dismal prognosis. MPM diagnosis is late and often challenging, suggesting the need to identify more reliable molecular biomarkers. Here, we set out to identify differentially expressed miRNAs in epithelioid, biphasic, and sarcomatoid MPMs versus normal mesothelium and explored specific miRNA contribution to mesothelial tumorigenesis. We screened an LNA™-based miRNA-microrray with 14 formalin-fixed paraffin-embedded (FFPE) MPMs and 6 normal controls. Through real-time qRT-PCR we extended the analysis of a miRNA subset and further investigated miR-320a role through state-of-the-art techniques. We identified 16 upregulated and 32 downregulated miRNAs in MPMs versus normal tissue, including the previously identified potential biomarkers miR-21, miR-126, miR-143, miR-145. We showed in an extended series that miR-145, miR-10b, and miR-320a levels can discriminate tumor versus controls with high specificity and sensitivity. We focused on miR-320a because other family members were found downregulated in MPMs. However, stable miR-320a ectopic expression induced higher proliferation and migration ability, whereas miR-320a silencing reduced these processes, not supporting a classic tumor-suppressor role in MPM cell lines. Among putative targets, we found that miR-320a binds the 3'-UTR of the immune inhibitory receptor ligand PDL1 and, consistently, miR-320a modulation affects PDL1 levels in MPM cells. Finally, we showed that p53 over-expression induces the upregulation of miR-320a, along with miR-200a and miR-34a, both known to target PDL1, and reduces PDL1 levels in MPM cells. Our data suggest that PDL1 expression might be due to a defective p53-regulated miRNA response, which could contribute to MPM immune evasion or tumorigenesis through tumor-intrinsic roles.

Malignant mesothelioma metastatic to the oral region and latest topics (Review)

Malignant mesothelioma (MM) is a rare neoplasm with poor prognosis that usually develops after exposure to asbestos, and is characterised by aggressive local invasion and metastatic spread. While metastasis to the oral cavity is very rare, a total of 23 cases of MM metastasising to the oral cavity were identifed. Among those, the tongue was the most common site of metastasis (39.1%), and frequently involved the epithelioid MM cell type. Recent studies have elucidated the mechanisms underlying the development of MM. Chronic inflammation has been implicated in promoting MM growth and was shown to play a key role by driving the release of high mobility group box protein 1 following asbestos deposition. Inherited heterozygous germline mutations in the deubiquitylase BRCA-associated protein 1 were shown to increase the incidence of MM in some families. Infection by the simian virus 40 was also found to be associated with the occurrence of MM. Moreover, the increasing incidence rates of MM, together with its propensity to metastasise to the oral cavity, indicate that clinicians and pathologists should be highly aware of this disease. Furthermore, identification of novel serum biomarkers would enable better screening and treatment of MM, and improve the survival outcomes.

Multicystic and diffuse malignant peritoneal mesothelioma in children

BACKGROUND

Malignant and multicystic peritoneal mesotheliomas are extremely rare tumors in children, developing from mesothelial cells. No specific guidelines are available at this age.

METHODS

We performed a retrospective analysis of all identified children (< 18-year-old) treated in France from 1987 to 2017 for a diffuse malignant peritoneal mesothelioma (DMPM) or a multicystic peritoneal mesothelioma (MCPM).

RESULTS

Fourteen patients (5 males and nine females), aged 2.2 to 17.5 years, were included. The most frequent presenting symptoms were abdominal pain, ascitis, and alteration in the general condition. Eight patients had epithelioid mesothelioma, three had biphasic mesothelioma, and three had MCPM. Eight patients with DMPM diagnosis received cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Among them, six patients had neoadjuvant systemic chemotherapy, one patient, post-operative chemotherapy, and one patient CRS and HIPEC only. Three patients received only systemic chemotherapy. All patients with MCPM had only surgery. After a median follow-up of seven years (2-15), six patients (6/11; one death) with DMPM and two patients (two/three) with MCPM had a local and distant recurrences.

CONCLUSION

Peritoneal mesothelioma in children is a rare condition with difficult diagnosis and high risk of recurrence. Worldwide interdisciplinary collaboration and networking are mandatory to help diagnosis and provide harmonious treatment guidelines.

