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

Utility of Glucose Transporter 1 in the Distinction of Benign and Malignant Thoracic and Abdominal Mesothelial Lesions

Context.—Malignant mesothelioma, of either peritoneum or pleura, is an uncommon cancer. The diagnosis is often difficult to make, in part because of the overlapping morphology of reactive and malignant mesothelial cells. Glucose transporter 1 (GLUT-1) is a glucose transporter typically found on erythrocytes, which is aberrantly expressed in various carcinomas. It has recently been reported as specific and sensitive in discriminating malignant pleural mesothelioma from reactive hyperplasia. The application of GLUT-1 staining in peritoneal mesothelioma has not been fully explored.

Objective.—To determine if GLUT-1 staining is helpful in distinguishing abdominal mesotheliomas from benign, reactive mesothelial lesions and to further study its utility in the thorax.

Design.—Tissue microarrays containing 135 abdominal malignant mesotheliomas and 30 malignant pleural mesotheliomas were stained with an antibody to GLUT-1, as were 56 reactive mesothelial lesions.

Results.—The overall sensitivity and specificity for GLUT-1 in mesothelioma was 53% and 98%, respectively. The sensitivity in epithelioid malignant mesothelioma was 49% and in sarcomatoid/biphasic malignant mesothelioma, 66%. In the thorax, the sensitivity was 50% and in the abdomen it was 54%. The positive predictive value of GLUT-1 immunoreactivity was 98% and the negative predictive value was 40%.

Conclusion.—Glucose transporter 1 staining of thoracic mesotheliomas showed high specificity but lower sensitivity than previously reported. Abdominal malignant mesotheliomas showed similar results. Because of low sensitivity, only positive staining is informative. In both sites, the utility of the stain was limited by nonspecific staining (eg, in necrotic areas) as well as bright labeling of erythrocytes and occasional lymphoid elements. Despite these limitations, GLUT-1 can help differentiate malignant mesothelioma from reactive benign mesothelium.

Immunohistochemistry and Molecular Diagnostics of Pleural Malignant Mesothelioma

Context.—The pathologic approach to pleural-based lesions is stepwise and uses morphologic assessment, correlated with clinical and imaging data supplemented by immunohistochemistry (IHC), and more recently, molecular tests, as an aid for 2 main diagnostic problems: malignant mesothelioma (MM) versus other malignant tumors and malignant versus reactive mesothelial proliferations.

Objective.—To present the current knowledge regarding IHC and molecular tests with respect to MM diagnosis, and in particular, the differentiation of the epithelioid type of MM from carcinoma metastatic to the pleural cavity.

Data Sources.—A review of immunohistochemical features of 286 consecutive MMs from 459 cases of pleural pathology, diagnosed during routine practice from 2003 to 2009. A survey of biomedical journal literature from MedLine/PubMed (US National Library of Medicine) focused on MM and associated tissue-based diagnostic IHC markers and molecular tests.

Conclusions.—The search for a single diagnostic marker of MM has so far been discouraging, given the biologic and phenotypic tumor heterogeneity of MM. The use of antibody panels has gained unanimous acceptance especially in the differential diagnosis between MM and metastatic carcinoma, whereas the usefulness of IHC is more limited when dealing with spindle cell malignancies or distinguishing malignant from reactive mesothelium. A great degree of interlaboratory variability in antibody combinations and clone selection within diagnostic panels still exists. Current investigations aim at selecting the most suitable and cost-effective combination of antibodies by using novel statistical approaches for assessing diagnostic performance beyond the traditional measures of sensitivity and specificity.

Epithelioid Lesions of the Serosa

Context.—Diagnosing epithelioid serosal lesions remains a challenge because numerous different processes—primary or secondary, benign or malignant—occur in body cavities, some of which are very rare.

Objectives.—To review the newest literature and to describe the morphologic criteria and immunohistochemical markers that are useful for distinguishing epithelioid serosal lesions.

Data Sources.—Previously published literature concentrating on the newest research findings. Earlier reviews are principally referred to for established diagnostic criteria.

Conclusions.—Immunohistochemistry with a panel of antibodies has made the diagnosis of epithelioid serosal lesions very reliable. When deciding on antibodies used in differential diagnosis, it is important to consider tumor location, clinical and radiologic information, and morphologic features. Immunohistochemistry is less useful in the differential diagnosis of benign versus malignant mesothelial lesions. The diagnosis of benign versus malignant mesothelial proliferations still relies on the histologic criteria of invasion.

