Mesothelin

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

Mesothelin is a cell surface glycoprotein expressed by mesothelial cells and epithelioid mesothelioma. It is also positive in nonmucinous ovarian carcinoma (such as serous) and in pancreatic ductal carcinoma. It is much less specific than other mesothelioma markers, such as calretinin, WT-1, and podoplanin, as it is positive in adenocarcinomas from several sites, including a significant subset of lung adenocarcinoma. It is, however, rather sensitive, and a negative staining for mesothelin may be an indication AGAINST epithelioid mesothelioma.