Immunohistochemical detection of GLUT-1 can discriminate between reactive mesothelium and malignant mesothelioma

Diagnostic performance of immunohistochemistry markers for malignant pleural mesothelioma diagnosis and subtypes. A systematic review and meta-analysis

BACKGROUND

Malignant pleural mesothelioma (MPM) poses diagnostic challenges due to its resemblance to benign pleural pathologies and different histological subtypes. Several immunohistochemistry markers have been employed to aid in accurate diagnosis.

METHODS

The present systematic review and meta-analysis aimed to assess the diagnostic performance of various immunohistochemistry markers in malignant pleural mesothelioma diagnosis and its histological subtypes. Following the PRISMA guidelines, we systematically searched the literature for articles on using different immunohistochemical markers in MPM and its histological subtypes. EMBASE, LILACS, MEDLINE, and Virtual Health Library were searched for studies published up to August 2023. We used the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) criteria to assess the quality of the included articles. Meta-analyses were performed to determine prevalence using a random-effects model.

RESULTS

103 studies met the inclusion criteria, comprising a diverse range of immunohistochemistry markers. EMA and desmin-loss exhibited high sensitivity (96% and 92%, respectively) in distinguishing malignant pleural mesothelioma from benign pleural pathologies. Specificity was notably high for both BAP1-loss and survivin expression at 100%. Subtype-specific analyses demonstrated that EMA and HEG1 were sensitive markers for epithelioid mesothelioma, while GLUT1 showed high sensitivity for sarcomatoid mesothelioma. In cases comparing epithelioid mesothelioma and lung adenocarcinoma, CAM5.2 and calretinin displayed high sensitivity, while WT1 and BAP1-loss demonstrated exceptional specificity for malignant epithelioid mesothelioma. In the case of sarcomatoid mesothelioma and sarcomatoid lung carcinoma, GATA3 exhibited the most heightened sensitivity, while GATA3 and D2-40 displayed the best specificity for sarcomatoid malignant mesothelioma diagnosis.

CONCLUSION

Immunohistochemistry markers are essential in accurately diagnosing malignant pleural mesothelioma and its histological subtypes. This systematic review and meta-analysis provide a comprehensive insight into the diagnostic performance of these markers, facilitating their potential clinical utility in the discrimination of malignant pleural mesothelioma from other pleural pathologies and the differentiation of malignant pleural mesothelioma subtypes.

Benign Mesothelial Proliferations of the Tunica Vaginalis Testis

The correct diagnosis of mesothelial proliferations is a classic problem for pathologists, and one which has important clinical implications. A significant number of such cases appear associated with recurrent hydrocele, as an irritative/reactive response to this condition. The morphological spectrum of mesothelial lesions in this topography is broad, and a set of benign conditions may appear, sometimes with florid gross features and cytologic pseudo-atypia. Here, we present two different examples in which malignancy was initially considered in the differential diagnosis.

Nivolumab-induced peritonitis with peritoneal mesothelial hyperplasia mimicking metastatic mesothelioma

A 57-year-old man developed a mesothelial proliferation in the peritoneum, several months after he was diagnosed with biopsy-proven epithelioid mesothelioma of the pleura and having undergone several treatments with checkpoint inhibitor immunotherapy. The differential diagnosis was metastatic mesothelioma from the lung primary, versus a reactive process. A diagnosis of atypical mesothelial proliferation was made. Follow-up CT showed no evidence of abdominal disease 5 months later. The complication of serositis following checkpoint inhibitor therapy is reviewed, as well as the differential diagnosis between reactive mesothelial hyperplasia and epithelioid mesothelioma.

Osteopontin, GLUT1 and Ki-67 expression in malignant peritoneal mesothelioma: prognostic implications

Background

Malignant peritoneal mesothelioma is the most common primary peritoneal neoplasm. The only universally recognised pathological prognostic factor is histopathological subtype. Prognostic markers based on patient features and clinical stages have been disappointing.

Aims

To assess the prognostic role of several clinicopathological features in a retrospective cohort of 60 patients diagnosed with peritoneal mesothelioma.

Methods

Sixty patients were centrally collected and were immunohistochemically analysed for the expression of osteopontin (OPN), GLUT1 and Ki‐67. Labelling was assessed by two pathologists. Complete clinical information and follow‐up were obtained from patients' records.

Results

OPN expression was identified in 52 (86.6%) of 60 specimens, and GLUT1 in 39 (65%) of 60 specimens. Univariate Cox regression analysis showed that a lower peritoneal carcinomatosis index (PCI), tumour‐directed treatment (chemotherapy or surgery alone or in any combination), lower Ki‐67, GLUT1 and lower OPN expression had a statistically significant positive effect on overall survival (OS). PCI (hazard ratio (HR) = 1.032 (95% confidence interval (CI): 1.000–1.067); P = 0.054) and tumour‐directed treatment (HR = 0.211 (95% CI: 0.104–0.430); P < 0.001), Ki‐67 (HR = 22.326 (95% CI: 3.523–141.498); P = 0.003) and OPN (HR = 7.268 (95% CI: 1.771–29.811); P = 0.009) retained independent prognostic significance in the multivariate analysis, all with a positive effect on OS with the exception of GLUT1.

Conclusions

OPN, Ki‐67, treatment and PCI were independent indicators for OS, and a higher level of OPN expression correlated significantly with poorer OS.

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.

HEG1, BAP1, and MTAP are useful in cytologic diagnosis of malignant mesothelioma with effusion

BACKGROUND

The specificity and sensitivity of HEG1 for malignant mesothelioma (MM) is high. The use of BAP1/MTAP immunohistochemistry (IHC) is recommended to separate benign and malignant mesothelial proliferations. We determined how ancillary techniques can be used for the cytological diagnosis of MM with effusion.

