What are the current best immunohistochemical markers for the diagnosis of epithelioid mesothelioma? A review and update

Soluble mesothelin-related peptide as a prognosticator in pleural mesothelioma patients receiving checkpoint immunotherapy

BACKGROUND

Immune checkpoint therapy (ICT) has significantly impacted the treatment of malignant pleural mesothelioma (MPM). Despite some promising results from combination therapies, nearly half of MPM patients do not benefit, underscoring the urgent need for reliable predictive biomarkers. This study assesses the prognostic value of serum soluble mesothelin-related peptide (SMRP) and PD-L1 levels in MPM patients receiving ICT.

METHODS

We conducted a retrospective analysis of 125 MPM patients treated with ICT by measuring pre-ICT serum levels of SMRP and PD-L1. We also examined the correlation of these serum levels with tumor mRNA expressions of mesothelin and PD-L1. Both univariable and multivariable Cox regression analyses were used to determine independent prognosticators for overall survival (OS). A prospective ICT clinical trial and our historical cohort were included for validation.

RESULTS

Seventy-seven patients (62%) were treated with either anti-PD-(L)1 monotherapy, and the remaining 38% received combination ICT. Higher pre-ICT SMRP levels were observed in epithelioid MPM compared to nonepithelioid MPM. Serum PD-L1 levels did not differ significantly between the different histologic groups. Univariable analysis identified durable clinical benefit, development of immune-related adverse events, and SMRP levels as significantly associated with OS. Multivariable analysis confirmed SMRP as an independent prognostic factor, with lower levels (≤1.35 nmol/L) correlating with improved OS. The association of high SMRP with worse prognosis was validated in the prospective ICT clinical trial cohort and not in our historical cohort treated without ICT.

CONCLUSIONS

SMRP is a promising serum biomarker for predicting survival in MPM patients treated with ICT and warrants prospective investigation.

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

CONTEXT.—

Immunohistochemistry has become a valuable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVE.—

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

DATA SOURCES.—

Literature review and the author's research data and personal practice experience.

CONCLUSIONS.—

This review article highlights that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoid potential diagnostic errors.

Comprehensive Review of Mesothelioma Cases: From Diagnosis to Therapeutic Strategies

Mesothelioma is a rare and aggressive malignancy typically associated with asbestos exposure. We present the clinical and diagnostic journey of a 63-year-old male carpenter, who presented with concerning symptoms of shortness of breath and total right lung "white-out" on imaging. Comprehensive medical evaluation revealed the presence of malignant pleural mesothelioma. This study underscores the importance of considering mesothelioma as a potential diagnosis in individuals with occupational asbestos exposure and highlights patterns in diagnosing and managing this devastating disease. Early recognition and intervention are essential in improving outcomes for patients diagnosed with mesothelioma.

Pleural Mesothelioma: Advances in Blood and Pleural Biomarkers

Pleural mesothelioma (PM) is a type of cancer that is highly related to exposure to asbestos fibers. It shows aggressive behavior, and the current therapeutic approaches are usually insufficient to change the poor prognosis. Moreover, apart from staging and histological classification, there are no validated predictors of its response to treatment or its long-term outcomes. Numerous studies have investigated minimally invasive biomarkers in pleural fluid or blood to aid in earlier diagnosis and prognostic assessment of PM. The most studied marker in pleural effusion is mesothelin, which exhibits good specificity but low sensitivity, especially for non-epithelioid PM. Other biomarkers found in pleural fluid include fibulin-3, hyaluronan, microRNAs, and CYFRA-21.1, which have lower diagnostic capabilities but provide prognostic information and have potential roles as therapeutic targets. Serum is the most investigated matrix for biomarkers of PM. Several serum biomarkers in PM have been studied, with mesothelin, osteopontin, and fibulin-3 being the most often tested. A soluble mesothelin-related peptide (SMRP) is the only FDA-approved biomarker in patients with suspected mesothelioma. With different serum and pleural fluid cut-offs, it provides useful information on the diagnosis, prognosis, follow-up, and response to therapy in epithelioid PM. Panels combining different markers and proteomics technologies show promise in terms of improving clinical performance in the diagnosis and monitoring of mesothelioma patients. However, there is still no evidence that early detection can improve the treatment outcomes of PM patients.

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.

Immunohistochemical characterization of mesothelioma in 6 large felids

Mesothelioma has been reported frequently in large felids. These neoplasms present a diagnostic challenge given their highly variable morphology that mimics carcinomas or sarcomas at different locations. Our goal was to characterize mesotheliomas morphologically and immunohistochemically to determine if a panel of antibodies could be used to more accurately support the diagnosis of these neoplasms in large felids. Mesotheliomas from 6 large felids, including 4 clouded leopards, 1 Bengal tiger, and 1 cheetah, were immunohistochemically labeled for vimentin, E-cadherin, pancytokeratin, Wilms tumor 1 (WT1), MUC-1, and calretinin. The mesotheliomas of the 4 clouded leopards and the tiger were of the epithelial subtype; the mesothelioma from the cheetah was biphasic. All 6 mesotheliomas had strong immunohistochemical labeling for vimentin, E-cadherin, and pancytokeratin. All cases had cytoplasmic labeling for WT1, and 2 also had nuclear labeling. The 3 mesotheliomas with distinct papillary fronds were weakly positive for MUC-1. These and one other epithelial mesothelioma were also positive for calretinin. Our study demonstrates that the morphologic and immunohistochemical phenotypes of mesothelioma that have been identified in humans and domestic species can occur in large felids, and a panel of pancytokeratin, vimentin, WT1, and calretinin can be utilized to support the diagnosis of these neoplasms.