Pathological and molecular biological approaches to early mesothelioma

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

Early stages of mesothelioma, screening and biomarkers

The early diagnosis of mesothelioma is notoriously difficult, both from a clinical and pathological perspective. Patients often undergo several medical investigations without definitive diagnosis. The discovery of biomarkers that can be assessed in pleural effusions, histological samples, and serum may assist with the difficult early diagnosis of mesothelioma. In this chapter we focus on those markers that have been examined in the setting of either early diagnosis of mesothelioma in symptomatic individuals or that have been proposed as suitable for screening of asbestos-exposed individuals, with an emphasis on cytology and histology.

Multimodality Imaging Review of Malignant Pleural Mesothelioma Diagnosis and Staging

Early diagnosis and accurate disease staging in patients with malignant pleural mesothelioma (MPM) are essential in classifying such patients into prognostic subgroups to allow delivery of stage-specific therapies. This review addresses the current status of multimodality imaging in the diagnosis and staging of MPM. Clinical, research, and future directions in computed tomography (CT), magnetic resonance imaging, and PET/CT diagnosis and staging of MPM are discussed, including the use of novel PET probes. The article concludes with important take-home messages summarized as the pearls and pitfalls of each diagnostic modality in the diagnosis and staging of patients with MPM.

The diagnostic utility of p16 FISH and GLUT-1 immunohistochemical analysis in mesothelial proliferations

Two promising ancillary tests used in the diagnosis of mesothelioma include GLUT-1 immunohistochemical analysis and fluorescence in situ hybridization (FISH) testing for the p16 deletion. This study compared the diagnostic usefulness of p16 FISH and GLUT-1 immunohistochemical analysis in the diagnosis of mesothelial proliferations in 158 cases with a diagnosis of benign (45.4%), atypical (10.4%), or malignant/mesothelioma (44.2%). Of the 70 benign cases, none had a deletion of p16 and 5 cases (7%) were positive for GLUT-1. Of the 68 mesotheliomas, 40 (59%) had a deletion of p16 (sensitivity, 59%; specificity, 100%) and 27 (40%) were positive for GLUT-1 (sensitivity, 40%; specificity, 93%). GLUT-1 showed lower sensitivity in pleural (56% vs 70%) and peritoneal (29% vs 51%) mesotheliomas (P = .004). Our results demonstrate that p16 FISH is a more sensitive and specific test than GLUT-1 immunohistochemical analysis and can be a more reliable ancillary tool to support the diagnosis of mesothelioma.

GLUT-1 expression in pancreatic neoplasia: implications in pathogenesis, diagnosis, and prognosis

OBJECTIVES

GLUT-1 has been found to have an important role in the upregulation of various cellular pathways and implicated in neoplastic transformation correlating with biological behavior in malignancies. However, literature regarding the significance of GLUT-1 expression in pancreatic neoplasia has been limited and controversial.

METHODS

Immunohistochemical expression of GLUT-1 was tested in a variety of pancreatic neoplasia including ductal adenocarcinomas (DAs), pancreatic intraepithelial neoplasms (PanINs), intraductal papillary mucinous neoplasms (IPMNs), and serous cystadenomas.

RESULTS

There was a progressive increase in the expression of GLUT-1 from low- to higher-grade dysplastic lesions: All higher-grade PanINs/IPMNs (the ones with moderate/high-grade dysplasia) revealed noticeable GLUT-1 expression. Among the 94 DAs analyzed, there were minimal/moderate expression in 46 and significant expression in 24 DAs. However, all 4 clear-cell variants of DAs revealed significant GLUT-1 immunolabeling, as did areas of clear-cell change seen in other DAs. Moreover, all 12 serous cystadenomas expressed significant GLUT-1. GLUT-1 expression was also directly correlated with DA histological grade (P = 0.016) and tumor size (P = 0.03).

CONCLUSIONS

GLUT-1 may give rise to the distinctive clear-cell appearance of these tumors by inducing the accumulation of glycogen in the cytoplasm. Additionally, because GLUT-1 expression was related to histological grade and tumor size of DA, further studies are warranted to investigate the association of GLUT-1 with prognosis and tumor progression.