METHODS

Cell blocks from effusions from cases with MM, reactive mesothelial cells (RMCs), and carcinomas were analyzed by IHC with HEG1, BAP1, and MTAP and with homozygous deletion (HD) of CDKN2A by fluorescence in situ hybridization. Staining scores were calculated for IHC by adding the number of categories for the staining intensity and the staining extension.

RESULTS

HEG1 was positive in all (41/41) MMs, but negative in carcinomas, except for ovarian carcinomas. Overall 76.9% (20/26) of RMCs and 28.6% (6/21) of ovarian carcinomas expressed HEG1. BAP1 loss was found in 71.1% of MMs, but none was found in RMCs. MTAP loss was found in 76.2% of MMs, but none was found in RMCs. 73.9% of MMs harbored HD of CDKN2A. There was concordance between loss of MTAP and HD of CDKN2A in 95% of MMs.

CONCLUSION

HEG1 is a good marker for mesothelial differentiation in effusion cytology. HD of CDKN2A is frequently observed in cell blocks from effusions of MMs, and MTAP IHC may act as a surrogate for HD of CDKN2A. Cell block analysis is recommended for effusions of unknown origins with the following methods: IHC with HEG1 and claudin 4 to validate the mesothelial origin, followed by BAP1 and MTAP IHC to confirm malignancy.

Diagnostic value of GLUT-1 in distinguishing malignant mesothelioma from reactive mesothelial cells: a meta-analysis

Background: Previous studies have demonstrated the diagnostic value of glucose transporter 1 (GLUT-1) to distinguish malignant mesothelioma (MM) from reactive mesothelial cells (RMC), but the results are inconsistent. The purpose of this meta-analysis is to investigate the diagnostic accuracy of GLUT-1 in distinguishing MM from RMC.Methods: A systematical search was conducted until May 2019 in PubMed, Medline, Embase and the Cochrane Library. The revised tool for the quality assessment of diagnostic accuracy studies (QUADAS-2) was used to assess the quality of the eligible studies. The Stata15 and Review Manager5.3 software programmes were used to perform the meta-analysis.Results: A total of 24 studies, including 969 MM patients and 1080 RMC individuals were explored in the meta-analysis. The summary assessments revealed that the pooled sensitivity was 0.73 (95% CI, 0.62-0.81) and the pooled specificity was 0.95 (95% CI, 0.91-0.98). The area under the summary ROC curve (AUC) was 0.93 (95% CI: 0.91-0.95).Conclusions: GLUT-1 is highly accurate to distinguish MM from RMC.

Can novel adipokines, asprosin and meteorin-like, be biomarkers for malignant mesothelioma?

Malignant mesothelioma (MM) is a rare tumor of serous surfaces that has a poor prognosis. Cancer is a multistage process by which cells undergo metabolic and behavioral changes that cause excessive and untimely proliferation. Asprosin (ASP) and meteorin-like (METRNL) are two peptides associated with glucose and energy metabolism. We used immunohistochemistry to investigate whether these peptides could be biomarkers for diagnosis and treatment of MM. We reviewed 30 cases of MM and 30 cases of reactive mesothelial hyperplasia (RMH); we used the cases with RMH as control group. The specimens were examined using immunohistochemical staining for ASP and METRNL. ASP and METRNL immunoreactivity was more prominent in the MM specimens than the RMH specimens. Therefore, ASP and METRNL potentially could be used as markers for differentiating MM from benign diseases.

Highly expressed EZH2 in combination with BAP1 and MTAP loss, as detected by immunohistochemistry, is useful for differentiating malignant pleural mesothelioma from reactive mesothelial hyperplasia

OBJECTIVE

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm with poor prognosis. Loss of BRCA-associated protein 1 (BAP1) protein expression as detected by immunohistochemistry (IHC) and homozygous deletion (HD) of the 9p21 locus as detected by fluorescence in situ hybridization (FISH) permits differentiation of MPM from reactive mesothelial hyperplasia (RMH). We have previously reported that detecting the loss of methylthioadenosine phosphorylase (MTAP) using IHC is a surrogate assay for 9p21 FISH. Furthermore, enhancer of zeste homolog 2 (EZH2), which encodes a component of polycomb repressor complex 2 (PRC-2), has been overexpressed in various tumors as well as MPM. In the current study, we investigated whether EZH2 IHC assay, alone or in combination with BAP1 and MTAP IHC, is useful for distinguishing MPM from RMH.

MATERIALS AND METHODS

We examined IHC expression of EZH2, BAP1, and MTAP, and 9p21 FISH in MPM (n = 38) and RMH (n = 29) and analyzed the sensitivity and specificity of each detection assay for distinguishing MPM from RMH.

RESULTS AND CONCLUSION

EZH2, BAP1, and MTAP IHC, and 9p21 FISH were characterized by a 100% specificity each and 44.7%, 52.6%, 47.4%, and 65.8% sensitivities, respectively. A combination of EZH2 and BAP1 IHC, and 9p21 FISH showed the greatest sensitivity (89.5%). Using IHC alone (EZH2, BAP1, and MTAP IHC) also yielded a good sensitivity of 86.9%; this level is high enough for routine diagnostics. There were no statistically significant associations between expression of EZH2 and that of other markers (BAP1 and MTAP IHC) or 9p21 HD. However, a high expression level of EZH2 was significantly associated with short survival (P = 0.025). In conclusion, adding a high expression level of EZH2 to a combination of BAP1 and MTAP loss, all detected by IHC, demonstrated useful for discriminating MPM from RMH.

