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Mesothelioma DiagnosisDiagnosing mesothelioma is often difficult, because the symptoms are similar to
those of a number of other conditions. Diagnosis begins with a review of the patient's medical history. A history of exposure to asbestos
may increase clinical suspicion for mesothelioma. A physical examination is performed, followed by chest X-ray and often lung function
tests. The X-ray may reveal pleural thickening commonly seen after asbestos exposure and increases suspicion of mesothelioma. A CT (or CAT)
scan or an MRI is usually performed. If a large amount of fluid is present, abnormal cells may be detected by cytology if this fluid is
aspirated with a syringe. For pleural fluid this is done by a pleural tap or chest drain, in ascites with an paracentesis or ascitic drain
and in a pericardial effusion with pericardiocentesis. While absence of malignant cells on cytology does not completely exclude mesothelioma,
it makes it much more unlikely, especially if an alternative diagnosis can be made (e.g. tuberculosis, heart failure).
If cytology is
positive or a plaque is regarded as suspicious, a biopsy is needed to confirm a diagnosis of mesothelioma. A doctor removes a sample of
tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is
located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the
chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside
the chest and obtain tissue samples.
If the cancer is in the abdomen, the doctor may perform a laparoscopy. To obtain tissue for
examination, the doctor makes a small opening in the abdomen and inserts a special instrument into the abdominal cavity. If these procedures
do not yield enough tissue, more extensive diagnostic surgery may be necessary.
Doctors have begun testing the Mesomark assay which
measures levels of soluble mesothelin-related proteins (SMRPs) released by diseased mesothelioma cells. The procedure could diagnose
mesothelioma earlier than conventional methods thus improving the survival prospects for patients.
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What Is My Diagnosis?There are three types of mesothelioma. Pleural
mesothelioma is a cancer of the lining of the lung (pleura), peritoneal
mesothelioma is a cancer of the lining of the abdominal cavity (peritoneum), and pericardial
mesothelioma is a cancer of the lining surrounding the heart (pericardium). Sub-types (or cell types) of mesothelioma are epithelioid
(the most common, and considered the most amenable to treatment), sarcomatous (a much more aggressive form), and biphasic or mixed (a combination of both of the
other cell types).The structural appearance of cells under the microscope determine the cell or sub-type
of mesothelioma. Epithelioid is the least aggressive; sarcomatoid, the most aggressive. The biphasic or mixed cell type shows structural
elements of both of the other two.
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Epithelioid
mesothelioma tissue |
Sarcomatoid
mesothelioma tissue |
Biphasic
mesothelioma tissue |
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