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.

Prognostic Significance of Blood, Serum, and Ascites Parameters in Patients with Malignant Peritoneal Mesothelioma or Peritoneal Carcinomatosis

To determine effects of the biochemical and cytological properties of blood, serum, and ascites on survival of patients with malignant peritoneal effusion (MPeE), including malignant peritoneal mesothelioma (MPeM) and peritoneal carcinomatosis (PC), we conducted a retrospective study of patients with MPeE and healthy controls. Potential prognostic factors were identified as follows: age, sex, blood neutrophil-to-lymphocyte ratio (NLR), serum parameters, ascites parameters, serum-ascites albumin gradient, and the ascites-serum LDH ratio. Compared to those of the control group, serum albumin levels were significantly lower, and the NLR and serum LDH levels were significantly higher in the MPeE group. Overall survival (OS) was longer in patients with MPeM compared to that in patients with PC. Compared with patients in the MPeM, patients with PC had higher NLRs, ascites glucose levels, serum-ascites albumin gradients, and serum LDH levels. In contrast, their ascites albumin levels and ascites-serum LDH ratios were lower. Univariate analyses indicated that the NLR, serum LDH levels, ascites LDH levels, ascites coenocyte levels, and the ascites coenocyte-to-monocyte ratios affected the OS. Multivariate analyses identified only serum and ascites LDH levels as independent prognostic factors.

Overexpressed genes in malignant pleural mesothelioma: implications in clinical management

Malignant pleural mesothelioma (MPM) is a very aggressive cancer poorly responsive to current therapies. MPM patients have a very poor prognosis with a median survival of less than one year from the onset of symptoms. The biomarkers proposed so far do not lead to a sufficiently early diagnosis for a radical treatment of the disease. Thus, the finding of novel diagnostic and prognostic biomarkers and therapeutic targets is needed. Gene overexpression has been frequently associated with a malignant phenotype in several cancer types; therefore the identification of overexpressed genes may lead to the detection of novel prognostic or diagnostic marker and to the development of novel therapeutic approaches, based on their inhibition. In the last years, several overexpressed genes have been identified in MPM through gene expression profiling techniques: among them it has been found a group of 51 genes that resulted overexpressed in more than one independent study, revealing their consistency among studies. This article reviews the clinical implications of confirmed overexpressed genes in MPM described so far in literature.

Amatuximab and novel agents targeting mesothelin for solid tumors

Mesothelin (MSLN) is considered a promising target for cancer therapy. Originally extracted in 1992 after the immunization of mice with a human ovarian cancer (OC) cell line and cloned in 1996, MSLN seems to be involved in cell adhesion and metastasis. MSLN is prevalent in mesothelia tissues but is expressed in several human cancers, such as OC, pancreatic cancer, mesothelioma, and lung cancer. Amatuximab (MORAb-009) is a mouse-human chimeric monoclonal antibody with a selective affinity for MSLN. The principal mechanism of action comprises inhibition of binding of MSLN with the antigen CA125/MUC16. The highest phase of development is actually a Phase II trial (MORAb-009-201, Europe). In this review, we describe the mechanism of action of amatuximab and other MSLN-targeting novel drugs, along with a discussion about the expected efficacy, safety, and toxicity of this promising group of agents and implications for future research and clinical practice.

Calretinin as a blood-based biomarker for mesothelioma

Background

Malignant mesothelioma (MM) is a deadly cancer mainly caused by previous exposure to asbestos. With a latency period up to 50 years the incidence of MM is still increasing, even in countries that banned asbestos. Secondary prevention has been established to provide persons at risk regular health examinations. An earlier detection with tumor markers might improve therapeutic options. Previously, we have developed a new blood-based assay for the protein marker calretinin. Aim of this study was the verification of the assay in an independent study population and comparison with the established marker mesothelin.

Methods

For a case-control study in men, a total of 163 cases of pleural MM and 163 controls were available from Australia, another 36 cases and 72 controls were recruited in Germany. All controls had asbestosis and/or plaques. Calretinin and mesothelin were determined by ELISA (enzyme-linked immunosorbent assay) in serum or plasma collected prior to therapy. We estimated the performance of both markers and tested factors potentially influencing marker concentrations like age, sample storage time, and MM subtype.

Results

Calretinin was able to detect all major subtypes except for sarcomatoid MM. Calretinin showed a similar performance in Australian and German men. At a pre-defined specificity of 95% the sensitivity of calretinin reached 71% and that of mesothelin 69%, when excluding sarcomatoid MM. At 97% specificity, the combination with calretinin increased the sensitivity of mesothelin from 66% to 75%. Sample storage time did not influence the results. In controls the concentrations of calretinin increased 1.87-fold (95% CI 1.10–3.20) per 10 years of age and slightly more for mesothelin (2.28, 95% CI 1.30–4.00).

Conclusions

Calretinin could be verified as a blood-based marker for MM. The assay is robust and shows a performance that is comparable to that of mesothelin. Retrospective analyses would not be limited by storage time. The high specificity supports a combination of calretinin with other markers. Calretinin is specific for epithelioid and biphasic MM but not the rarer sarcomatoid form. Molecular markers like calretinin and mesothelin are promising tools to improve and supplement the diagnosis of MM and warrant further validation in a prospective study.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3375-5) contains supplementary material, which is available to authorized users.