Loss of BAP1 Expression in Atypical Mesothelial Proliferations Helps to Predict Malignant Mesothelioma

Distinguishing reactive mesothelial proliferation from malignant mesothelioma (MM) can be difficult, particularly on small biopsies. In this scenario, a diagnosis of atypical mesothelial proliferation might be rendered. However, the distinction between a reactive process and MM is important for prognosis and treatment. Recently, loss of BRCA1-associated protein 1 (BAP1) expression and/or homozygous deletion of CDKN2A were identified in some MM, but not in reactive mesothelial proliferations. We studied 34 cases of atypical mesothelial proliferation from our institutional files (1993 to 2016) for BAP1 expression, deletion of CDKN2A, and clinical outcome. Fifteen of 34 patients (44%) were subsequently diagnosed with MM. BAP1 expression was lost in 6 of these 15 (40%) patients. Ten of 15 (67%) patients died of disease within a median time of 18.2 months. BAP1 expression was also lost in 1 case of probable MM. In this case atypical mesothelial proliferation was identified in the pleura during a lobectomy procedure for lung adenocarcinoma. Follow-up of 57.0 months was remarkable for visceral and parietal pleural thickening with continued unilateral effusion identified on imaging studies but no subsequent definitive diagnosis of MM. CDKN2A studies by fluorescence in situ hybridization (performed in 31 cases) found no homozygous deletion of that gene in any case. In conclusion, loss of BAP1 expression in atypical mesothelial proliferation helps to predict MM and is a useful adjunct test in these cases. Homozygous deletion of CDKN2A in mesothelial cell proliferations did not prove to be useful to predict MM in cases of atypical mesothelial proliferation.

Well-differentiated papillary mesothelioma: A 17-year single institution experience with a series of 75 cases

We present our experience with 75 cases of well-differentiated papillary mesothelioma (WDPM) that were diagnosed at our institution between 2000 and 2017. The patients included 58 females and 17 males with age ranging from 18 to 69 years (mean, 42 years). Clinically, the vast majority of WDPMs were incidental findings during laparotomy or laparoscopic surgery for a variety of benign or malignant disease. The lesion manifested as either a small solitary nodule or multiple miliary nodules on the peritoneum or serosal surfaces of internal organs. Histologically, 67 cases were consistent with a classical WDPM, of which 6 cases contained microinvasive foci and 1 case had malignant transformation. Eight cases were hybrid tumors with variable combined component of adenomatoid tumor (n = 4), multicystic mesothelioma (n = 2), and both (n = 2). By immunohistochemistry, besides calretinin, D2-40, CK5/6 and WT1, 94% (29/31) of cases also showed immunostaining for PAX8. In comparison, PAX8 staining was only present in 12% (6/50) of epithelioid malignant mesothelioma selected as control cases. Follow-up information available in 46 cases revealed no signs of tumor progression or local recurrence except for the case that showed transformation to a fully malignant mesothelioma after a period of 15 years. Our comprehensive study further expanded the clinical and histopathological spectrum of WDPM. Compared with epithelioid malignant mesothelioma, PAX8 staining is highly sensitive and specific for WDPM (P < 0.001).

Benign multicystic mesothelioma and peritoneal inclusion cysts: are they the same clinical and histopathological entities? A systematic review to find an evidence-based management

PURPOSE

Peritoneal mesothelial cysts (PMC) are a clinical dilemma because of their true pathogenic nature. Many definitions have been associated with PMC, including "benign multicystic mesothelioma", "cystic mesothelioma", "multilocular peritoneal inclusion cysts", ''inflammatory cysts of the peritoneum" or "postoperative peritoneal cyst".

METHODS

We herein performed a systematic review of the literature focusing on clinical and histopathological aspects of PMC, diagnosis, and therapies. Moreover, we described our experience with a case of PMC in a young female.

RESULTS

Since there is often a history of prior surgery or inflammatory disease, most authors consider PMC of reactive origin. However, in some cases they occur without any documentable signs of disease or injury. A variety of clinical findings can complicate the preoperative assessment and a multitude of histological pictures may potentially lead to a misdiagnosis. The absence of a uniform treatment strategy and lack of long-term follow-up often hinder the accurate definition leading to unnecessary or unnecessarily aggressive therapy.

CONCLUSIONS

PMC are more common than had previously been thought. Most authors consider them non-neoplastic; thus the designation of "peritoneal inclusion cyst" is preferable. The term "mesothelioma" should be used only in cases of histological evidences of atypia. The high rates of recurrence suggest that the goal of treatment should not be necessarily complete eradication, but symptomatic relief through individualized treatment. This is a topic of particular importance, especially in young female where recurrence rates could be lower than those reported in adults and where an improperly aggressive treatment could have repercussions on fertility.