Adenomatoid tumors of the female and male genital tract. A comparative clinicopathologic and immunohistochemical analysis of 47 cases emphasizing their site-specific morphologic diversity

Adenomatoid tumors (ATs) are uncommon benign mesothelial tumors with a predilection for the genital tract. We reviewed 47 ATs diagnosed at our institutions during 10-year period. Thirty tumors (64%) originated in the female (21 uterine, 8 tubal, and 1 ovarian) and 17 (36%) in the male (9 epididymal and 8 testicular) genital tract. The median age for females and males was 47.5 and 51 years, respectively. While 83% of tumors in females were incidental findings in resections for unrelated diseases, 94% of male lesions presented as clinical masses leading to surgery. The median size was 2, 1, and 0.5 cm for uterine, epididymo-testicular, and tubo-ovarian lesions, respectively. Architecturally, the microcystic/angiomatoid pattern was the most frequent (32/47; 68%), followed by combined microcystic/trabecular (26/47; 55%) and retiform/adenoid (15/47; 32%) pattern. The trabecular/solid (6%) and macrocystic (4%) patterns were uncommon. However, 57% of cases revealed ≥2 growth patterns. Taken by anatomic site, 20 of 21 uterine cases were at least focally microcystic but none was retiform. In contrast, the retiform pattern dominated in male genital tract tumors (12/17; 71%). Immunohistochemistry showed expression of calretinin (36/36) and D2-40 (30/30) and lack of CD34 (0/30) and PAX8 (0/32). GLUT-1 was expressed in 11/11 male genital tract tumors but in none of the microcystic uterine lesions. Estrogen and progesterone receptor expression was weak and focal (two and three uterine cases, respectively). None stained for the androgen receptor. Our study illustrates the great site-specific morphological diversity of ATs emphasizing their wide site-dependent differential diagnosis.

FISH assay development for the detection of p16/CDKN2A deletion in malignant pleural mesothelioma

Aims

To develop a fluorescence in-situ hybridisation (FISH) assay for detecting p16/CDKN2A deletion on paraffin tissue sections for use as an ancillary test to distinguish reactive from malignant mesothelial proliferations.

Method

Dual-colour FISH for p16/CDKN2A and chromosome 9 (CEP-9) was performed on 11 benign mesothelial proliferations and 54 malignant pleural mesothelioma (MPM) cases to establish cut-off values for p16/CDKN2A deletion. A third MYC probe was used to verify cases showing homozygous deletion. Eight equivocal biopsies were used for assay testing.

Results

Cut-off values for p16/CDKN2A deletion were calculated based on FISH signalling patterns obtained from the benign controls (mean percent nuclei plus three standard deviations). Hemizygous deletion was defined as >44% of nuclei showing the hemizygous (one p16/CDKN2A, two CEP-9 signals) or >15% of nuclei showing the monosomy (one p16/CDKN2A, one CEP-9 signal) deletion patterns. None of the benign cases showed a homozygous deletion pattern (no p16/CDKN2A, at least one CEP-9 signal). In the malignant cases, the percentage of nuclei showing homozygous deletion ranged from 1% to 87%. Therefore, the cut-off value for homozygous deletion was defined as >10%. P16/CDKN2A deletion was detected in 61% (33/54) of MPM cases. Among the equivocal biopsies, four showed homozygous and one showed hemizygous p16/CDKN2A deletion. Age over 60 years, asbestos exposure and p16/CDKN2A deletion were associated with a worse prognosis.

Conclusion

Distinction between benign and malignant mesothelial proliferations can be diagnostically challenging. FISH for p16/CDKN2A deletion is a useful test for confirming the diagnosis of MPM.

Immunocytochemistry of CD146 is useful to discriminate between malignant pleural mesothelioma and reactive mesothelium