Diagnosis and management options in malignant pleural effusions

Malignant pleural effusion (MPE) denotes an advanced malignant disease process. Most of the MPE are metastatic involvement of the pleura from primary malignancy at lung, breast, and other body sites apart from lymphomas. The diagnosis of MPE has been traditionally made on cytological examination of pleural fluid and/or histological examination of pleural biopsy tissue that still remains the initial approach in these cases. There has been tremendous advancement in the diagnosis of MPE now a day with techniques i.e. characteristic Ultrasound and computed tomography features, image guided biopsies, fluorodeoxyglucose-positron emission tomography imaging, thoracoscopy with direct biopsy under vision, tumor marker studies and immunocytochemical analysis etc., that have made possible an early diagnosis of MPE. The management of MPE still remains a challenge to pulmonologist and oncologist. Despite having various modalities with better tolerance such as pleurodesis and indwelling pleural catheters etc., for long-term control, all the management approaches remain palliative to improve the quality of life and reduce symptoms. While choosing an appropriate management intervention, one should consider the clinical status of the patient, life expectancy, overall cost, availability and comparative institutional outcomes, etc.

Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma

AIMS

The aims of this study were to clarify the usefulness of immunohistochemistry in the differential diagnosis of epithelioid mesothelioma with a solid growth pattern [solid epithelioid mesothelioma (SEM)] and poorly differentiated squamous cell carcinoma (PDSCC), and to confirm the validity of a specific type of antibody panel. Additionally, we aimed to clarify the pitfalls of immunohistochemical analyses.

METHODS AND RESULTS

Formalin-fixed paraffin-embedded specimens from 36 cases of SEM and 38 cases of PDSCC were immunohistochemically examined for calretinin, podoplanin (D2-40), Wilms' tumour gene product (WT1), cytokeratin (CK) 5/6, p40, p63, carcinoembryonic antigen (CEA), epithelial-related antigen (MOC31), claudin-4, thyroid transcription factor-1 (TTF-1), and napsin A. WT1 showed the highest diagnostic accuracy (85.1%) as a mesothelial marker, and CEA, p40 and claudin-4 showed higher diagnostic accuracies (95.9%, 94.6%, and 93.2%, respectively) as carcinoma markers. Calretinin (diagnostic accuracy: 75.7%), D2-40 (diagnostic accuracy: 67.6%), CK5/6 (diagnostic accuracy: 63.5%), TTF-1 (diagnostic accuracy: 55.4%) and napsin A (diagnostic accuracy: 52.7%) could not differentiate between SEM and PDSCC. Among these markers, the combination of calretinin and WT1 showed the highest diagnostic accuracy (86.5%) as a positive marker, and the combination of p40 and CEA showed the highest diagnostic accuracy (97.3%) as a negative marker. The combination of CEA and claudin-4 also showed relatively high diagnostic accuracy (94.6%) as a negative marker.

CONCLUSIONS

We recommend the combination of WT1 and calretinin as a positive maker, and the combination of CEA and claudin-4 as a negative marker, for differential diagnoses of SEM and PDSCC.

Malignant Peritoneum Mesothelioma with Hepatic Involvement: A Single Institution Experience in 5 Patients and Review of the Literature

Malignant peritoneal mesothelioma with invasion of the liver is an invariably fatal disease. We aimed to clarify the characteristics of malignant peritoneal mesothelioma cases with liver involvement. The clinical presentation, computed tomography images, and immunohistochemical and histopathological features of 5 patients with malignant peritoneal mesothelioma and liver involvement were evaluated. The diagnosis was established by imaging and immune profiles of the tumours. A review of 8 cases with primary or invading malignant mesothelioma in liver is presented. All 5 mesothelioma cases were asbestos-related. CT images of malignant peritoneal mesothelioma with the liver involvement typically showed that the lesion grew inside the liver along the capsule and was possibly accompanied by capsule breakthrough and extrahepatic infiltration. The tumours exhibited a common epithelioid appearance in all 5 patients and most cases revealed positive Cal, CK, and MC with negative CEA and HeP. Different from our findings, the review of literature revealed that most malignant mesothelioma of liver was due to primary intrahepatic malignant mesothelioma. Finally, we concluded that the diagnosis of malignant peritoneal mesothelioma cases with liver invasion is reliably achieved by the history of asbestos exposure, the characteristic CT imaging, and immune profiles of the tumours.

Value of calretinin immunostaining in diagnostic pathology: a review and update

Calretinin is a member of the EF-hand family of calcium-binding proteins. Because its expression is highly restricted to mesotheliomas, calretinin is, at present, the most commonly used positive mesothelioma marker that is most often recommended to be included in the various immunohistochemical panels used to assist in the differential diagnosis of these tumors. Calretinin expression has also been reported to be commonly expressed in a wide variety of other neoplasms, including sex cord-stromal tumors, adrenal cortical neoplasms, olfactory neuroblastomas, Schwann cell tumors, cardiac myxomas, and ameloblastomas. This article reviews the information that is currently available on calretinin expression in tumors and on its application as an immunohistochemical marker in diagnostic pathology.

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

Context

Immunohistochemistry has become an indispensable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome in the era of personalized medicine. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

Objective

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

Data Sources

Literature review, authors' research data, and personal practice experience.

Conclusions

This review article has shown that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. The discovery of new mutation-specific antibodies identifying a subset of specific gene-arranged lung tumors provides a promising alternative and cost-effective approach to molecular testing. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoiding potential diagnostic errors.

