Mesothelioma vimentin

Abnormal tissues The antibody labeled 17/20 sarcomas, 16/18 melanomas, 4/4 meningeomas, and 3/3 schwannomas, and was the sole intermediate filament present in these tumours. In addition, variable percentages (10 to 57 percent) of carcinomas, neuroendocrine carcinomas, neuroblastomas, thymomas and mesotheliomas were positive with the antibody. With the exception of the neuroblastomas, cytokeratin was coexpressed with vimentin in these tumours. Among adenocarcinomas, more than 50 percent of papillary carcinomas of the thyroid as well as renal, endometrial, ovarian and lung carcinomas were labeled by the antibody and coexpressed keratins and vimentin. 

Epithelial and sarcomatoid mesotheliomas are usually vimentin positive... 

Although malignant mesotheliomas are usually regarded as tumors of the peripheral pleurae or the peritoneum, they also are seen in the mediastinum, where they likely originate from hilar reflections of the pleural surfaces. The immunophenotype of mesothelioma features keratin reactivity in all of its histologic variants, including the purely epithelioid form, and the same is potentially true of calretinin, WT-1, and podo-planin. " Vimentin coexpression also may be seen in roughly 50% of mesothelioma cases, and there is... 

KER, keratin (mixture of monoclonal antibodies) EMA, epithelial membrane antigen VIM, vimentin CALRET, calretinin DES, desmin MSA, muscle-specific actin AFP, alpha fetoprotein SYN, synaptophysin CCA, chromogranin A MESOTH, mesothelioma SCYST, spindle cell yolk sac tumor LMS, leiomyosarcoma SPCCA, spindle cell carcinoma (either primary or metastatic) SYNSC, synovial sarcoma SPCNC, spindle cell neuroendocrine carcinoma FS, fibrosarcoma MFH, malignant fibrous histiocytoma. 

These authors use a battery of antibodies to evaluate mesothelial proliferative lesions, including reactive and neoplastic processes. Keratin antibodies, with the exception of CK5/6, are generally not used to differentiate an epithelial mesothelioma from another neoplasm or from a reactive process, but are used to identify the extent of a neoplastic or reactive mesothelial cell process. The antibodies we use to differentiate a well or moderately well differentiated epithelial mesothelioma from a pulmonary adenocarcinoma or nonpulmonary adenocarcinoma include AE1/AE3 cytokeratin, CK5/6, CK7, CK20, vimentin, EMA, EIBME-1, calretinin, mesothe-lin, WTl, D2-40, caldesmon, CEA, LeuMl, B72.3, BerEP4, and TTE-1. 

Most sarcomatoid mesotheliomas express keratin (usually low molecular weight keratin), vimentin, and frequently muscle-specihc/alpha actin. In our experience, a relatively small percent (10% to 20%) of sarcomatoid mesotheliomas express calretinin, and most sarcomatoid mesotheliomas do not express cytokeratin 5/6. Most sarcomatoid mesotheliomas express CK7, often intensely. In our experience, sarcomatoid mesotheliomas (and tumors with which they may be confused) do not express the negative markers used to evaluate potential epithelial mesotheliomas, including CEA, LeuMl, B72.3, BerEP4, BG8, and TTF-1. Therefore, we would not include these antibodies in a screen of a malignant spindle cell proliferative lesion of the pleura. 

Rare sarcomatoid mesotheliomas show heterologous differentiation composed of fat (Figs. 12.52 and 12.53). The immunohistogram of a sarcomatoid mesothelioma is shown in Figure 12.54. The most important immunohistochemical finding in sarcomatoid mesothelioma is coexpression of keratin and vimentin. 

As mesotheliomas become more poorly differentiated such as those we refer to as transitional, they usually only express broad-spectrum keratin and vimentin. 

Pleomorphic mesotheliomas exist and are composed of pleomorphic epithelioid and sarcomatoid cells. Occasional multinucleated macrophage giant cells are associated with the tumor cells. Pleomorphic mesotheliomas need to be differentiated from pleomorphic carcinomas of the lung. In most instances, pleomorphic mesotheliomas express pan cytokeratin and vimentin. 

FIGURE 12.57 This pseudomesotheliomatous epithelioid hemangioendothelioma was initially diagnosed as an adenocarcinoma and then as an epithelial mesothelioma. In this case, the neoplastic cells expressed keratin and endothelial cell markers CD31, factor VIII antigen, and vimentin. X 400. 

Chttrg A. Immrmohistochemical staining for vimentin and keratin in malignant mesothelioma. Am J Surg Pathol. 1985 9 360-365. 

Jasani B, Edwards RE, Thomas ND, et al. The use of vimentin antibodies in the diagnosis of malignant mesothelioma. Virch Arch A Pathol Anat. 1985 406 441-448. 

Mullink H, Henzen-Logmans SC, Alons-van Kordelaan JJM, et al. Simultaneous immtmoenzyme staining of vimentin and cytokeratins with monoclonal antibodies as an aid in the differential diagnosis of malignant mesothelioma from pulmonary adenocarcinoma. Virch Arch B Pathol Anat. 1986 42 55-65. 

ICC has proved most practical in the identification of melanoma. The tumor cells are immunoreactive for HMB45 (anti-melanoma), S-100 protein, and other melanoma markers. Vimentin, while positive in melanomas, is also positive in mesotheliomas, sarcomas, and some carcinomas. Malignant melanoma cells are immunoreactive for HMB45 and Melan-A in 60% to 80% of melanomas. Cytokeratin immunoreactivity has been reported in malignant melanoma in 1% to 27% of cases, but immunostaining in these cells is usually weak and focal (Fig. 21.14)." ... 

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