How is a Diagnosis of Mesothelioma Done?
Magnification to Aid Detection/Recognition
Even with fluid samples from the area around the lungs, abdomen or heart, it is often difficult to diagnose mesothelioma. It is even hard to diagnose mesothelioma with tissue from biopsies. This is because mesothelioma cells are difficult to distinguish from several other types of cancer when viewed under the microscope. For example, pleural mesothelioma can resemble various types of lung cancer, and peritoneal mesothelioma can resemble various cancers of the ovaries. In recognition of this dilemna, special laboratory tests are often done to pinpoint mesothelioma amidst several possibilities.
These lab tests use special techniques to identify certain chemicals known to be present in mesotheliomas, and as importantly, known to be different than those present in cancer of the lung or ovary. The electron microscope may also be helpful in diagnosing mesothelioma. The electron microscope has a magnification power 100 times greater than the light microscope which is generally used in cancer diagnosis. This allows detection of the small parts of the cancer cells that distinguish mesothelioma from other types of cancer.
Distinguishing malignant mesothelioma from other forms is often a difficulty. The most favorable diagnostic tools presently remain the open pleural biopsy performed during thoracoscopy which allows for direct inspection of the inside of the chest, and provides information on the involvement of the other organs and any spread of disease. Less successful procedures are CT guided pleural biopsy, or blind pleural biopsy. In addition to the gross appearance of the tumor, pathologists often rely on a panel of histochemical and immunohistochemical stains to diagnose or exclude meosothelioma. Chemicals linked to the prognosis of mesotheliom are being studied. But it would take sometime before they are validated for general use.
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