Update on the pathologic diagnosis of malignant mesothelioma

Malignant mesothelioma is an uncommon tumor that may be difficult to diagnose. The International Mesothelioma Interest Group has been writing guidelines for pathological diagnosis that are periodically updated. The guidelines are being updated based on published literature in the last 3 years, and experience of more than 20 leading international pathologists in the field who will be co-authors. Updates were discussed by attendees of the Pulmonary Pathology Society Biennial Meeting (Dubrovnik, Croatia, June 2019). Areas with significant advancements/changes include utilization of immunohistochemistry (establishing mesothelial lineage and benign versus malignant), prognosis and nuclear grading, biphasic malignant mesothelioma, transitional pattern, malignant mesothelioma in situ, and therapeutic/molecular targets.

Clinical and surgical outcomes of patients with peritoneal mesothelioma discussed at a monthly national multidisciplinary team video-conference meeting

Background

Peritoneal mesothelioma (PM) is a rare primary neoplasm of the peritoneum with an increasing incidence worldwide. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has shown promise as a treatment strategy. A national PM multidisciplinary team (national PM MDT) video‐conference meeting was established in the UK and Ireland in March 2016, aiming to plan optimal treatment, record outcomes and provide evidence for the benefits of centralization. This article reports on the activities and outcomes of the first 2·5 years.

Methods

Between March 2016 and December 2018, patients with PM, referred to peritoneal malignancy centres in Basingstoke, Birmingham, Manchester and Dublin, were discussed by the national PM MDT via video‐conference. The MDT was composed of surgeons, radiologists, specialist nurses and pathologists. Patients were considered for CRS and HIPEC if considered fit for surgery and if radiological imaging suggested that complete surgical cytoreduction could be achieved. Morbidity and mortality following surgery were analysed. Survival analysis following MDT discussion was conducted.

Results

A total of 155 patients (M : F ratio 0·96) with a mean(s.d.) age of 57(17) years were discussed. To date, 22 (14·2 per cent) have had CRS and HIPEC; the median Peritoneal Cancer Index for the surgical group was 17·0. Complete cytoreduction was achieved in 19 patients. Clavien–Dindo grade I–II complications occurred in 16 patients; there was no grade III–IV morbidity or 30‐day in‐hospital mortality. The median follow‐up for the whole cohort was 18·7 months, and the 2‐year survival rate from time of first review at the national PM MDT was 68·3 per cent.

Conclusion

The centralized national PM MDT was effective at selecting patients suitable for CRS and HIPEC, reporting a good outcome from patient selection.

Clinical feature of diagnostic challenging cases for pleural biopsy in patient with malignant pleural mesothelioma

OBJECTIVE

Pleural biopsy through video-assisted thoracic surgery (VATS pleural biopsy) is the most reliable diagnostic procedure for malignant pleural mesothelioma (MPM). However, definitive diagnosis of MPM is occasionally difficult to establish. This study aims to investigate clinicopathological features of MPM patients who failed diagnosis by the first VATS pleural biopsy.

METHODS

Four hundred consecutive patients with suspected MPM who received VATS pleural biopsy between March 2004 and July 2017 were enrolled in this retrospective study. Patients, whose histological diagnoses were not definitive in the first VATS pleural biopsy, were followed up as atypical mesothelial proliferation (AMP) or non-specific pleuritis (NSP). Re-examination was performed in cases strongly suspected of having MPM.

RESULTS

Of the 400 patients, 267 (66.8%) were pathologically diagnosed with MPM, 25 with metastatic carcinoma and 6 with benign pleural disease by the first VATS pleural biopsy. Of the remaining 102 patients diagnosed with AMP or NSP, 10 patients (9.8%) were subsequently diagnosed with MPM. Analysis of the clinical course revealed that only insufficient tissue for diagnosis was obtained via VATS pleural biopsy in all cases and that it was caused by very early stage without visible tumour in 4 patients, intrathoracic inflammation in 4 and desmoplastic MPM in 2.

CONCLUSIONS

In our review, 9.8% of patients diagnosed with AMP or NSP in first VATS pleural biopsy were subsequently diagnosed with MPM due to insufficient tissue for diagnosis. Definitive diagnosis via VATS pleural biopsy is sometimes challenging in following situation; very early stage, intrathoracic inflammation and desmoplastic MPM.