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

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

The carcinogenic effect of various multi-walled carbon nanotubes (MWCNTs) after intraperitoneal injection in rats

BACKGROUND

Biological effects of tailor-made multi-walled carbon nanotubes (MWCNTs) without functionalization were investigated in vivo in a two-year carcinogenicity study. In the past, intraperitoneal carcinogenicity studies in rats using biopersistent granular dusts had always been negative, whereas a number of such studies with different asbestos fibers had shown tumor induction. The aim of this study was to identify possible carcinogenic effects of MWCNTs. We compared induced tumors with asbestos-induced mesotheliomas and evaluated their relevance for humans by immunohistochemical methods.

METHODS

A total of 500 male Wistar rats (50 per group) were treated once by intraperitoneal injection with 10⁹ or 5 × 10⁹ WHO carbon nanotubes of one of four different MWCNTs suspended in artificial lung medium, which was also used as negative control. Amosite asbestos (10⁸ WHO fibers) served as positive control. Morbid rats were sacrificed and necropsy comprising all organs was performed. Histopathological classification of tumors and, additionally, immunohistochemistry were conducted for podoplanin, pan-cytokeratin, and vimentin to compare induced tumors with malignant mesotheliomas occurring in humans.

RESULTS

Treatments induced tumors in all dose groups, but incidences and times to tumor differed between groups. Most tumors were histologically and immunohistochemically classified as malignant mesotheliomas, revealing a predominantly superficial spread on the serosal surface of the abdominal cavity. Furthermore, most tumors showed invasion of peritoneal organs, especially the diaphragm. All tested MWCNT types caused mesotheliomas. We observed highest frequencies and earliest appearances after treatment with the rather straight MWCNT types A and B. In the MWCNT C groups, first appearances of morbid mesothelioma-bearing rats were only slightly later. Later during the two-year study, we found mesotheliomas also in rats treated with MWCNT D - the most curved type of nanotubes. Malignant mesotheliomas induced by intraperitoneal injection of different MWCNTs and of asbestos were histopathologically and immunohistochemically similar, also compared with mesotheliomas in man, suggesting similar pathogenesis.

CONCLUSION

We showed a carcinogenic effect for all tested MWCNTs. Besides aspect ratio, curvature seems to be an important parameter influencing the carcinogenicity of MWCNTs.

Establishing a panel of chemo-resistant mesothelioma models for investigating chemo-resistance and identifying new treatments for mesothelioma

Mesothelioma is inherently chemo-resistant with only 50% of patients responding to the standard of care treatments, and consequently it has a very grim prognosis. The aim of this study was to establish a panel of chemo-resistant mesothelioma models with clinically relevant levels of resistance as tools for investigating chemo-resistance and identifying new treatments for mesothelioma. Chemo-resistant cell lines were established in vitro and characterized in vivo using syngeneic Fischer rats. Tumors derived from all chemo-resistant cell lines were immunohistochemically classified as mesothelioma. Homozygous deletion of p16^INK4A/p14^ARF and increased expression of several ATP-binding cassette transporters were demonstrated, consistent with findings in human mesothelioma. Further, the acquisition of chemo-resistance in vitro resulted in changes to tumor morphology and overall survival. In conclusion, these models display many features corresponding with the human disease, and provide the first series of matched parental and chemo-resistant models for in vitro and in vivo mesothelioma studies.

Diagnostic value of claudin-4 marker in pleural and peritoneal effusion cytology: Does it differentiate between metastatic adenocarcinoma and reactive mesothelial cells?

BACKGROUND

Several markers have been used to make a distinction between metastatic adenocarcinoma and reactive mesothelial cells in the body cavity effusions. This study aimed to evaluate the diagnostic value of claudin-4 marker in making such a distinction.

MATERIALS AND METHODS

In this cross-sectional study, a total of 92 pleural/peritoneol effusions have been studied, including 47 cases of definite metastatic carcinoma and 45 cases of reactive mesothelium, and definitely negative for malignancy. Specimens were collected from patients; cell block samples were derived and used for immunohistochemical staining. The antibody used for immunohistochemical labeling was monoclonal anti-claudin-4. In the evaluation, membrane-bound reactivity was considered as significant and positive cases were defined when at least more than 10% of tumor cells were distinctly labeled.

RESULTS

Claudin-4 protein was positive in 40 specimens of metastatic carcinoma, while none of the cases of reactive mesothelium stained with the marker. This was not detected in the mesothelial cells, though. Positive staining for claudin-4 was significantly more frequent in metastatic carcinoma than in the reactive mesothelium (P > 0.0001). The sensitivity and specificity of claudin-4 to distinguish reactive mesothelium from metastatic carcinoma were 85% (95% confidence interval [CI], 71.1-93.8%) and 100% (95% CI, 91.1-100%), respectively. Furthermore, negative likelihood ratio was 0.15 (95% CI, 0.08-0.29).

CONCLUSION

The results of this study demonstrated that claudin-4 is less frequently expressed in reactive mesothelium. Thus, this claudin may be helpful in differentiating metastatic carcinoma from reactive mesothelial cells in pleural and peritoneal fluid cytology specimen.

[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.

