Your doctor will review your work history, especially whether you have worked in an industry in which you may have been exposed to asbestos.

The diagnosis of malignant mesothelioma begins with a thorough medical history to document the patient's symptoms and any possible asbestos exposure, followed by a complete physical examination. These steps generally are followed by a chest or abdominal X-ray, computed tomography (CT) or magnetic resonance imaging (MRI) scan. The imaging studies allow the physician to assess the size, location and extent of the tumor in the chest or abdomen.

If fluid is present in the pleura or peritoneum, a thin needle may be used to collect a small sample of the fluid for examination. This procedure, called fine-needle aspiration, also may be used to drain the fluid to relieve symptoms such as chest pain and shortness of breath that can result from an effusion. Occasionally, mesothelioma can be diagnosed with this fluid sample alone, but usually a tissue sample (biopsy) is required. The tissue sample can be obtained via thoracoscopy (for a pleural tumor) or via laparoscopy (for an abdominal tumor). In both procedures, a tubelike instrument inserted through a small incision allows the physician to view the tumor and collect a tissue sample. Patients suspected of having pleural mesothelioma also may need a procedure called bronchoscopy.