Position Paper on Asbestos of the Italian Society of Occupational Medicine

The Position Paper (PP) on asbestos of the Italian Society of Occupational Medicine (SIML) aims at providing a tool to the occupational physician to address current diagnostic criteria and results of epidemiological studies, and their consequences in terms of preventive and evaluation actions for insurance, compensation and litigation. The PP was based on an extensive review of the scientific literature and was compiled by a Working Group comprising researchers who have contributed to the international literature on asbestos-related diseases, as well as occupational physicians with extensive experience in the evaluation of risks and the medical surveillance of workers currently and formerly exposed to asbestos. The PP was drafted and reviewed between 2017 and 2018; its final version was prepared according to the guidelines of AGREE Reporting Checklist. All the members of the Working Group subscribed to the document, which was eventually approved by SIML's Executive Committee. The first section addresses industrial hygiene issues, such as methods for environmental monitoring, advantages and limitations of different microscopy techniques, the potential role of microfibers and approaches for retrospective assessment of exposure, in particular in epidemiological studies. The second section reviews the biological effects of asbestos with particular attention to the diagnostic aspects of asbestosis, pleural changes, mesothelioma and lung cancer. In the following section the criteria of causal attribution are discussed, together with different hypotheses on the form of the risk functions, with a comparison of the opinions prevalent in the literature. In particular, the models of the risk function for mesothelioma were examined, in the light of the hypothesis of an acceleration or anticipation of the events in relation to the dose. The last section discusses topics of immediate relevance for the occupational physician, such as health surveillance of former exposed and of workers currently exposed in remediation activities.

Modulation of Calretinin Expression in Human Mesothelioma Cells Reveals the Implication of the FAK and Wnt Signaling Pathways in Conferring Chemoresistance towards Cisplatin

Malignant mesothelioma (MM) is an aggressive asbestos-linked neoplasm, characterized by dysregulation of signaling pathways. Due to intrinsic or acquired chemoresistance, MM treatment options remain limited. Calretinin is a Ca²⁺-binding protein expressed during MM tumorigenesis that activates the FAK signaling pathway, promoting invasion and epithelial-to-mesenchymal transition. Constitutive calretinin downregulation decreases MM cells’ growth and survival, and impairs tumor formation in vivo. In order to evaluate early molecular events occurring during calretinin downregulation, we generated a tightly controlled IPTG-inducible expression system to modulate calretinin levels in vitro. Calretinin downregulation significantly reduced viability and proliferation of MM cells, attenuated FAK signaling and reduced the invasive phenotype of surviving cells. Importantly, surviving cells showed a higher resistance to cisplatin due to increased Wnt signaling. This resistance was abrogated by the Wnt signaling pathway inhibitor 3289-8625. In various MM cell lines and regardless of calretinin expression levels, blocking of FAK signaling activated the Wnt signaling pathway and vice versa. Thus, blocking both pathways had the strongest impact on MM cell proliferation and survival. Chemoresistance mechanisms in MM cells have resulted in a failure of single-agent therapies. Targeting of multiple components of key signaling pathways, including Wnt signaling, might be the future method-of-choice to treat MM.

Liquid Biopsy in Malignant Pleural Mesothelioma: State of the Art, Pitfalls, and Perspectives

Malignant pleural mesothelioma (MPM) is an aggressive tumor linked to asbestos exposure. Although the risk factors for MPM are well-known, the majority of MPM patients are diagnosed at an advanced stage and have a very poor prognosis. Circulating biomarkers for early diagnosis remain to be identified, and the current standard for MPM diagnosis relies on pleural biopsies. Robust non-invasive tests for the screening of asbestos-exposed subjects are therefore an important unmet clinical need. This review provides a critical summary of recent liquid biopsy-based studies aimed at discovering novel blood-based circulating biomarkers for the early diagnosis and prognostic stratification of MPM patients.

Malignant mesothelioma: A histomorphological and immunohistochemical study of 24 cases from a tertiary care hospital in Southern India

BACKGROUND

Malignant mesotheliomas are histologically heterogeneous neoplasms. Definite diagnosis requires a varied panel of immunohistochemical (IHC) markers to differentiate these from histological mimics. Only a few case series have been reported in the Indian literature where mesotheliomas have been analyzed on routine histology and IHC.

AIM

To evaluate the histological features of malignant mesothelioma and to elucidate the best possible immunomarker combination useful in different scenarios.

MATERIALS AND METHODS

A total of 24 cases of malignant mesotheliomas of different sites encountered over a 6-year period were retrospectively analyzed with regard to their histomorphology and IHC findings.

