Mesothelial markers

Calretinin and WTl are two most sensitive mesothelial markers with high specificity. 

Marchevsky evaluated sarcomatoid mesotheliomas and correctly pointed out that the diagnosis of sarcomatoid mesothelioma was particularly difficult as the sensitivity and specificity of mesothelial markers was considerably lower in these lesions than in malignant epithelial mesothelioma. Marchevsky correctly stated that immunostains for calretinin, thrombomodulin, and WTl were positive in fewer than 20% of sarcomatoid mesotheliomas. Marchevsky stated that immunostain-ing for AE1/AE3 keratin was the most helpful in that it showed staining in almost all cases of sarcomatoid... 

Attanoos RL, Dojcinov SD, Webb R, Gibbs AR. Anti-mesothelial markers in sarcomatoid mesothelioma and other spindle cell neoplasms. Histopathology. 2000 37 224-231. 

The highest sensitivity for adenocarcinomas can be achieved with the staining combination of negative mesothelial markers and positive adenocarcinoma markers (BG-8, MOC31, Ber-EP4, CEA, or B72.3). 

LeuMl with malignant mesothelioma has been reported as result of high hyaluronic acid content/ CD 15 did not gain popularity as a non-mesothelial marker owing to its low sensitivity as well as its low complementary value with other markers. 

Calretinin, a calcium-binding protein, is typically used as a marker for neural, mesothelial, or ovarian sex-cord... 

A variety of antibodies have been used to understand and help diagnose mesotheliomas. They can be divided into three main categories 1) antibodies that are relatively specific for mesothelial cells and mesotheliomas, which when positive serve as a positive marker for mesotheliomas 2) antibodies that show no reaction for mesothelial cells or mesotheliomas and when negative serve as a negative marker for mesotheliomas and 3) other antibodies that may react with mesothelial cells and mesotheliomas but are relatively nonspecific. 

Some epithelial mesotheliomas are composed of small cysts formed by uniform cuboidal mesothelial cells and associated numerous blood vessels (Fig. 12.68). This type of mesothelioma may be difficult to differentiate from a vascular neoplasm. The epithelial mesothelial cells may contain intracytoplasmic hemosiderin (Fig. 12.69). The immunophenotype of such neoplasms is identical to that of other epithelial mesotheliomas. The vascular proliferation may be related to an endothelial growth factor produced by neoplastic mesothelial cells.Adenomatoid tumors are localized benign mesothelial proliferations that most frequently occur in the epididymus and cornua of the uterus.Adenomatoid tumors have been identified in the adrenal gland and pancreas. These tumors are formed by uniform small cuboidal cells and can appear invasive. They express keratin and other markers of mesothelial cells and have the characteristic ultrastruc-tural features of mesothelial cells. Adenomatoid tumors have also been reported in the pleura. Hyperplastic... 

Barberis MCP, Faleri M, Veronese S, et al. Calretinin A selective marker of normal and neoplastic mesothelial cells in serous effusions. Acta Cytol. 1997 41 1757-1761. 

Hurlimann J. Desmin and neural marker expression in mesothelial cells and mesotheliomas. Hum Pathol. 1994 25 753-757. 

Acurio A, Atif Q, Gattuso P, et al. Value of immunohistochemical markers in differentiating benign from malignant mesothelial lesions. Mod Pathol. 2008 21 334A. 

X-linked inhibitor of apoptosis (XIAP) is a monoclonal antibody shown to be a useful marker for distinguishing malignant from benign groups of cells. XIAP is also demonstrated in a variety of adenocarcinomas (up to 54%). However, weak and focal staining is seen in mesothelial cells (up to 11%). 

Wilms tumor gene product (WTl) has been established as a good marker for mesothelial cells. Studies have also demonstrated that WTl is a highly sensitive and specific marker of serous carcinomas of ovarian surface epithelial origin (both ovarian and extra-ovarian). Mucinous and micropapillary breast carcinomas may express WTl and thus confound the distinction between breast carcinoma and metastatic ovarian serous carcinoma (Fig. 21.13). ° ... 

Hepatocyte nuclear factor-ip (HNF-ip) is a transcription factor that directly binds to DNA and is shown to be unregulated in ovarian clear cell carcinomas for unknown reasons. Mesothelial cells and non-clear cell adenocarcinomas are shown to be negative. A distinct nuclear staining is shown in clear cell carcinomas and is considered to be a positive result. HNF-ip is useful in peritoneal fluid cytology to distinguish clear cell carcinomas from other adenocarcinomas. Future studies are needed to evaluate the sensitivity and specificity of this marker in other cytology samples. 

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