Types of tests to diagnose Mesothelioma
There are three types of Mesothelioma Cancer. These include Pleural, Peritoneum and Pericardial Mesothelioma. We will discuss diagnostic tests for each of these types.
Pleural Mesothelioma. Since asbestos fibers are very fine, they can easily make there way in the air we breathe into our lungs. Once in the lung they settle in the parenchyma of the lung and start to grow the pleura that later turns into malignant mesothelial plaques.
The pleura are the membrane that anchors the lungs to the chest cavity. It is a double cell layered membrane. The outer layer of this membrane, called the parietal pleura, is what forms the lining of the lung against the chest cavity. The inner layer, called visceral pleura surrounds the lung itself. These layers are filled with a fluid, which helps them to slide over each other as we breathe air in and out.
In the progression of Mesothelioma cancer, these delicate pleurla membranes began to thicken with cancer cells and press against the lungs. A fluid is then secreted by the malignant Mesothelioma cells, which is called pleural effusion. This pleural effusion can also collect between the two layers, which cause problems in breathing, and other complications between the visceral and parietal pleurae.
A second type of Mesothelioma is Peritoneum Mesothelioma. This occurs when the asbestos fibers attach and grow in the membranes surrounding the abdominal organs. A collection of a fluid called ascites attaches in the abdominal cavity causing it to swell. It is believed, though not yet proven that asbestos fibers are then transported to the abdomen and its organs by the lymphatic system. They could possibly be deposited in the stomach through saliva which has been contaminated with asbestos fibers.
The third and most rare type of Mesothelioma is Pericardial Mesothelioma. It only occurs in about 5% of all diagnosed Mesothelioma cases. Like other types of Mesothelioma cancer, it also is caused by inhalation of asbestos dust and fibers. The Pericardial Mesothelioma is when the cancer in the chest cavity which protects the heart. This cavity is the pericardium. It provides continuous lubricating cells to the heart so that it can move properly to do all its appropriate activity. As the cancer grows and spreads in this area, it threatens other areas, (i.e. lungs and abdomen) but it also destroys the heart muscle and tissues, which is very hazardous and usually fatal to the patient.
Besides a physical exam and patient history, x-rays of the chest and lungs, and lung function tests are given. The x-rays can reveal thickening in the pleural area, a common symptom of asbestos exposure. Doctors then also follow this up with CAT (Computed Tomography) scan or an MRI. (Magnetic Resonance Imaging)
If large amounts of fluid are found, the abnormal cells may be discovered by cytology. That is aspirating pleural fluid with a syringe. The absence of malignant cells on a cytology does not completely rule out Mesothelioma, but makes it more likely that the patient may have tuberculosis or regular heart failure.
If the plaque or cytology shows positive for cancer, a biopsy is done to confirm the diagnosis of Mesothelioma. The doctor takes a sample of tissue and exams it under a microscope. The specialist that does this in called a histopathologist.
Biopsies are done in different ways depending on where the abnormal cells are located. A thoracoscopy is used when the cancer is in the chest. The doctor makes a small cut through the chest where the doctor inserts a thin, lighted tube. This tube, called a thoracoscope goes between two ribs. This tool allows the doctor to look inside the chest and get the tissue samples they need.
When the cancer is in the abdomen, a laparoscopy is performed. The doctor makes an opening in the abdomen and inserts a special instrument called a laparoscope into the abdominal cavity. Sometimes this procedure may not produce enough tissue; in that case, more intrusive, extensive diagnostic surgery is performed.
Is there a universal screening that can predict if someone will develop Mesothelioma in the future? Currently no, however, some research suggests that the serum osteopontin level might be useful in screening people who are at risk for Mesothelioma. The level of a soluble mesothelin-related protein is higher in the serum of approximately 75% of patients that have been diagnosed.