RESULTS

The pleura was the most common site of involvement (16 cases) followed by peritoneum (5 cases) and pericardium (3 cases). Epithelioid mesothelioma was the most common histological type (15 cases, 62.5%) followed by sarcomatoid (5 cases, 20.84%), deciduoid (2 cases, 8.34%), and 1 case each of desmoplastic and biphasic mesothelioma. Among the mesothelial markers, WT1 was positive in 17 of 20 (85%) cases and calretinin was positive in 20 of 21 (95.23%) cases. D2-40 and CK5/6 were positive in all cases where they were studied. Adenocarcinoma markers TTF-1, napsin A, and CEA had very high negative predictive value in ruling out mesothelioma.

CONCLUSION

The differential diagnosis of mesotheliomas varies with histological type and tumor location. Judicious use of various combinations of IHC markers in different situation has been highlighted in this article.

MicroRNAs for the Diagnosis and Management of Malignant Pleural Mesothelioma: A Literature Review

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor with a variable incidence among different countries. Occupational asbestos exposure is the most important etiological factor and a very long latency period is widely reported. In the early phase of the disease, clinical signs are absent or not specific. For this reason, the diagnosis is frequently achieved only in the advanced stages. The histopathological diagnosis per se is also very complex, and no known factor can predict the prognosis with certainty. Nonetheless, current survival rates remain very low, despite the use of standard treatments, which include surgery, chemotherapy and radiotherapy. The identification of new prognostic and/or diagnostic biomarkers, and the discovery of therapeutic targets is a priority and could lead to a real significant impact on the management of malignant pleural mesothelioma. In this scenario, the role of microRNAs is becoming increasingly relevant, with the promise of a quick translation in the current clinical practice. Despite the relative novelty of this field, the number of works and candidate microRNAs that are present in literature is striking. Unfortunately, to date the microRNAs with the most clinical relevance for MPM are still matter of debate, probably due to the variety of approaches, techniques, and collected samples. Although specific microRNAs (e.g., let-7, miR-15 and miR-16, miR-21, miR-34a, and the miR-200 family) have been reported several times from different groups, the heterogeneity of published data reinforces the need of more comprehensive and unified studies on this topic. In this review we collect and discuss the studies focused on the involvement of microRNAs in different aspects of MPM, from their biological role in tumorigenesis and progression, to their possible application as diagnostic, prognostic and predictive biomarkers. Lastly, we examine their potential value as for the design of therapeutic approaches that could benefit MPM patients.

[Malignant pleural mesothelioma: The role of surgery]

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive disease, whose incidence is increasing. Asbestos is the primary causal agent.

STATE OF KNOWLEDGE

Knowledge about MPM has evolved. Thoracoscopy is essential for diagnosis of MPM. It allows performing pleural biopsies, to study the extent of the disease and to relieve dyspnea. The pathological diagnosis is also better codified with immunohistochemistry and with analysis by expert of Mesopath group. Curative surgical treatments are pleurectomy decortication and extended pneumonectomy in combination with chemotherapy and/or radiotherapy. Those heavy treatments improve survival in highly selected patients. For the other patients, supportive measures will be considered to reduce pain and dyspnea.

PROSPECT

Radical surgical treatment is only offered in therapeutic trials or multimodal treatment. Its place is not formally established. New therapies associated to surgical treatment are being studied.

CONCLUSIONS

Surgical management of MPM has to be operated in specialized teams where the survival benefit and quality of life is discussed case by case.

Sarcomatoid carcinoma of the pancreas: A case report and review of the literature

Sarcomatoid carcinoma (SC) is an extremely rare and complicated malignant neoplasm that consists of both malignant epithelial components and atypical spindle cells that express an epithelial phenotype. The presents study reported a case of SC of the pancreas (SCP), along with a brief review of the literature. A 63‑year‑old man was admitted to The Second Hospital of Jilin University hospital with complaints of epigastralgia and jaundice of one month in duration. Based on preoperative laboratory blood tests and radiography, a mass at the distal common bile duct was suspected. Intraoperative examination discovered a 2.5x2x1.8‑cm mass in the pancreatic head, with invasion of the distal bile duct. Pancreaticoduodectomy was performed. Histopathology and immunohistochemistry of the specimen confirmed the diagnosis of SCP. The patient succumbed 18 months after surgery due to multiple hepatic metastases.