Molecular markers and new diagnostic methods to differentiate malignant from benign mesothelial pleural proliferations: a literature review

Malignant pleural mesothelioma (MPM) is an aggressive tumor associated with asbestos exposure. Histopathological analysis of pleural tissues is the gold standard for diagnosis; however, it can be difficult to differentiate malignant from benign pleural lesions. The purpose of this review is to describe the most important biomarkers and new diagnostic tools suggested for this differential diagnosis. There are many studies concerning the separation between MPM and benign pleural proliferations from both pleural tissues or effusions; most of them are based on the evaluation of one or few biomarkers by immunohistochemistry (IHC) or enzyme-linked immunosorbent assays (ELISAs), whereas others focused on the identification of MPM signatures given by microRNA (miRNA) or gene expression profiles as well as on the combination of molecular data and classification algorithms. None of the reported biomarkers showed adequate diagnostic accuracy, except for p16 [evaluated by fluorescent in situ hybridization (FISH)] and BAP1 (evaluated by IHC), both biomarkers are recommended by the International Mesothelioma Interest Group guidelines for histological and cytological diagnosis. BAP1 and p16 showed a specificity of 100% in discerning malignant from benign lesions because they are exclusively unexpressed or deleted in MPM. However, their sensitivity, even when used together, is not completely sufficient, and absence of their alterations cannot confirm the benign nature of the lesion. Recently, the availability of new techniques and increasing knowledge regarding MPM genetics led to the definition of some molecular panels, including genes or miRNAs specifically deregulated in MPM, that are extremely valuable for differential diagnosis. Moreover, the development of classification algorithms is facilitating the application of molecular data for clinical practice. Data regarding new diagnostic tools and MPM signatures are absolutely promising; however, before their application in clinical practice, a prospective validation is necessary, as these approaches could surely improve the differential diagnosis between malignant and benign pleural lesions.

Immunohistochemical Evaluation of Glucose Transporter Type 1 in Epithelial Dysplasia and Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and some of these have been documented in association or preceded by oral epithelial dysplasia (OED). Aggressive cancers with fast growth have demonstrated overexpression of some glucose transporters (GLUTs). Thus, the aim of this study was to analyze the immunohistochemical expression of the glucose transporter, GLUT-1, in OEDs and OSCCs, seeking to better elucidate the biological behavior of neoplasias. Fifteen cases were selected this research of both lesions. Five areas were analyzed from each case by counting the percentage of positive cells at 400x magnification. Immunoreactivity of GLUT-1 was observed in 100% of the samples ranging from 54.2% to 86.2% for the OSCC and 73.9% to 97.4% for the OED. Statistical test revealed that there was greater overexpression of GLUT-1 in OED than the OSCC (p=0.01). It is believed the high expression of GLUT-1 may reflect the involvement of GLUT-1 in early stages of oral carcinogenesis.

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

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

Increased Expression of the Glucose Transporter Type 1 Gene Is Associated With Worse Overall Survival in Resected Pancreatic Adenocarcinoma

OBJECTIVES

There is currently no reliable method to predict the risk of relapse after curative resection of early-stage pancreatic adenocarcinoma. Increased glucose metabolism observed on F-fluorodeoxyglucose positron emission tomography (PET) by malignant cells, the Warburg effect, is a well-known characteristic of the malignant phenotype. We investigated the role of glucose transporter type 1 (GLUT-1) gene expression, a glucose cell plasma membrane transporter, in early-stage pancreatic cancer.

METHODS

Associations between GLUT-1 gene expression with PET maximum standardized uptake values and histologic grade were investigated in early-stage pancreatic adenocarcinoma patients. Multivariate analysis was conducted to determine predictors of prognosis. Cox proportional hazard model was used for survival analysis.

RESULTS

Sixty-three patients had GLUT-1 gene analysis performed, and 50 patients had both GLUT-1 analysis and PET scan. Patients with high GLUT-1 gene expression had a decreased overall survival by univariate analysis using Cox proportional hazard model (hazard ratio, 2.82; P = 0.001) and remained significant on multivariate analysis (hazard ratio, 2.54; P = 0.03). There was no correlation of GLUT-1 gene expression with histologic grade or PET maximum standardized uptake values.

CONCLUSIONS

Increased GLUT-1 gene expression was associated with a decreased overall survival in pancreatic adenocarcinoma. This supports increased GLUT-1 gene expression as a potential prognostic marker in resected pancreatic adenocarcinoma.

The legacy of the F344 rat as a cancer bioassay model (a retrospective summary of three common F344 rat neoplasms)

The Fischer 344 (F344) rat was used by the National Toxicology Program (NTP) for over 5 decades for toxicity and carcinogenicity studies. However, in 2006, the NTP decided to switch to a different rat stock due largely to high background control incidences of Leydig cell tumors (LCTs) and mononuclear cell leukemia (MNCL), also known as large granular lymphocytic (LGL) leukemia. In the current review, we aim (1) to provide a summary of NTP bioassays with treatment-associated effects involving MNCL and LCTs in addition to male F344-specific tunica vaginalis mesothelioma (TVM); (2) to describe important pathobiological differences between these F344 rat tumor responses and similar target tissue-tumor response in humans; and (3) to present the NTP reasons for switching away from the F344 rat. We show that due to the highly variable background incidence of F344 MNCL, more reliance on historical control data than is usual for most tumor responses is warranted to evaluate potential effect of any chemical treatment in this rat strain. The high spontaneous incidence of LCTs in the testes of male F344 rats has made this tumor endpoint of little practical use in identifying potential testicular carcinogenic responses. TVM responses in F344 rats have a biological plausible relationship to LCTs unlike TVM in humans. Given their high spontaneous background incidence and species-specific biology, we contend that MNCL and LCT, along with TVM responses, in F344 rat carcinogenicity studies are inappropriate tumor types for human health risk assessment and lack relevance in predicting human carcinogenicity.

Use of Anti-Noxa Antibody for Differential Diagnosis between Epithelioid Mesothelioma and Reactive Mesothelial Hyperplasia

OBJECTIVES

The histological differential diagnosis between epithelioid mesothelioma (EM) and reactive mesothelial hyperplasia (RMH) is not always straightforward. The aim of the present study was to search for new immunohistochemical markers to distinguish EM from RMH.