Malignant pleural mesothelioma is a refractory tumor with poor prognosis associated with asbestos exposure. Pleural effusion is frequently observed in patients with malignant pleural mesothelioma, and cytological analysis is effective to detect malignant pleural mesothelioma. However, cytological discrimination between malignant pleural mesothelioma and reactive mesothelium is often difficult. Increased expression of CD146, a cell adhesion molecule, has been reported to be closely associated with an advanced stage of malignant melanoma, prostate cancer, and ovarian cancer. In this study, to evaluate the diagnostic utility of CD146 for discrimination between malignant pleural mesothelioma and reactive mesothelium, we examined immunocytochemical expression of CD146 in malignant pleural mesothelioma and reactive mesothelium using two clones of CD146 antibody, OJ79 and EPR3208, on smear specimens of effusion fluids. Immunocytochemical stains were semiquantitatively scored on the basis of immunostaining intensity (0, negative; 1, weak positive; 2, moderate positive; and 3, strong positive). CD146 expression was detected in 15 of 16 malignant pleural mesothelioma with median immunostaining score of 3 by OJ79, and in 19 of 21 malignant pleural mesothelioma with median immunostaining score of 2 by EPR3208. Strong immunoreactivity of CD146 was observed at the apposing surfaces of cell-cell interactions on the plasma membrane of mesothelioma cells. In addition, one OJ79-negative case of malignant pleural mesothelioma was positive for CD146 by EPR3208 and two EPR3208-negative cases of malignant pleural mesothelioma were CD146 positive by OJ79, showing that all 23 malignant pleural mesothelioma cases were positive for CD146 by either OJ79 or EPR3208. On the other hand, CD146 expression was undetectable in all reactive mesothelium cases by OJ79 and EPR3208. The sensitivity of OJ79 and EPR3208 was 94 and 90%, respectively, and the specificity was 100% for both clones. We propose that CD146 is a sensitive and specific immunocytochemical marker enabling differential diagnosis of malignant pleural mesothelioma from reactive mesothelium.

Occupational toxicology of asbestos-related malignancies

INTRODUCTION

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

METHODS

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

ASSESSMENT OF EXPOSURE

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

CONCLUSIONS

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

Mesothelioma of the tunica vaginalis: a series of eight cases with uncertain malignant potential

Well-differentiated papillary mesotheliomas have rarely been reported to involve the testis tunica vaginalis. While the classic histology of the originally described well-differentiated papillary mesotheliomas consisted of papillae lined by a single layer of bland cuboidal cells, more complex architectural patterns have been described. This report details our experience with eight paratesticular mesotheliomas that span the histological spectrum from classic well-differentiated papillary mesotheliomas to those with more complex patterns. We attempt to determine whether there are prognostic or immunohistochemical differences between these lesions and 28 diffuse malignant mesotheliomas. All cases had papillary/tubulopapillary in addition to more complex architectures (cribriform, condensed) and none showed evidence of invasion. Mitotic figures were present in seven cases and averaged 2.1 mitosis per 50 h.p.f. All cases showed <or=1% of positive cells staining for Ki-67 and p53, and only one case stained positive for GLUT-1 in comparison with 50% positivity for GLUT-1 in diffuse mesotheliomas. Of five patients with follow-up information of more than 1 year, three patients were alive at 2, 3 and 9 years, and two died of unknown causes at 5 and 47 years, suggesting that these lesions behave more indolently than typical malignant mesotheliomas of the tunica vaginalis. If these cases were diffuse malignant mesotheliomas, one would have expected at least some of the patients to have died of disease within a couple of years after diagnosis. However, detailed and long-term follow-up were not sufficiently available to reach definitive conclusions on the true biological behavior of these tumors. The morphological continuum noted between our cases and classic well-differentiated papillary mesotheliomas, combined with their immunohistochemical profile and indolent behavior, contrasts with that of diffuse malignant mesotheliomas. We propose that these tunica vaginalis mesotheliomas, which are more complex than the classic well-differentiated papillary mesotheliomas, and yet are not overtly histologically malignant, be classified as 'mesotheliomas of uncertain malignant potential'.

Secretion of intelectin-1 from malignant pleural mesothelioma into pleural effusion

Background:

Malignant pleural mesothelioma (MPM) is a rare but fatal tumour. Although most MPM patients show pleural effusion at even the early stage, it is hard to diagnose as MPM at the early stage because a sensitive and reliable diagnostic marker for MPM has not been found in plasma or pleural effusion.

Methods:

In this study, we investigated whether intelectin-1 was specifically contained in MPM cells and the pleural effusion of MPM patient by immunohistochemistry, western blotting, and enzyme-linked immunosorbent assay.

Results:

Malignant pleural mesothelioma cell lines, but not lung adenocarcinoma cell lines, secreted intelectin-1. In immunohistochemistry, epithelioid-type MPMs, but neither pleura-invading lung adenocarcinomas nor reactive mesothelial cells near the lung adenocarcinomas, were stained with anti-intelectin antibodies. Pleural effusion of MPM patients contained a higher concentration of intelectin-1 than that of lung cancer patients.