Glypican-1 immunohistochemistry does not separate mesothelioma from pulmonary adenocarcinoma

Immunohistochemistry (IHC) is used to help differentiate pleural mesothelioma from pulmonary adenocarcinoma in pleural biopsies and cytology specimens of pleural effusions due to overlapping morphologic features between these two malignancies. The aim of this study is to evaluate IHC glypican-1, a recently proposed marker for epithelioid mesothelioma, in our cohort of mesotheliomas and pulmonary adenocarcinoma. Tissue microarrays with duplicate cores from 33 cases of mesotheliomas (28 epithelioid type and five sarcomatoid type) and 21 cases of pulmonary adenocarcinoma were stained with glypican-1 antibody. The proportion of cases by tumor type showing staining with glypican-1 and the H-score for each tumor type were evaluated. All 33 cases of mesothelioma and all 20 cases of pulmonary adenocarcinoma with interpretable cores showed positive cytoplasmic staining. All but one case of mesothelioma and all pulmonary adenocarcinomas showed staining in at least 80% of the tumor cells. The mean H-score for glypican-1 of mesothelioma (134 ± 59, mean ± SD) was not significantly different from that for pulmonary adenocarcinoma (156 ± 60; P = 0.21). Neither epithelioid type (mean H-score 135 ± 57) nor sarcomatoid type (mean H-score 130 ± 78) of mesothelioma showed different H-scores when compared to pulmonary adenocarcinoma (P = 0.23 and 0.42, respectively). In conclusion, glypican-1 IHC does not differentiate mesothelioma from pulmonary adenocarcinoma.

Genomics and Epigenetics of Malignant Mesothelioma

Malignant mesothelioma is an aggressive and lethal asbestos-related disease. Diagnosis of malignant mesothelioma is particularly challenging and is further complicated by the lack of disease subtype-specific markers. As a result, it is especially difficult to distinguish malignant mesothelioma from benign reactive mesothelial proliferations or reactive fibrosis. Additionally, mesothelioma diagnoses can be confounded by other anatomically related tumors that can invade the pleural or peritoneal cavities, collectively resulting in delayed diagnoses and greatly affecting patient management. High-throughput analyses have uncovered key genomic and epigenomic alterations driving malignant mesothelioma. These molecular features have the potential to better our understanding of malignant mesothelioma biology as well as to improve disease diagnosis and patient prognosis. Genomic approaches have been instrumental in identifying molecular events frequently occurring in mesothelioma. As such, we review the discoveries made using high-throughput technologies, including novel insights obtained from the analysis of the non-coding transcriptome, and the clinical potential of these genetic and epigenetic findings in mesothelioma. Furthermore, we aim to highlight the potential of these technologies in the future clinical applications of the novel molecular features in malignant mesothelioma.

On the diagnosis of malignant pleural mesothelioma: A necropsy-based study of 171 cases (1997–2016)

Background:

Malignant pleural mesothelioma (MPM) diagnosis is known to be difficult. We report on the diagnostic elements available in life in an MPM necropsy case series and describe the frequency of non-neoplastic asbestos-related diseases as biological exposure indices.

Methods:

We reviewed pathologic and clinical records of an unselected series of autopsies (1977–2016) in patients with MPM employed in the Monfalcone shipyards or living with shipyard workers. We assessed the consistency with autopsy results of diagnoses based on, respectively, radiologic, cytologic, and histologic findings, with and without immunophenotyping.

Results:

Data on 171 cases were available: for 169, autopsy confirmed the MPM diagnosis. In life, 119 cases had histologic confirmation of diagnosis, whereas 7 were negative; all cases without immunophenotypization were autoptic MPMs. Cytology alone had been positive in 18 autoptic MPM cases, negative in 14. Radiologic imaging alone had been positive in another 16, negative in 11. In the 2 cases not confirmed at autopsy, MPM had been suspected by chest computed tomography only. Bilateral pleural plaques were found in 144 and histologic evidence of asbestosis in 62 cases.

Conclusions:

Autopsies confirmed 169/171 cases, including cases that would not be considered as certain based on diagnosis in life. Radiologic imaging, cytologic examination of pleural effusions, or both combined had low sensitivity but high positive predictive value: when they are positive, proceeding to thoracoscopy should be justified. MPM has been correctly diagnosed even without immunohistochemistry. The prevalence of pleural plaques and asbestosis was high due to severity of asbestos exposures in these cases.