METHODS

We evaluated and compared the expression of apoptosis-related genes in EM and RMH by real-time RT-PCR array analysis followed by clustering of significant gene expression. Immunohistochemical staining and statistical analysis of Noxa expression in 81 cases of EM and 55 cases of RMH were performed and compared with the utility of other previously reported antibodies such as Desmin, EMA, GLUT-1, IMP-3 and CD146.

RESULTS

Noxa mRNA expression levels were found to be increased in EM when compared to RMH by RT-PCR array analysis. In the immunohistochemical analysis, Noxa showed sensitivity of 69.0%, specificity of 93.6% and positive predictive value of 93.0% as a positive marker of EM in distinguishing it from RMH, and these values were almost similar to IMP-3.

CONCLUSION

Noxa is a marker with relatively high specificity, and can be used to distinguish EM from RMH. It would be a valuable addition to the current antibody panel used for the differential diagnosis of EM and RMH.

Deletion status of p16 in effusion smear preparation correlates with that of underlying malignant pleural mesothelioma tissue

Differentiating malignant pleural mesothelioma (MPM) cells morphologically from reactive mesothelial hyperplasia cells is problematic. Homozygous deletion (HD) of p16 (CDKN2A), detected by FISH, is a good marker of malignancy and is useful to differentiate between these cells. However, the correlation between the p16 status of effusion smears and that of the underlying MPM tissues has not been investigated. We used p16‐specific FISH to investigate 20 cases of MPM from which both effusion cytologic smears and histologic specimens were available. In five cases, histologic specimens included both an invasive component and surface mesothelial proliferation. In 14 cases (70%), MPM cells in both tissue sections and effusion smears were p16 HD‐positive. Conversely, MPM cells in the remaining six tumors (30%) were p16 HD‐negative in both tissue sections and effusion smears. For all five MPM cases with surface mesothelial proliferations and invasive components, the effusion smears, surface mesothelial proliferations, and invasive MPM components all displayed p16 deletion. Moreover, the extent to which p16 was deleted in smears highly correlated with the extent of p16 deletion in tissues. The p16 deletion percentages were also similar among smears, tissue surface proliferations, and invasive components. In cases with clinical and radiologic evidence of a diffuse pleural tumor, detection of p16 deletion in cytologic smear samples may permit MPM diagnosis without additional tissue examination. However, the absence of p16 deletion in cytologic smear samples does not preclude MPM.

Loss of expression of BAP1 is a useful adjunct, which strongly supports the diagnosis of mesothelioma in effusion cytology

Although most mesotheliomas present with pleural effusions, it is controversial whether mesothelioma can be diagnosed with confidence in effusion cytology. Therefore, an ancillary marker of malignant mesothelial cells applicable in effusions would be clinically valuable. BRCA-1-associated protein (BAP1) is a tumor suppressor gene, which shows biallelic inactivation in approximately half of all mesotheliomas. We investigated whether loss of BAP1 expression by immunohistochemistry can be used to support a diagnosis of mesothelioma in effusion cytology. Immunohistochemistry for BAP1 was performed on cell blocks and interpreted blinded. 43 of 75 (57%) effusions associated with confirmed mesothelioma showed negative staining with positive internal controls. Of 57 effusions considered to have atypical mesothelial cells in the absence of a definitive diagnosis of mesothelioma, 8 cases demonstrated negative staining for BAP1. On follow-up six of these patients received a definitive diagnosis of mesothelioma in the subsequent 14 months (two were lost to follow-up immediately, and mesothelioma could not be excluded). Only 5 of 100 consecutive benign effusions were interpreted as BAP1 negative. One of these patients died soon after and mesothelioma could not be excluded. On unblinded review the four other patients with apparently negative BAP1 staining but no malignancy lacked convincing positive staining in non-neoplastic cells suggesting that BAP1 immunohistochemistry may have initially been misinterpreted. 47 effusions with adenocarcinoma were BAP1 positive. We conclude that loss of BAP1 expression, while not definitive, can be used to support the diagnosis of mesothelioma in effusion cytology. We caution that interpretation of BAP1 immunohistochemistry on cell block may be difficult and that convincing positive staining in non-neoplastic cells is required before atypical cells are considered negative. We also note that BAP1 loss is not a sensitive test as it occurs in only half of all mesotheliomas and cannot be used to exclude the diagnosis.

BAP1 (BRCA1-associated protein 1) is a highly specific marker for differentiating mesothelioma from reactive mesothelial proliferations

