Monday, October 29, 2007

Diagnosing mesothelioma

Diagnosing mesothelioma

As a first step in diagnosing the disease, the doctor may order an x-ray of the chest or abdomen or a CT (or CAT) scan or MRI may be performed. Although mesothelioma typically cannot be seen on an x-ray, the tumor often causes a pleural effusion, or fluid collection between the lung and chest wall. This abnormal finding is associated with shortness of breath and warrants clinical follow up. Lung function tests may also be completed.

The doctor may look inside the chest cavity with a special instrument called a thoracoscope. A cut will be made through the chest wall and the thoracoscope will be put into the chest between two ribs. This test, called thoracoscopy, is usually done in the hospital. Before the test, the patient will be given a local anesthetic (a drug that causes a loss of feeling for a short period of time). Some pressure may be felt, but usually there is no pain.

The doctor may also look inside the abdomen (peritoneoscopy) with a special tool called a peritoneoscope. The peritoneoscope is put into an opening made in the abdomen. This test is also usually done in the hospital. Before the test is done, a local anesthetic will be given.

If tissue that is not normal is found, the doctor will need to cut out a small piece and have it reviewed under a microscope to see if there are any cancer cells. This is called a biopsy. Biopsies are usually done during the thoracoscopy or peritoneoscopy.




Diagnosing mesothelioma is very difficult, and cases of mesothelioma misdiagnosed are unfortunately not uncommon. It is important to share your case history of work experience (especially in shipyards and at construction sites) and asbestos exposure potential with your physicians if you feel mesothelioma is a risk. Asbestos fibres can also be carried into the home on clothing, inadvertently exposing the deadly fibres, and the risk of mesothelioma, to family members.

A mesothelioma diagnosis is serious, but treatments are available. The chance of recovery (prognosis) depends on the size of the cancer, where the cancer is, how far the cancer has spread, how the cancer cells look under the microscope, how the cancer responds to treatment, and the patient's age. As with most types of cancer, early diagnosis is an excellent first step in fighting the disease.

Diagnosing 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.

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