Immunohistochemistry for Diagnosis of Metastatic Carcinomas of Unknown Primary Site

Immunohistochemistry has become an essential ancillary examination for the identification and classification of carcinomas of unknown primary site (CUPs). Over the last decade, the diagnostic accuracy of organ- or tumour-specific immunomarkers and the clinical validation of effective immunohistochemical panels has improved significantly. When dealing with small sample sizes, diagnostic accuracy is crucial, particularly in the current era of targeted molecular and immune-based therapies. Effective systematic use of appropriate immunohistochemical panels enables accurate classification of most of the undifferentiated carcinomas as well as careful preservation of tissues for potential molecular or other ancillary tests. This review discusses the algorithmic approach to the diagnosis of CUPs using CK7 and CK20 staining patterns. It outlines the most frequently used tissue-specific antibodies, provides some pitfalls essential in avoiding potential diagnostic errors and discusses the complementary tools, such as molecular tumour profiling and mutation-specific antibodies, for the improvement of diagnosis and prediction of the treatment response.

New Perspectives on Diagnosis and Therapy of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, but severe form of cancer, with an incidence that varies significantly within and among different countries around the world. It develops in about one to two persons per million of the general population, leading to thousands of deaths every year worldwide. To date, the MPM is mostly associated with occupational asbestos exposure. Asbestos represents the predominant etiological factor, with approximately 70% of cases of MPM with well-documented occupational exposure to asbestos, with the exposure time, on average greater than 40 years. Environmental exposure to asbestos is increasingly becoming recognized as a cause of mesothelioma, together with gene mutations. The possible roles of other cofactors, such as viral infection and radiation exposure, are still debated. MPM is a fatal tumor. This cancer arises during its early phase without clinical signs. Consequently, its diagnosis occurs at advanced stages. Standard clinical therapeutic approaches include surgery, chemo- and radiotherapies. Preclinical and clinical researches are making great strides in the field of this deadly disease, identifying new biomarkers and innovative therapeutic approaches. Among the newly identified markers and potential therapeutic targets, circulating microRNAs and the Notch pathway represent promising avenues that could result in the early detection of the tumor and novel therapeutic approaches.

Peritoneal and scrotal carcinomas of unknown origin in two bovine calves

Two unrelated bovine beef calves, aged 2 mo and 3 mo, were presented to The Ohio State University Veterinary Medical Center because of scrotal swelling and abdominal distension. On postmortem examination, there was abundant peritoneal fluid and numerous small friable masses covering all peritoneal surfaces and extending into the scrotum via the tunica vaginalis, with no identifiable primary neoplasm. Based on light microscopy, differential diagnoses included malignant mesothelioma and anaplastic carcinoma. Immunohistochemically, the neoplasms labeled positive for cytokeratin, and negative for vimentin and calretinin. Neoplastic cells contained periodic acid-Schiff-positive, diastase-resistant cytoplasmic granules, and lacked Alcian blue-positive, hyaluronidase-negative cytoplasmic vacuoles. Ultrastructurally, the cells had features of carcinoma, including secretory granules, and lacked typical features of mesothelioma, such as long slender microvilli. Our final diagnosis was carcinoma in both calves, despite the equivocal gross and light microscopic findings. We propose that a presumptive diagnosis of peritoneal mesothelioma in bovine calves should be avoided without corroboration by a combination of histology, histochemistry, immunohistochemistry, and, if possible, electron microscopy.

Targeting the Hippo Pathway Is a New Potential Therapeutic Modality for Malignant Mesothelioma

Malignant mesothelioma (MM) constitutes a very aggressive tumor that arises from the pleural or peritoneal cavities and is highly refractory to conventional therapies. Several key genetic alterations are associated with the development and progression of MM including mutations of the CDKN2A/ARF, NF2, and BAP1 tumor-suppressor genes. Notably, activating oncogene mutations are very rare; thus, it is difficult to develop effective inhibitors to treat MM. The NF2 gene encodes merlin, a protein that regulates multiple cell-signaling cascades including the Hippo pathway. MMs also exhibit inactivation of Hippo pathway components including LATS1/2, strongly suggesting that merlin-Hippo pathway dysregulation plays a key role in the development and progression of MM. Furthermore, Hippo pathway inactivation has been shown to result in constitutive activation of the YAP1/TAZ transcriptional coactivators, thereby conferring malignant phenotypes to mesothelial cells. Critical YAP1/TAZ target genes, including prooncogenic CCDN1 and CTGF, have also been shown to enhance the malignant phenotypes of MM cells. Together, these data indicate the Hippo pathway as a therapeutic target for the treatment of MM, and support the development of new strategies to effectively target the activation status of YAP1/TAZ as a promising therapeutic modality for this formidable disease.

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.