The distinction between malignant mesothelioma and reactive mesothelial proliferation can be challenging both on histology and cytology. Recently, variants of the BRCA1-associated protein 1 (BAP1) gene resulting in nuclear protein loss were reported in hereditary and sporadic mesothelioma. Using immunohistochemistry, we evaluated the utility of BAP1 expression in the differential diagnosis between mesothelioma and other mesothelial proliferations on a large series of biopsies that included 212 mesotheliomas, 12 benign mesothelial tumors, and 42 reactive mesothelial proliferations. BAP1 stain was also performed in 70 cytological samples (45 mesotheliomas and 25 reactive mesothelial proliferations). BAP1 was expressed in all benign mesothelial tumors, whereas 139/212 (66%) mesotheliomas were BAP1 negative, especially in epithelioid/biphasic compared with sarcomatoid/desmoplastic subtypes (69% vs 15%). BAP1 loss was homogeneous in neoplastic cells except for two epithelioid mesotheliomas showing tumor heterogeneity. By fluorescence in situ hybridization, BAP1 protein loss was paralleled by homozygous deletion of the BAP1 locus in the vast majority of BAP1-negative tumors (31/41, 76%), whereas 9/10 BAP1-positive mesotheliomas were normal. In biopsies interpreted as reactive mesothelial proliferation BAP1 loss was 100% predictive of malignancy, as all 6 cases subsequently developed BAP1-negative mesothelioma, whereas only 3/36 (8%) BAP1-positive cases progressed to mesothelioma. On cytology/cell blocks, benign mesothelial cells were invariably positive for BAP1, whereas 64% of mesotheliomas showed loss of protein; all 6 cases showing BAP1 negativity were associated with histological diagnosis of BAP1-negative mesothelioma. BAP1 stain also showed utility in the differential of mesothelioma from most common pleural and peritoneal mimickers, such as lung and ovary carcinomas, with specificity and sensitivity of 99/70% and 100/70%, respectively. Our results show that BAP1 protein is frequently lost in mesothelioma, especially of epithelioid/biphasic subtype and is commonly associated with homozygous BAP1 deletion. BAP1 immunostain represents an excellent biomarker with an unprecedented specificity (100%) in the distinction between benign and malignant mesothelial proliferations. Finding BAP1 loss in mesothelial cells should prompt to immediately reevaluate the patient; moreover, it might be useful in mapping tumor extent and planning surgical resection.

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.

Practical utility of insulin-like growth factor II mRNA-binding protein 3, glucose transporter 1, and epithelial membrane antigen for distinguishing malignant mesotheliomas from benign mesothelial proliferations

The differentiation of malignant mesotheliomas and benign mesothelial proliferations is crucial in determining patient care and prognosis. But, this distinction can be extremely difficult, particularly in small biopsies. Recently, insulin-like growth factor II mRNA-binding protein 3 (IMP3) and glucose transporter 1 (GLUT-1) have been reported as specific and sensitive markers in the distinction of mesotheliomas from benign mesothelial proliferations. The purpose of this study is to evaluate the utility of IMP3, GLUT-1, and epithelial membrane antigen (EMA) immunohistochemistry for distinguishing mesotheliomas from benign mesothelial proliferations. Immunoexpression of IMP3, GLUT-1, and EMA was evaluated in 88 malignant mesotheliomas, 35 adenomatoid tumors, and 20 benign lung tissues with reactive mesothelial cells. The sensitivity for IMP3, GLUT-1, and EMA was 37%, 21%, and 41%, respectively. The specificity for IMP3, GLUT-1, and EMA was 100%. When IMP3, GLUT1, and EMA combined, the sensitivity was 66% for IMP3/EMA staining, 53% for GLUT-1/EMA staining, and 45% for IMP3/GLUT-1. Use of IMP3 and EMA together is more helpful to distinguish malignant mesotheliomas from benign mesothelial proliferations than the use of IMP3 or EMA alone.

Differential expression of extracellular matrix constituents and cell adhesion molecules between malignant pleural mesothelioma and mesothelial hyperplasia

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a highly aggressive neoplasm associated with asbestos exposure. Currently, the molecular mechanisms that induce MPM development are still unknown. The purpose of this study was to identify new molecular biomarkers for mesothelial carcinogenesis.

METHODS

We analyzed a panel of 84 genes involved in extracellular matrix remodeling and cell adhesion by polymerase chain reaction (PCR) array in 15 samples of epithelioid mesothelioma and 10 samples of reactive mesothelial hyperplasia (MH; 3 of 25 samples were inadequate for mRNA analysis). To validate the differentially expressed genes identified by PCR array, we analyzed 27 more samples by immunohistochemistry, in addition to the 25 samples already studied.

RESULTS

Twenty-five genes were differentially expressed in MPM and MH by PCR array. Of these we studied matrix metalloproteinase 7 (MMP7), MMP14, CD44, and integrin, alpha3 expression by immunohistochemistry in 26 epithelioid MPM and 26 MH samples from the entire series of 52 cases. We observed higher MMP14 and integrin, alpha3 expression in MPM samples compared with MH samples (p = 0.000002 and p = 0.000002, respectively). Conversely, CD44 expression was low in most (57.7%) mesothelioma samples but only in 11.5% of the MH samples (p = 0.0013). As regards MMP7, we did not observe differential expression between MH and MPM samples.

CONCLUSIONS

We have extensively studied genes involved in cell adhesion and extracellular matrix remodeling in MPM and MH samples, gaining new insight into the pathophysiology of mesothelioma. Moreover, our data suggest that these factors could be potential biomarkers for MPM.

The evaluation of immunohistochemical markers and thymic cortical microenvironmental cells in distinguishing thymic carcinoma from type b3 thymoma or lung squamous cell carcinoma

Thymic carcinoma (TC) is often very difficult to distinguish from type B3 thymoma and lung squamous cell carcinoma (L-SCC) involving the anterior mediastinum. The present study evaluated the usefulness of immunohistochemical markers including c-Kit, CD5, glucose transporter-1 (GLUT-1), claudin-1 (CLDN-1), thymoproteasome β5t, p53 and Ki-67 (MIB-1) and thymic cortical environmental marker cells, cortical thymocytes (c-Thy) and thymic cortical dendritic macrophages (TCDMs) in distinguishing thymic carcinoma (TC) from type B3 thymoma or lung squamous cell carcinoma (L-SCC) using 17 cases of type B3 thymoma, 18 cases of TC and 12 cases of L-SCC. The results indicated that c-Kit and CD5 are very useful markers for TC, while GLUT-1, CLDN-1, p53 and Ki-67 are not. Thymic cortical microenvironmental marker cells, especially TCDMs, and thymic cortical epithelial cell-marker β5t are also useful for distinguishing TC from type B3 thymoma. Although none of these markers are adequate for making a distinction when used alone, the plural use of c-Kit, CD5, β5t thymic cortical environmental marker cells, c-Thys and TCDMs may therefore lead to a correct distinction between TC and type B3 thymoma or L-SCC. [J Clin Exp Hematop 53(1) : 9-19, 2013].