Expression of mesothelioma-related markers in meningiomas: an immunohistochemical study

Background. Meningiomas are common intracranial tumors. Recently, histogenetic and phenotypic similarities between meningiomas and mesotheliomas have been proposed. We were interested in whether these similarities are reflected on the immunohistochemical level, which would add new potentially diagnostic markers for meningiomas. Methods. The expression of mesothelioma-related markers (D2-40, Calretinin, Keratin 5/6, WT1, and Methotheioma-Ab1) was investigated in 87 cases of meningiomas and compared to EMA expression. Results. 73.6% of meningioma cases were grade I, 20.7% were grade II, and 5.7% were grade III. 83.9% of meningioma cases were classical and 16.1% had special nonmeningothelial features. D2-40 was expressed in 37.9% of cases and was significantly restricted to classical meningiomas. Calretinin and WT1 were negative while Keratin 5/6 and Mesothelioma-Ab1 were weakly expressed in classical variants (5.7% and 3.4%, resp.). EMA was consistently expressed in all cases. Its expression was significantly higher than that of mesothelioma-related markers; this held true also when D2-40 expression was considered separately. Conclusions. Mesothelioma-related markers are not extensively expressed in meningiomas, a finding that argues against their proposed histogenetic and phenotypic similarities. Compared to EMA, the significantly lower expression of mesothelioma-related markers and their restricted expression to classical meningioma variants hamper their potential future use as diagnostic markers for meningioma.

A diagnosis of malignant pleural mesothelioma can be made by effusion cytology: results of a 20 year audit

AIMS

Cytological diagnosis of malignant pleural mesothelioma (MPM) is controversial, but has been used in our institution for over 30 years. To assess the role of effusion cytology in mesothelioma diagnosis we conducted an audit of pleural fluid cytology results over a 20 year period (1988-2007).

METHODS

Pleural samples were received from 6285 patients; data linkage with Western Australian Cancer and Mesothelioma Registries demonstrated that 815 of these patients had a diagnosis of MPM. Cytological examination of a pleural effusion specimen had been performed in 517 (63%) of these 815 patients.

RESULTS

Definitive cytological diagnosis of MPM was made in 377/517 cases, resulting in an 'absolute' sensitivity of 73%. An additional 66 patients were diagnosed as atypical/suspicious, resulting in a 'complete' sensitivity of 86%. If only biopsy/necropsy proven cases are considered, the absolute sensitivity is 68% and the complete sensitivity is 82%. There were no false positive diagnoses of malignancy; two patients with metastatic adenocarcinoma were initially diagnosed as MPM, prior to the availability of specific mesothelial markers, resulting in a positive predictive value of 99%.

CONCLUSIONS

Effusion cytology is an inexpensive, minimally invasive procedure which should be included in the diagnostic work-up of cases of suspected MPM.

Expression of Wilms' tumor gene (WT1) is associated with survival in malignant pleural mesothelioma

INTRODUCTION

Calretinin and Wilms' tumor gene (WT1) are mesothelial markers routinely used to confirm the diagnosis of malignant pleural mesothelioma (MPM). We investigated the prognostic value of calretinin and WT1 expression in predicting survival in a series of patients diagnosed with MPM in our institution.

MATERIALS AND METHODS

Fifty-two patients diagnosed of MPM were retrospectively reviewed. Calretinin and WT1 were stained for IHC analysis in formalin-fixed, paraffin-embedded sections and positivity was considered for tumors with >1 % of tumor cells stained. Survival data were calculated by the Kaplan-Meier method and Cox regression was used to evaluate the prognostic value of the variables.

RESULTS

Calretinin IHC expression was positive in 83.7 % of patients and WT1 in 78.1 %. A significant association of calretinin and WT1 expression with epithelial histology was detected (p = 0.030 and p = 0.010). We found a significant increase in OS in patients with epithelial subtype, PS1 and neutrophil-lymphocyte ratio (NLR) ≤5 (p < 0.05). In the IHC markers analysis, we found a significant increase in OS for patients with WT1 positive expression (16.4 vs. 2.3 m, p = 0.013), but not differences for calretinin expression (16.6 vs. 5.0 months, p = 0.37). In the multivariate analysis, epithelial histology and WT1 remained as significant prognostic factors for survival (p = 0.004 and p = 0.010, respectively).

CONCLUSION

In our series of 52 MPM patients, epithelial histology, PS, NLR and WT1 expression are significant prognostic factors for survival. We concluded that WT1, but not calretinin, is a useful prognostic factor in MPM. The role of WT1 assessment is worth of prospective validation in future studies on MPM.

Endosalpingiosis in peritoneal washings in women with benign gynecologic conditions: thirty-eight cases confirmed with paired box-8 immunohistochemical staining and correlation with surgical biopsy findings

BACKGROUND

To better define the cytomorphologic spectrum of endosalpingiosis in peritoneal washings (PWs) and thereby facilitate their distinction from well differentiated serous carcinoma, the authors examined PWs from women who underwent surgery and pathologic staging of lesions other than Mullerian malignancies and correlated the findings with surgical specimens.

METHODS

This was a retrospective review of medical records and PW specimens from 100 consecutive patients who had PWs coded as both "endosalpingiosis" and "negative for carcinoma" between 2002 and 2012. Thirty-eight of these patients had no gynecologic malignancies. Specimens had been prepared using cytocentrifugation and were stained using the Papanicolaou method. The cytologic findings evaluated were cell arrangement, number of cell groups per case, cellular atypia, and psammoma bodies. Smears also were assessed for paired box-8 (PAX8) immunostaining. The authors compared patients' staging biopsy findings with the findings from a review of the PWs.

