The symptoms of mesothelioma are often very similar to those of common illnesses like pneumonia, making mesothelioma difficult to diagnose. Determining the cause of symptoms will often require physicians to run a variety of tests after physical and oral exams.

To gather more information and visually identify potential tumors and fluid build-up, doctors will often order one or more types of imaging tests. These tests can include x-rays, CT scans, and PET scans to assist in determining the problem.

After imaging scans, a doctor may wish to test fluid or tissue to determine if the patient has mesothelioma or another form of cancer.  A biopsy is a common method to determine if the patient has mesothelioma.  If cytology (fluid) or pathology (tissue) is obtained, the cells can be stained by a pathologist to determine if the cells are cancerous (malignant) and if the cancer is mesothelioma.  The staining can also determine the cell-type which can be classified as epithelial, sarcomatoid, or mixed/biphasic.

Once diagnosed, these tests will also assist your physician in staging your mesothelioma.