Comparative immunohistochemical analysis of IMP3, GLUT1, EMA, CD146, and desmin for distinguishing malignant mesothelioma from reactive mesothelial cells

OBJECTIVES

To identify useful biomarkers for differentiating between malignant mesothelioma (MM) and reactive mesothelial cells (RMCs).

METHODS

Formalin-fixed, paraffin-embedded (FFPE) tissues from 34 MM and 40 RMC samples were analyzed using immunohistochemistry, and the findings were compared.

RESULTS

Positive markers for MM included insulin-like growth factor 2 messenger RNA binding protein 3 (IMP3), glucose transporter 1 (GLUT1), epithelial membrane antigen (EMA), and CD146, which showed sensitivities of 94%, 85%, 79%, and 71% and specificities of 78%, 100%, 88%, and 98%, respectively. In sarcomatoid MM, EMA had significantly lower expression than did IMP3, GLUT1, and CD146 (P < .001). The areas under receiver operating characteristic curves were the highest for IMP3 (0.95), followed by GLUT1 (0.93). When the optimal cutoff points for IMP3 (30%) and GLUT1 (10%) were used, the sensitivity of IMP3 and GLUT1 for MM was 100%, and the specificity of both for MM was 95%.

CONCLUSIONS

The combination of IMP3 and GLUT1 is most appropriate for distinguishing MM from RMC using FFPE sections.

Glucose transporter 1 protein detected by enzyme-linked immunosorbent assay and immunocytochemistry: a useful diagnostic tool for malignant pleural effusions

BACKGROUND

Glucose transporter 1 (GLUT1) is a hallmark of metabolic change in cancer cells. The objective of this study was to determine the role of GLUT1 protein in diagnosing malignant pleural effusions by enzyme-linked immunosorbent assay (ELISA) and immunocytochemistry.

METHODS

In total, 82 pleural effusions were collected and classified as benign (n = 42), atypical (n = 8), or malignant (n = 32) based on cytologic diagnosis and etiology. GLUT1 protein levels in effusions were measured by ELISA. GLUT1 expression also was determined by immunocytochemistry using cell blocks.

RESULTS

GLUT1 levels were significantly higher in the malignant group compared with the benign group. Receiver operating characteristic curve analysis of benign and malignant pleural effusions for GLUT1 yielded an area under the curve of 0.77, with a value of 1355.87 pg/dL as the optimal threshold for distinguishing benign from malignant effusions. With the ELISA method, the sensitivity, specificity, and accuracy were 78.1%, 69%, and 73%, respectively. Malignant effusion cell blocks were positive for GLUT1 expression in 84.4% of cases with 100% specificity and 93.2% accuracy. With the combination of high GLUT1 protein levels (>10,000 pg/dL) and immunocytochemistry to detect malignant pleural effusions, the sensitivity and accuracy increased to 93.8% and 94.6%, respectively. The GLUT1 level measured by ELISA and the GLUT1 expression detected by immunocytochemistry were positively correlated. In atypical effusions, 3 cases (37.5%) had GLUT1 levels higher than the cutoff value.

CONCLUSIONS

The detection of GLUT1 protein by ELISA and immunocytochemistry may have utility in the diagnosis of malignant pleural effusions.

Well-differentiated papillary mesothelioma: a clinicopathological and immunohistochemical study of 18 cases with additional observation

AIMS

To present our experience with 18 cases of well-differentiated papillary mesothelioma (WDPM), with an emphasis on its relationship to adenomatoid tumour and multicystic mesothelioma.

METHODS AND RESULTS

Eighteen cases of WDPM were retrieved. Twenty cases of multicystic mesothelioma were selected for comparative study. The WDPM patients comprised 14 females and four males, with age ranging from 18 to 60 years (median 37 years). The tumour involved the abdominal or pelvic peritoneum (14 cases), the pleura (two cases), and the testicular tunica vaginalis (two cases). The majority of WDPMs were incidental findings during surgery for a wide variety of conditions. Histologically, 13 cases were consistent with classical WDPM. Two cases had a combined component of adenomatoid tumour, and three cases contained coexisting areas of multicystic mesothelioma. Among the multicystic mesothelioma cases, four had adenomatoid tumour-like foci present in the stroma. Immunohistochemically, all cases of WDPM and multicystic mesothelioma, as well as the coexisting combined components, were positive for mesothelial markers, with a low Ki67 index. This study also showed that WDPM was negative for epithelial membrane antigen and desmin.

CONCLUSIONS

The simultaneous occurrence of WDPM, adenomatoid tumour and multicystic mesothelioma in some cases suggested histogenetic relationships among these three less aggressive mesotheliomas.

Is galectin-3 antibody a useful marker in the diagnosis of malignant pleural mesothelioma?

Malignant pleural mesothelioma (MPM) is a challenging diagnosis characterized by the absence of real specific diagnostic markers. Positivity with the galectin-3 antibody was assessed by a cytoplasmic expression in 17 MPM. Fourteen cases expressed the galectin-3 antibody. The three negative cases consisted of epithelioid, biphasic, and sarcomatoid MPM. The 14 positive cases consisted of epithelioid MPM in 12 cases, sarcomatoid MPM in one case, and biphasic MPM in one case. In spite of our inability to prove the real diagnostic value of the galectin-3 antibody, our findings make us wonder about the implication of this antibody in the carcinogenesis of MPM.

