Scans and x-rays can provide very strong evidence to support a diagnosis of mesothelioma especially when coupled with a history of exposure to asbestos. However a definite diagnosis of cancer can usually only be made by a pathologist (a doctor who specialises in assessing cells and tissue by looking at them through a microscope). He or she will be looking for characteristic changes in appearance that confirm that cancer is present. In the case of mesothelioma which is difficult to diagnose under the microscope it is often necessary to subject the tissue to a number of different very complex tests.
Where there is an accumulation of fluid as there can be in pleural mesothelioma (pleural effusion) and peritoneal mesothelioma (ascites) it is usual in the first instance for some of the fluid to be drawn off into a syringe and sent to the pathologist who will look for mesothelioma cells. This procedure is known as either a pleural aspiration or peritoneal aspiration. If the patient requires a drain to be inserted to allow an accumulation of fluid to be removed slowly over a few days, a sample of the fluid will usually be taken from the drain and sent for analysis.
It is usually necessary for a sample of tissue from the thickened pleura or peritoneum to be taken in order to identify mesothelioma cells. The removal of a piece of tissue for diagnostic purposes is called a biopsy. Part of a lump, a large section or a thin core of tissue may be removed using a variety of methods.
Sometimes the biopsy is done at the same time that the drain is inserted and whilst the patient is undergoing a scan. The scanning equipment will guide the doctor with greater certainty to an affected part of the pleura or peritoneum.
Mesothelioma is a very difficult disease to diagnose, and as well as the scans and procedures described above, it may be necessary for the patient to undergo a small (key hole) exploratory operation, under a general anaesthetic. This will also enable the doctors to fully understand the extent of the disease. If not already done, a biopsy may also be performed during the operation.
Whatever type of biopsy you have it can take several days for the analysis to be performed and in some cases longer as the specimen may be sent to a pathologist in another part of the UK.
All of the above procedures involve some discomfort and risk. Where possible it is best for a diagnosis of Mesothelioma to be confirmed by a pathologist. There are times however, when a patient is not well enough to undergo, or chooses not to proceed further, with the tests to confirm a diagnosis. Sometimes, despite having all of the above biopsy procedures, the doctors are unable to confirm the diagnosis.