RESULTS

PW specimens from 35 of 38 patients (92%) exhibited classic endosalpingiosis features: tubular or small branching papillary structures, some with psammoma bodies. Specimens from the 3 remaining patients displayed nonclassic features consistent with dislodged fallopian tube epithelium or endometriosis. From 2 to 20 clusters per slide and from 4 to 50 groups per case were identified. In a few cases, some cell clusters exhibited up to moderate cytologic atypia. Surgical findings included endometriosis, endosalpingiosis, both endometriosis and endosalpingiosis (12 patients; 31.6%), and a variety of unrelated pelvic lesions. All cases were PAX8-positive, confirming their Mullerian origin.

CONCLUSIONS

Endosalpingiosis in PWs can be diagnostically challenging. Awareness of intraoperative techniques and correlation with surgical biopsy findings are necessary to avoid a misdiagnosis of malignancy.

Localized mesothelioma tumour arising synchronously with a primary contralateral lung cancer

Mesothelioma is a malignant growth of mesothelial cells found in the serosal membrane of pleural, peritoneal and pericardial surfaces as a result of prolonged exposure to asbestos. Malignant pleural mesothelioma (MPM) typically presents itself in a diffuse pattern of growth over the pleura of the lung or in more rare cases as a localized focus (LMPM). We present the first reported case of a synchronous LMPM and non-small adenocarcinoma of the lung treated by sequential resections.

[Surgical aspects of malignant pleural mesothelioma: from the perspective of pathology]

The increased use of asbestos in Germany in the mid 1970s led occupational physicians, pulmonologists, thoracic surgeons and pathologists to the expectation of an increasing incidence and mortality in patients with pleural mesothelioma up to 2020. Prerequisite for curative surgery is a pathological anatomical tumor diagnosis on the basis of a biopsy and accurate tumor staging. In order to achieve reproducible results in the assessment of malignant pleural diseases, the pathological anatomical diagnosis of malignant pleural mesothelioma should be made according to the guidelines of the international mesothelioma interest group (IMIG). Currently used multimodal thoracic surgery therapeutic concepts present new challenges and problems to the pathological anatomical diagnosis and are discussed in this article.

Value of PAX8, PAX2, claudin-4, and h-caldesmon immunostaining in distinguishing peritoneal epithelioid mesotheliomas from serous carcinomas

Distinguishing between peritoneal epithelioid mesotheliomas and papillary serous carcinomas involving the peritoneum can be difficult on routine histological preparations, but this differential diagnosis can be facilitated by the use of immunohistochemistry. Recent investigations have indicated that PAX8, PAX2, claudin-4, and h-caldesmon are immunohistochemical markers that can assist in distinguishing between these two malignancies; however, much of the information published on the value of these markers is either insufficient or contradictory. The purpose of this study is to resolve some of the existing controversies and to fully determine the practical value of these markers for assisting in the differential diagnosis between peritoneal mesotheliomas and serous carcinomas. In order to do so, a total of 40 peritoneal epithelioid mesotheliomas and 45 serous carcinomas (15 primary, 30 metastatic to the peritoneum) were investigated. PAX8 and PAX2 nuclear positivity was demonstrated in 42 (93%) and 25 (56%) of the serous carcinomas, respectively, whereas none of the mesotheliomas expressed either marker. Forty-four (98%) of the serous carcinomas exhibited claudin-4 reactivity along the cell membrane, whereas none of the mesotheliomas were positive for this marker. All of the serous carcinomas and mesotheliomas were negative for h-caldesmon. Based on these results, it is concluded that PAX8 and claudin-4 have a higher sensitivity and specificity for assisting in discriminating between peritoneal epithelioid mesotheliomas and serous carcinomas when compared with all of the other positive carcinoma markers that are, at present, recommended to be included in the immunohistochemical panels used in this differential diagnosis. Even though it is highly specific, PAX2 has little practical value in the diagnosis of peritoneal epithelioid mesotheliomas as its sensitivity is low. The h-caldesmon is not useful.

Primary pleural squamous cell carcinoma misdiagnosed as localized mesothelioma: a case report and review of the literature

Primary pleural squamous cell carcinoma is very rare, and there is a lack of experience in the diagnosis and treatment of this condition. An asymptomatic 75-year-old man was referred to us after a right pleural nodule was found on computed tomography during a routine health examination. He underwent surgery for his pleural tumor twice over the following 2 years. Histopathological examination eventually led to a diagnosis of primary pleural squamous cell carcinoma.

Value of thyroid transcription factor-1 immunostaining in tumor diagnosis: a review and update

Thyroid transcription factor-1 (TTF-1) is a tissue-specific transcription factor that plays a critical role in the normal development of embryonic epithelial cells of the thyroid and lung. Because TTF-1 expression is highly restricted to epithelial tumors arising in these organs, it is, at present, one of the immunohistochemical markers most commonly used to assist in the differential diagnosis of carcinomas of the lung and thyroid. Recent studies, however, have reported that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought as it can be found to be expressed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Even though this unexpected TTF-1 positivity has been reported more frequently with the recently available SPT24 anti-TTF-1 monoclonal antibody, it has also been shown to occur with the commonly used 8G7G3/1 clone, albeit in a lower percentage of cases. Despite these findings, TTF-1 remains a very useful immunohistochemical marker in diagnostic pathology.

Adenocarcinoma cells in effusion cytology as a diagnostic pitfall with potential impact on clinical management: a case report with brief review of immunomarkers

Distinguishing metastatic carcinoma cells from reactive mesothelial cells in effusion samples is often challenging based on morphology alone. Metastatic carcinoma cells in fluid samples may mimic reactive mesothelial cells due to overlapping cytological features. We report a case of a pleural effusion in a 51-year-old female patient with a medical history significant for bilateral ovarian tumors and peritoneal implants diagnosed as serous tumor of borderline malignant potential. The effusion was composed almost entirely of adenocarcinoma cells that morphologically mimicked reactive mesothelial cells. The diagnosis of metastatic adenocarcinoma was made after a wide immunostaining panel of antibodies. Recognizing metastatic adenocarcinoma cells in effusion samples can be challenging and an accurate diagnosis may have significant impact on clinical management as demonstrated by this case.

