Mesothelioma Diagnosis (2)

Mesothelioma is a rare form of cancer that develops from the protective lining which covers many of the body's internal organs, the mesothelium. It is mostly caused by exposure to asbestos. Its most common site is the pleura (outer lining of the lungs and internal chest wall), but it can also occur in the peritoneum (the lining of the abdominal cavity), the heart, the pericardium (a sac that surrounds the heart) or tunica vaginalis. Mesothelioma diagnosis is often difficult, because the symptoms are similar to those of a number of other conditions. If you are suffering from this disease, diagnosing starts with a review of your medical history. History of exposure to asbestos may increase your clinical suspicion for mesothelioma. A physical examination is carried out, followed by chest X-ray and often lung function tests. The X-ray may show pleural thickening, commonly observed after asbestos exposure and increase suspicion of mesothelioma. An MRI or a CT scan is usually performed. If there is a large amount of fluid, abnormal cells may be detected by cytopathology, if this fluid is aspirated with a syringe. For pleural fluid, this is done by thoracentesis or tube thoracostomy (chest tube); for ascites, with ascitic drain or paracentesis; and for pericardial effusion with pericardiocentesis. Absence of malignant cells on cytology does not completely exclude mesothelioma, this makes it much more unlikely, especially if an alternative diagnosis is possible (e.g. heart failure, tuberculosis). Unfortunately, the diagnosis of malignant mesothelioma by cytology alone can be difficult, even with professional pathologists.

However, a biopsy is needed to confirm a diagnosis of malignant mesothelioma. Your doctor removes a sample of tissue for examination under a microscope by a pathologist. A biopsy can be done in various ways, which depends on where the abnormal area is located. If the cancer is in the chest, your doctor can perform a thoracoscopy. What your doctor does is that he makes a small cut through your chest wall and puts a thin, lighted tube known as thoracoscope into your chest between the two ribs. What the thoracoscopy does is that, it allows your doctor to look inside your chest and obtain tissue samples. Alternatively, your chest surgeon might directly open your chest (thoracotomy). If the cancer is located in the abdomen, your doctor may perform a laparoscopy. To obtain tissue for examination, your doctor makes a small incision in your abdomen and inserts a special instrument into the abdominal cavity. Some times, if these procedures do not yield enough tissue, more extensive diagnostic surgery may be necessary.

However, immunohistochemical studies play an important part for the pathologist in differentiating neoplastic mimics from malignant mesothelioma. There are several tests and panels available. No single test is perfect for distinguishing carcinoma from mesothelioma or even benign versus malignant.