Positive nuclear BAP1 immunostaining helps differentiate non-small cell lung carcinomas from malignant mesothelioma

The differential diagnosis between pleural malignant mesothelioma (MM) and lung cancer is often challenging. Immunohistochemical (IHC) stains used to distinguish these malignancies include markers that are most often positive in MM and less frequently positive in carcinomas, and vice versa. However, in about 10-20% of the cases, the IHC results can be confusing and inconclusive, and novel markers are sought to increase the diagnostic accuracy.We stained 45 non-small cell lung cancer samples (32 adenocarcinomas and 13 squamous cell carcinomas) with a monoclonal antibody for BRCA1-associated protein 1 (BAP1) and also with an IHC panel we routinely use to help differentiate MM from carcinomas, which include, calretinin, Wilms Tumor 1, cytokeratin 5, podoplanin D2-40, pankeratin CAM5.2, thyroid transcription factor 1, Napsin-A, and p63. Nuclear BAP1 expression was also analyzed in 35 MM biopsies. All 45 non-small cell lung cancer biopsies stained positive for nuclear BAP1, whereas 22/35 (63%) MM biopsies lacked nuclear BAP1 staining, consistent with previous data. Lack of BAP1 nuclear staining was associated with MM (two-tailed Fisher's Exact Test, P = 5.4 x 10-11). Focal BAP1 staining was observed in a subset of samples, suggesting polyclonality. Diagnostic accuracy of other classical IHC markers was in agreement with previous studies. Our study indicated that absence of nuclear BAP1 stain helps differentiate MM from lung carcinomas. We suggest that BAP1 staining should be added to the IHC panel that is currently used to distinguish these malignancies.

Capture of mesothelioma cells with 'universal' CTC-chip

Malignant mesothelioma (MM) is a highly aggressive malignant tumor, predominantly associated with job-related exposure to asbestos. Development of effective and non-invasive modalities for diagnosis is an important issue in occupational medicine. Circulating tumor cells (CTCs), which are tumor cells that are shed from primary tumors and circulate in the peripheral blood, may be detected at an earlier stage than malignant tumors, and detection of CTCs may provide a novel insight into the diagnosis of MM. In a previous study evaluating clinical utility of CTCs, detected with a widely used system 'CellSearch', the authors indicated a significant however insufficient capability in the diagnosis of MM, suggesting need for a more sensitive system. Accordingly, the authors developed a novel microfluidic system to capture CTCs (CTC-chip), and demonstrated that the CTC-chip effectively captured MM cells (ACC-MESO-4) spiked in the blood by conjugating an anti-podoplanin antibody. The results of the present study demonstrated that the CTC-chip coated with the anti-podoplanin antibody captured another MM cell (ACC-MESO-1). However, the capture efficiencies were lower than those for ACC-MESO-4. In addition, an anti-mesothelin antibody was used to capture CTCs, however the CTC-chip coated with the anti-mesothelin antibody failed to effectively capture MM cells, possibly due to low mesothelin expression. Overall, the CTC-chip may capture specific types of CTCs by conjugating any antibody against an antigen expressed on CTCs, and may be a useful system for the diagnosis of malignant tumors, including MM.

Complement Protein C1q Binds to Hyaluronic Acid in the Malignant Pleural Mesothelioma Microenvironment and Promotes Tumor Growth

C1q is the first recognition subcomponent of the complement classical pathway, which acts toward the clearance of pathogens and apoptotic cells. C1q is also known to modulate a range of functions of immune and non-immune cells, and has been shown to be involved in placental development and sensorial synaptic pruning. We have recently shown that C1q can promote tumor by encouraging their adhesion, migration, and proliferation in addition to angiogenesis and metastasis. In this study, we have examined the role of human C1q in the microenvironment of malignant pleural mesothelioma (MPM), a rare form of cancer commonly associated with exposure to asbestos. We found that C1q was highly expressed in all MPM histotypes, particularly in epithelioid rather than in sarcomatoid histotype. C1q avidly bound high and low molecular weight hyaluronic acid (HA) via its globular domain. C1q bound to HA was able to induce adhesion and proliferation of mesothelioma cells (MES) via enhancement of ERK1/2, SAPK/JNK, and p38 phosphorylation; however, it did not activate the complement cascade. Consistent with the modular organization of the globular domain, we demonstrated that C1q may bind to HA through ghA module, whereas it may interact with human MES through the ghC. In conclusion, C1q highly expressed in MPM binds to HA and enhances the tumor growth promoting cell adhesion and proliferation. These data can help develop novel diagnostic markers and molecular targets for MPM.