Deciduoid mesothelioma: report of 21 cases with review of the literature

Deciduoid mesothelioma is a rare variant of epithelioid mesothelioma that was initially considered to occur exclusively in the peritoneum of young women who had no history of asbestos exposure and to be characterized by an aggressive clinical course, but it was later demonstrated that this tumor could also occur in the pleura of older men and women who had been exposed to asbestos. Some subsequent studies have also indicated that the clinical course is no different from that of conventional epithelioid mesothelioma. Herein are reported 21 cases of deciduoid mesothelioma that were investigated using a large panel of immunohistochemical markers, 9 of which were also studied by electron microscopy. Fifteen of the patients were male and 6 were female (mean age, 60 years). Seventeen of the cases originated in the pleura and four in the peritoneum. Histologically, all of the cases were composed of large, polygonal or ovoid cells with well-defined cell borders, dense eosinophilic cytoplasm, and single or multiple nuclei. In some cases, the cells exhibited a wide variation in their size and shape, frequent loss of cell cohesion, marked nuclear atypia, and high mitotic activity (>5 per 10 HPF); whereas, in others, the cells were more cohesive, less pleomorphic, and the mitotic activity low. As the survival of patients in the first group of cases was shorter (mean, 7 months), when compared with that of the latter (mean, 23 months), it is concluded that the differences in prognosis reported in deciduoid mesothelioma are due to the existence of a high-grade subgroup that presents highly aggressive clinical behavior. Therefore, when a high-grade deciduoid mesothelioma is present, it should be reported as it can significantly affect prognosis and treatment. The use of immunohistochemistry and electron microscopy in assisting in the differential diagnosis of deciduoid mesothelioma is also discussed.

Immunoreactivity for calretinin and keratins in desmoid fibromatosis and other myofibroblastic tumors: a diagnostic pitfall

Calretinin is an intracellular calcium-binding EF-hand protein of the calmodulin superfamily. It plays a role in diverse cellular functions, including message targeting and intracellular calcium signaling. It is expressed in the mesothelium, mast cells, some neural cells, and fat cells, among others. Because of its relative specificity for mesothelial neoplasms, calretinin is widely used as one of the primary immunohistochemical markers for malignant mesothelioma and in differentiating it from adenocarcinoma. On the basis of our sporadic observation on calretinin immunoreactivity in desmoid fibromatosis, we systematically evaluated calretinin, keratin cocktail (AE1/AE3), and WT1 immunoreactivity in 268 fibroblastic/myofibroblastic neoplasms. Calretinin was observed in 75% (44/58) of desmoid fibromatosis, 50% (21/42) of proliferative fasciitis, 23% (8/35) of nodular fasciitis, 33% (13/40) of benign fibrous histiocytoma, 35% (22/62) of malignant fibrous histiocytoma, and 13% (4/31) of solitary fibrous tumors but not in normal connective tissue fibroblasts at various sites. Keratin AE1/AE3 immunoreactivity was also commonly (6/13) present in the large ganglion-like cells of proliferative fasciitis and sometimes in nodular fasciitis (3/35), solitary fibrous tumor (3/27), and malignant fibrous histiocytoma (9/62). Nuclear immunoreactivity for WT1 or keratin 5 positivity was not detected in myofibroblastic tumors. On the basis of these observations, it can be concluded that calretinin and focal keratin immunoreactivity is fairly common in benign and malignant fibroblastic and myofibroblastic lesions. Calretinin-positive and keratin-positive spindle cells in desmoid and nodular fasciitis or calretinin-positive ganglion-like cells in proliferative fasciitis should not be confused with elements of epithelioid or sarcomatoid mesothelioma. These diagnostic pitfalls can be avoided with careful observation of morphology, quantitative differences in keratin expression, and use of additional immunohistochemical markers such keratin 5 and WT1 to verify true epithelial and mesothelial differentiation typical of mesothelioma.

Application of immunohistochemistry in the diagnosis of epithelioid mesothelioma: a review and update

A large number of immunohistochemical markers that can assist in the differential diagnosis of epithelioid mesotheliomas are currently available. Because these markers are expressed differently in the various types of carcinomas that can metastasize to the serosal membranes and can potentially be confused with epithelioid mesothelioma, their selection for inclusion in a diagnostic panel largely depends on the differential diagnosis, as well as on which ones work the best in a given laboratory. Traditionally, the panels used in the differential diagnosis of epithelioid mesothelioma have consisted of a combination of positive mesothelioma markers and broad-spectrum carcinoma markers. At present, a wide variety of organ-associated carcinoma markers such as thyroid transcription factor-1 and napsin A for the lung, PAX 8 and PAX 2 for the kidney, and Müllerian-derived tumors; gross cystic disease fluid protein-15 and mammaglobin for the breast; and CDX2 for intestinal differentiation are available, which can assist in establishing the site of origin of an adenocarcinoma when included in a diagnostic panel. This article provides updated information on the composition of the panels of markers recommended in the various differential diagnoses.