Conclusion:

These results suggest that detection of intelectin-1 may be useful for a differential diagnosis of epithelioid-type MPM in immunohistochemistry and that a high concentration of intelectin-1 in pleural effusion can be used as a new marker for clinical diagnosis of MPM.

Disruption of the blood brain barrier by brain metastases of triple-negative and basal-type breast cancer but not HER2/neu-positive breast cancer

BACKGROUND

Generally, the blood-brain barrier (BBB) of brain metastasis was thought to be disrupted.

METHODS

We retrospectively performed immunohistochemical staining for glucose transporter 1 (GLUT1) and breast cancer resistance protein (BCRP) to evaluate the status of the BBB in resected brain metastases. Associations between expression of GLUT1 and/or BCRP and the immunohistochemical profiles of breast cancers, such as the statuses of hormone receptors, human epidermal growth factor receptor 2 (HER2/neu), and a basal-type marker (cytokeratin 5/6, HER1), were also analyzed.

RESULTS

The study included 29 breast cancer patients with brain metastasis who had undergone brain tumor resections. Among the 29 patients, there was no expression of GLUT1 and BCRP in the intratumor microvessels of 9 (32%) and 11 (38%) patients, respectively. There was no expression of both GLUT1 and BCRP in 8 patients (28%). The expression of GLUT1 was significantly associated with that of BCRP (P < .001). A positive correlation was observed between the expression of GLUT1 and/or BCRP and brain metastases of HER2/neu-positive breast cancer (P = .012), while a negative correlation was observed between the expression of GLUT1 and/or BCRP and brain metastases of triple negative or basal-type breast cancer (P = .014 and P = .003 for triple negative and basal-type, respectively).

CONCLUSIONS

Brain metastases of triple negative or basal-type breast cancers may often disrupt the BBB, whereas brain metastases of HER2/neu-positive breast cancer tend to preserve the BBB.

Benign and Malignant Mesothelial Proliferation

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

IMP3/L523S, a novel immunocytochemical marker that distinguishes benign and malignant cells: the expression profiles of IMP3/L523S in effusion cytology

Differentiating reactive mesothelial cells from metastatic carcinoma and malignant mesothelioma is critical in effusion cytology. Numerous immunohistochemical/cytochemical reports use various antibodies in effusion samples, and most antibodies differentiate metastatic adenocarcinoma from malignant mesothelioma, but no antibodies help distinguish malignant mesothelioma from reactive mesothelial cells. A mouse monoclonal antibody (IMP3/L523S) against KOC is a 580-amino acid oncofetal RNA-binding protein containing 4 K homology domains. IMP3/L523S has been identified in several human malignant tumors. The immunocytochemical staining profile of IMP3 was determined in 95% alcohol-fixed cytologic effusion specimens. A total of 229 cases of pleural and peritoneal effusion cytospecimens were evaluated for the study, including 39 benign effusions with reactive mesothelial cells and 190 metastatic malignant effusions. IMP3 immunoreactivity was observed in 2 (5.1%) of 39 cases of reactive mesothelial cells, 138 (72.6%) of 190 cases of malignant effusion, 4 (36.4%) of 11 cases of malignant mesothelioma, 106 (75.7%) of 140 cases of metastatic adenocarcinoma, and 8 (100%) of 8 cases of squamous cell carcinoma. The overall specificity for the diagnosis of malignancy was 94.9%, whereas the sensitivity was 72.6%. In the peritoneal effusions, the sensitivity for the diagnosis of metastatic adenocarcinoma to distinguish reactive mesothelial cells was 92.3%. In conclusion, IMP3 staining is present in many carcinomas and is not a useful marker for distinguishing between carcinomas arising in different organs. However, the IMP3 antibody is a highly specific marker for malignant lesions, and thus, IMP3 staining is useful for distinguishing neoplastic cells from reactive mesothelial cells in effusion samples.