A review of bevacizumab in the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer with poor prognosis. Systemic chemotherapy is the primary treatment modality for the majority of patients. VEGF plays a key mitogen for MPM cells physiopathology. Bevacizumab, a monoclonal anti-VEGF antibody, was a rational approach to be tested in MPM. Based on the results of the Phase III IFCT-0701 mesothelioma avastin cisplatin pemetrexed study, cisplatin-pemetrexed-bevacizumab is now the accepted standard in France. The National Comprehensive Cancer Network guidelines have also included this combination as an option for standard front-line therapy. This review summarized the efficacy and safety data of bevacizumab in the treatment of patients with MPM.

Malignant Deciduoid Mesothelioma: case presentation of an exceptional variant and review of the literature

BACKGROUND

Malignant Deciduoid Mesothelioma (MDM) is an extremely rare variant of epithelioid mesothelioma. It was first described in young females, in the peritoneum, and its relation with asbestos was not well defined. Later reports, have shown that this variant may also occur in the pleura, the pericardium and the tunica vaginalis of elderly people, who had been exposed to asbestos.

CASE PRESENTATION

We report a case of malignant deciduoid mesothelioma that occurred in the peritoneal cavity, and the omentum of a 35-year-old woman. The patient had never been exposed to asbestos.

CONCLUSIONS

Through this observation, we describe clinical, histopathological, and immunohistochemical findings of deciduoid mesothelioma, and review the literature reports.

Guidelines for Pathologic Diagnosis of Malignant Mesothelioma 2017 Update of the Consensus Statement From the International Mesothelioma Interest Group

CONTEXT

- Malignant mesothelioma (MM) is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE

- To provide updated, practical guidelines for the pathologic diagnosis of MM.

DATA SOURCES

- Pathologists involved in the International Mesothelioma Interest Group and others with an interest and expertise in the field contributed to this update. Reference material included up-to-date, peer-reviewed publications and textbooks.

CONCLUSIONS

- There was discussion and consensus opinion regarding guidelines for (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) recognition of the key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiating epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas, and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid MM, (7) use of molecular markers in the diagnosis of MM, (8) electron microscopy in the diagnosis of MM, and (9) some caveats and pitfalls in the diagnosis of MM. Immunohistochemical panels are integral to the diagnosis of MM, but the exact makeup of panels employed is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Depending on the morphology, immunohistochemical panels should contain both positive and negative markers for mesothelial differentiation and for lesions considered in the differential diagnosis. Immunohistochemical markers should have either sensitivity or specificity greater than 80% for the lesions in question. Interpretation of positivity generally should take into account the localization of the stain (eg, nuclear versus cytoplasmic) and the percentage of cells staining (>10% is suggested for cytoplasmic and membranous markers). Selected molecular markers are now being used to distinguish benign from malignant mesothelial proliferations. These guidelines are meant to be a practical diagnostic reference for the pathologist; however, some new pathologic predictors of prognosis and response to therapy are also included.

A case of malignant peritoneal mesothelioma suggesting the utility of combining double-contrast radiography and endoscopy with computed tomography for diagnosis

A 68-year-old woman presented with abdominal pain, weight loss, and vomiting. Enhanced computed tomography (CT) showed slightly increased density in the mesentery and edema of the third portion of the duodenum and proximal jejunum. Little ascites, but no primary lesion, lymph node metastases, or distant metastases, were observed. Endoscopic findings included erythema and edema in the distal duodenum and proximal jejunum without epithelial lesions. Double-contrast radiography revealed transverse ridging with convergence, suggesting a serosal lesion. We suspected disease involving the serosa, such as mesenteric panniculitis. However, the lesion was definitively diagnosed as malignant peritoneal mesothelioma based on a biopsy specimen obtained at laparotomy. The combination of transverse ridging with convergence on double-contrast radiography and mucosal edema without epithelial lesions on endoscopy was consistent with a disorder involving the serosa. Transverse ridging with convergence is helpful to diagnose serosal pathology such as malignant peritoneal mesothelioma. Combining the findings of double-contrast radiography and endoscopy with computed tomography may facilitate diagnosis of malignant peritoneal mesothelioma. Thus, in case of increased density of mesentery and wall thickness on CT image with transverse ridging with convergence on double-contrast radiography and without epithelial lesion on endoscopy, malignant peritoneal mesothelioma must be considered.