Malignant peritoneal mesothelioma treated by cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: is GLUT1 expression a major prognostic factor? A preliminary study

PURPOSE

Diffuse malignant peritoneal mesothelioma (DMPM) is a rare primary peritoneal malignancy. Its prognosis has been improved by an aggressive locoregional treatment combining extensive cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Prognostic factors are currently poorly defined for this disease but are essential if treatment is to be standardized.

METHODS

Twenty-eight patients with DMPM, who were considered preoperatively to be candidates for CRS and HIPEC between June 1998 and August 2010 at our institution, were selected for this study. Medical records and histopathological features were retrospectively reviewed and 24 clinical, histological, and immunohistochemical parameters were assessed for their association with overall survival by univariate and multivariate analyses.

RESULTS

The following factors were significantly associated with overall survival by univariate analysis: predominant histological growth pattern in the epithelioid areas, nuclear grooves in the epithelioid areas, atypical mitoses, and calretinin and GLUT1 expression by immunohistochemistry in the epithelioid areas. Expression of the facilitative glucose transporter protein GLUT1 in the epithelioid areas was the only factor independently associated with overall survival by multivariate analysis.

CONCLUSIONS

GLUT1 expression appears to be an indicator of poor prognosis in DMPM. Standard histological classification of DMPM may not be adequate to select patients for aggressive locoregional treatments, such as CRS and HIPEC. Multicenter validation of the prognostic factors identified in this preliminary study is needed to refine patient selection for potential cure.

Unusual presentation and location pleural malignant mesothelioma

Pleural malignant mesothelioma is an uncommon tumour of the thorax. We report two cases: a patient with atypically isolated location of the tumour at the right hilum and a young female patient. The histopathological and radiological features are reviewed with reference to relevant literature.

Multilocular mesothelial proliferation involving the skin of the umbilicus

Multilocular mesothelial proliferation (MMP) is a rare lesion that mainly arises from the peritoneal mesothelium. Most often, it occurs in women of reproductive age, with a history of abdominal surgery, endometriosis, or pelvic inflammatory disease. We describe an unusual case of a 73-year-old woman affected by a large MMP, which involved the skin and presented clinically as a cutaneous mass. To the best of our knowledge, MMP involving the umbilicus has never been reported in a peer-reviewed literature.

Diagnostic usefulness of p16/CDKN2A FISH in distinguishing between sarcomatoid mesothelioma and fibrous pleuritis

The distinction between sarcomatoid mesothelioma and fibrous pleuritis is difficult based on histology, especially when the amount of tumor tissue examined via biopsy is small and immunohistochemical examination is inconclusive. We studied the usefulness of deletion of p16 with fluorescence in situ hybridization (FISH) and p16 hypermethylation with polymerase chain reaction for the diagnosis and prognosis of malignant pleural mesothelioma (MPM). We analyzed 50 MPMs, including 22 sarcomatoid mesothelioma cases and 10 fibrous pleuritis cases. We set the cutoff value of homozygous deletion pattern as 14.4% based on FISH signaling patterns using samples of fibrous pleuritis. The percentage of homozygous deletion pattern was higher than 14.4% in 55.6% of the epithelioid mesotheliomas (10/18) and in all of the sarcomatoid mesotheliomas (22/22). Methylation of p16 was observed in 7 (20.6%) of 34 informative cases. p16 FISH analysis can be a reliable test for distinguishing between sarcomatoid mesothelioma and fibrous pleuritis and a prognostic factor for MPM.

CD147 immunohistochemistry discriminates between reactive mesothelial cells and malignant mesothelioma

Malignant mesothelioma (MM) is a rare form of cancer. Its histopathological diagnosis is very difficult, as it exhibits a number of different appearances that can be misinterpreted as metastatic invasion or atypical hyperplasia. Thus, there is an urgent need to identify adequate markers to distinguish between benign and malignant cells, allowing the implementation of appropriate therapies and, possibly, specific directed therapies. MM, like other tumors, show an increase in glucose uptake, due to high rates of glycolysis, inducing an intracellular overload of acids. In this context, monocarboxylate transporters (MCTs) emerge as important players, by mediating the transmembranar co-transport of lactate with a proton, thereby, regulating pH and allowing continuous glycolysis. Importantly, proper MCT expression and activity depend on its co-expression with a chaperone, CD147, which is associated with poor prognosis in cancer. Twenty-two samples including reactive mesothelial cells, MM, and atypical mesothelial hyperplasias were evaluated for immunoexpression of MCT1, MCT4, and CD147. Expression of these proteins was compared with GLUT1 as a new promising marker for MM. Although MCT isoforms were not differentially expressed in the two types of cytological specimens, CD147, as GLUT1, was almost exclusively expressed in MM. Both MCT1 and MCT4 are not able to discriminate between mesothelial reactive cells and mesothelial malignant cells, while CD147 was able to distinguish these two proliferations. If confirmed, besides being a good marker for identification of MM, CD147 may also be a target for therapeutical strategies in this rare type of tumor.

Guidelines for pathologic diagnosis of malignant mesothelioma: 2012 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 in the field contributed to this update. Reference material includes peer-reviewed publications and textbooks.

CONCLUSIONS

There was consensus opinion regarding (1) distinction of benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiation of epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas, and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid mesothelioma, (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 used is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Immunohistochemical panels should contain both positive and negative markers. It is recommended that immunohistochemical markers 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 membranous markers). These guidelines are meant to be a practical reference for the pathologist.