Immunohistochemical differential diagnosis between thymic carcinoma and type B3 thymoma: diagnostic utility of hypoxic marker, GLUT-1, in thymic epithelial neoplasms

There are only a few immunohistochemical markers that are useful for differentiating thymic carcinomas from type B3 thymomas. The purpose of this study is to examine the additional markers that would be useful for differentiating between thymic carcinoma and thymoma type B3. We performed a tissue microarray analysis of surgically resected thymic tumor specimens from 12 cases of thymic carcinoma, 7 cases of type B3 thymoma, and 68 cases of other types of thymoma. Immunostaining using 49 antibodies was scored based on staining intensity and the percentage of cells that stained positive. Seven proteins that were selected by the staining scores, namely, GLUT-1 (167 vs 4), CA-IX (110 vs 15), c-kit (162 vs 44), CD5 (33 vs 0), MUC-1 (54 vs 0), CEA (42 vs 0), and CK18 (110 vs 42), were significantly higher in the thymic carcinomas than in the type B3 thymomas. The staining sensitivity and specificity of the antibodies for thymic carcinoma were GLUT-1, sensitivity 72% and specificity 100%; CA-IX, 58 and 71%; c-kit, 72 and 85%; CD5, 33 and 100%; CK18, 58 and 71%; MUC-1, 25 and 100%; and CEA, 33 and 100%. Glucose transporter 1 (GLUT-1) is the best marker for thymic carcinoma because it had the highest sensitivity and specificity. Positive immunostaining for a combination of three markers, namely, GLUT-1, CD5, and CEA, enabled differentiation of thymic carcinoma with 91.6% sensitivity and 100% specificity. In conclusion, we identified GLUT-1 as an additional marker that will be useful for differentiating thymic carcinoma from type B3 thymoma, especially in biopsy specimens that have been crushed or are otherwise difficult to examine morphologically in thymic tumors.

Overexpression of GLUT-1 in the invasion front is associated with depth of oral squamous cell carcinoma and prognosis

OBJECT

Malignant cells show increased uptake, which is considered to be facilitated by glucose transporters (GLUTs). Increased GLUT-1 expression has been reported in many human cancers. We hypothesized that a oral squamous cell carcinoma, characterized by high frequency of lymph node metastasis, distant metastasis or local recurrences, was associated with GLUT-1 overexpression in invasion front.

METHODS

GLUT-1 immunostaining in invasion front was studied on 24 oral squamous cell carcinomas, and revealed the correlation with the clinical characteristics.

RESULT

The analysis showed that all oral squamous cell carcinoma patients and GLUT-1 expression correlated the depth of the tumors (P = 0.023 < 0.05). Furthermore the survival of patients who had overexpression of invasion front was significant shorter than that of patients with GLUT-1 weakly positive (P = 0.046 < 0.05). No significant association was noted between GLUT-1 immunostaining and either age, gender, subsites, tumor size, or lymph node status.

CONCLUSION

The present study shows that GLUT-1 served as a marker indicating that tumors with deep invasion tended to result in a worse prognosis in patients due to either lymph node metastasis, a recurrence of the primary lesion or distant metastasis.

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

CONTEXT

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

OBJECTIVE

To develop practical guidelines for the pathologic diagnosis of MM.

DATA SOURCES

A pathology panel was convened at the International Mesothelioma Interest Group biennial meeting (October 2006). Pathologists with an interest in the field also contributed after the meeting.

CONCLUSIONS

There was consensus opinion regarding (1) distinguishing 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) differentiating 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 differential 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. The International Mesothelioma Interest Group recommends that 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.

Expression of p-AKT characterizes adenoid cystic carcinomas of head and neck with a higher risk for tumor relapses

Background

Adenoid cystic carcinomas are rare tumors with an indolent clinical course, but frequent local relapses. The identification of tumors with a higher relapse risk seems to be interesting. Hence we investigated parameters of glucose metabolism, which were found associated with poor prognosis in other malignancies.

Methods

Specimen of 29 patients were investigated immunohistochemically with antibodies against p-AKT, TKTL-1 (transketolase-like 1), M2PK (M2 pyruvate kinase), and GLUT-1. Proliferation was investigated by staining with Ki67. The tumors were located at the major or minor salivary glands. Only the typical cribriform subtype was investigated. The initial tumor stage was pT1 or pT2.

Results

Expression of p-AKT was significantly (P = 0.036) associated with a higher relapse risk in multivariate analysis. Low expression of M2PK was non-significantly (P = 0.065) predictive for a higher risk. TKTL-1 and GLUT-1 were expressed in the majority of cases, albeit not associated with relapse risk.

Conclusion

Adenoid cystic carcinomas positive for p-AKT show a higher relapse risk. However, other parameters of glucose metabolism investigated here or proliferation (Ki67) were not predictive in this entity. Our findings demonstrate a possible background for therapeutic approaches targeting the inhibition of PI3K/AKT pathway.