Melan A (A103) is not a marker of mesothelioma

Although a large number of immunohistochemical markers have been proven to be valuable in the differential diagnosis between epithelioid mesotheliomas and metastatic carcinomas involving the serosal membrane, no single antibody has been found that is absolutely sensitive and/or specific in making this distinction. A recent study reported melan A positivity in all 12 of the epithelioid mesotheliomas stained with a melan A antibody (clone A103). To fully determine the practical value of this antibody for assisting in the differential diagnosis of mesotheliomas, we investigated the expression of melan A (A103) in 40 mesotheliomas (27 epithelioid, 6 sarcomatoid, and 7 biphasic), 10 lung adenocarcinomas, and 10 serous carcinomas of the ovary. None of the mesotheliomas, lung adenocarcinomas, or serous carcinomas of the ovary were melan A (A103) positive. Similar staining results were observed in the 20 mesotheliomas immunostained in another institution using the same antibody clone from a different commercial source. On the basis of these results, it is concluded that in contrast to the initial report, melan A (A103) is not expressed in mesotheliomas and therefore, immunostaining with this antibody has no utility in the diagnosis of mesothelioma. The possible cause of the discrepancies between the results obtained in the present investigation and those of the initial study is discussed.

Value of PAX 8 immunostaining in tumor diagnosis: a review and update

PAX 8 is a transcription factor involved in the regulation of organogenesis of the thyroid gland, kidney, and Müllerian system. Recent studies have shown that, among tumors, PAX 8 is commonly expressed in epithelial tumors of the thyroid and parathyroid glands, kidney, thymus, and female genital tract. Although PAX 8 expression has also been reported in certain neuroendocrine tumors, including well-differentiated pancreatic neuroendocrine tumors, and duodenal and rectal carcinoids, as well as in B-cell lymphomas, it has recently been shown that the PAX 8 positivity reported in these tumors was due to a cross-reactivity of the antibody used with the N-terminal region of PAX 6 and PAX 5, respectively. Owing to its restricted expression, PAX 8 has proved to be a useful immunohistochemical marker with a wide range of diagnostic applications in surgical pathology, some of which are briefly reviewed.

Familial mesothelioma in first degree relatives

Occupational asbestos exposure is believed to be the primary etiologic link to mesothelioma. However, in the evaluation of familial mesothelioma, it is important to consider the possibility of household exposure to asbestos. In this study, we report a family in which the father with prolonged occupational asbestos exposure developed malignant pleural mesothelioma and his daughter 14 years later mesothelioma in situ with focally early invasion. Several reports of familial aggregations of mesothelioma strongly support that genetic factors in collaboration with environmental exposure may contribute etiologically to an as yet unknown fraction of occurrence of this disease.

Mesotheliomas with crystalloid structures: report of nine cases, including one with oncocytic features

Although the presence of crystalloids has historically been of largely academic interest or simply an intriguing curiosity, these structures have occasionally been useful in the differential diagnosis of some tumors. Crystalloids have only rarely been reported in mesotheliomas, and their presence in these tumors has not been sufficiently investigated, nor has their potential value as an ultrastructural marker for mesothelioma been established. The finding of a case of mesothelioma in which the vast majority of the neoplastic cells contained intracytoplasmic crystalloids prompted a search for these structures in 69 consecutive cases of mesothelioma (59 epithelioid, 7 sarcomatoid, 3 mixed-epithelioid sarcomatoid). Crystalloids were found in 9 (15%) of the 59 epithelioid mesotheliomas, indicating that these structures are not as rare as had been thought. That these inclusions were demonstrated in tumors exhibiting diverse histological patterns and were not confined to a single subtype of epithelioid mesothelioma indicates that, because of their unique morphology, when present, they can assist in the diagnosis of these tumors. In addition, oncocytic features were also seen in one of the cases with crystalloid inclusions. Pathologists should be aware of the fact that, even though uncommon, mesotheliomas can present oncocytic morphology and, therefore, these tumors should be included in the differential diagnosis of those neoplasms that display similar morphological features, and which can metastasize to the serosal membranes. To my knowledge, an oncocytic mesothelioma has not previously been reported.

Napsin A expression in lung and kidney neoplasia: a review and update

Napsin A is an aspartic protease present in the epithelial cells of the lung and kidney. Recent studies have shown that, in lung tumors, napsin A expression is restricted to lung adenocarcinomas, whereas among renal tumors, it is frequently expressed in renal cell carcinomas, especially the papillary and clear cell subtypes. Owing to its restricted expression, napsin A is a useful marker that can assist in the diagnosis of both lung adenocarcinomas and renal cell carcinomas.

Comparison of immunocytochemical sensitivity between formalin-fixed and alcohol-fixed specimens reveals the diagnostic value of alcohol-fixed cytocentrifuged preparations in malignant effusion cytology

The most commonly used fixative in effusion cytology is formalin. In the present study, the immunocytochemical properties of formalin-fixed and alcohol-fixed specimens were compared to evaluate the usefulness of alcohol-fixed cytocentrifuged preparations for routine cytologic diagnosis. A total of 269 effusion samples and 17 primary antibodies were used. The sensitivity of immunocytochemical studies in alcohol-fixed specimens was similar and correlated to that of formalin-fixed specimens, suggesting that alcohol-fixed cytocentrifuged preparations are useful in effusion cytology. Pretreatment with or without heat-induced antigen retrieval revealed that antigen retrieval was unnecessary for immunocytochemical studies with most primary antibodies in alcohol-fixed cytocentrifuged preparations. The present study describes the use of immunocytochemical studies with alcohol-fixed cytocentrifuged preparations for diagnosis in routine effusion cytology.