Usefulness of EMA, GLUT-1, and XIAP for the cytologic diagnosis of malignant mesothelioma in body cavity fluids

We compared the effectiveness of epithelial membrane antigen (EMA) with 2 newly described markers, X-linked inhibitor of apoptosis protein (XIAP) and an isoform of glucose transporter (GLUT-1), in the distinction between malignant mesothelioma (MM) and benign effusion (BE) in body cavity fluids. Immunohistochemical studies were performed on cell block sections from 35 cases of histologically confirmed MM and 38 BEs, using antibodies to EMA, XIAP, GLUT-1 (GLUT-1m, monoclonal; GLUT-1p, polyclonal). Results were graded based on the percentage of cells staining: negative (0%), 1+ (<25%), 2+ (25%-49%), 3+ (50%-74%), and 4+ (75%-100%). The performance of each marker was compared using receiver operating characteristic curve analysis. EMA demonstrated the best accuracy, with an area under the curve of 0.91 as compared with XIAP (0.67), GLUT-1m (0.74), and GLUT-1p (0.80). Based on these findings, EMA is a better marker than XIAP or GLUT-1 for the diagnosis of MM.

Immunohistochemical expression of the glucose transporters Glut-1 and Glut-3 in human malignant melanomas and benign melanocytic lesions

Background

Reported data indicate that cancer cells have increased rates of glucose metabolism, as determined by 18FDG-PET imaging in patients with malignancies. The results of many studies have demonstrated that the expression of glucose transporters, especially Glut-1, is increased in a variety of malignancies. This study was undertaken to assess the differential expression of Glut-1 and Glut-3 by benign and malignant melanocytic lesions.

Methods

Immunohistochemical staining for Glut-1 and Glut-3 was performed on paraffin-embedded tissue sections prepared from melanocytic nevi (12 cases), Spitz nevi (12 cases) and primary cutaneous malignant melanomas (20 cases).

Results

We observed immunoreactivity for Glut-1 in all melanocytic nevi, 9 of the 12 Spitz nevi and in 9 of the 20 malignant melanomas, whereas Glut-3 was expressed in all the melanocytic lesions, both benign and malignant.

Conclusion

These findings indicate that the glucose transporters Glut-1 and Glut-3 play a role in the glucose metabolism of melanocytic cells. Glut-1 was present in the majority of benign nevi, whereas its expression was downregulated in 55% of malignant melanomas. Our results suggest that glucose transporter Glut-1 expression can significantly discriminate between human malignant melanoma and benign melanocytic nevi, and support the idea that additional mechanisms other than Glut-1 may contribute to glucose uptake in melanomas.

Diagnostic importance of 9p21 homozygous deletion in malignant mesotheliomas

Definitive diagnosis of malignant mesothelioma in small specimens can be extremely difficult based on morphology alone. Homozygous deletion of 9p21, the locus harboring the p16 gene, has been reported as the most common genetic alteration in malignant mesotheliomas. Recent studies demonstrated that this alteration may be useful for differentiating benign from malignant mesothelial proliferations in cytology specimens. The aim of this study was to evaluate the diagnostic utility of homozygous deletion of 9p21 assessed by fluorescence in situ hybridization (FISH) in mesothelial proliferations involving serosal surfaces in paraffin-embedded tissue. p16 protein immunoexpression was also explored as a potential diagnostic aid. FISH analysis demonstrated homozygous deletion of the 9p21 locus in 35 of 52 cases (67%) of pleural mesothelioma and in 5 of 20 cases of peritoneal mesothelioma (25%) (P<0.005). None of 40 cases of reactive pleural mesothelial proliferations showed p16 deletion (P<0.005). Loss of immunoexpression of p16 was observed in 71% of the peritoneal mesotheliomas, 40% of the pleural malignant mesotheliomas and 15% of the reactive mesothelial cells. Homozygous deletion did not correlate with p16 protein expression in any of the studied groups. Our study suggests that 9p21 homozygous deletion assessed by FISH on paraffin-embedded tissue may be helpful for differentiating between malignant mesotheliomas and reactive mesothelial proliferations. A discrepancy between p16 protein expression and homozygous deletion suggests that other molecular mechanisms may play a role in p16 protein expression in mesothelial proliferations.