How is mesothelioma diagnosed?

Like other asbestos-related diseases, a mesothelioma diagnosis often starts with an x-ray or CT scan. However, the disease begins as tiny lumps or nodules in the lining of the lungs or other organs, which are not always picked up on an x-ray or scan until they grow in size. For this reason, mesothelioma can, at least initially, be difficult to diagnose. Often a number of tests are required to diagnose the cancer and it is common for the disease to be misinterpreted for other forms of disease.

Diagnosis of pleural mesothelioma

Because the cancerous mesothelioma cells can irritate the pleura, or lining of the lung, sometimes a pocket of fluid will develop. This is known as a pleural effusion and because mesothelioma is sometimes present in this fluid, a sample can be taken to help diagnose mesothelioma. This is known as cytology.

Mesothelioma biopsy

Providing the sufferer is well enough, they may be able to undergo a biopsy procedure to assist in diagnosing pleural mesothelioma. This requires a sample to be taken from the pleura or the lymph nodes. The biopsy may be conducted in a variety of ways, including via:

  • Thoracoscopy

A thoracoscopy is a form of biopsy that will allow a medical professional to look directly at the pleura and other structures which form part of the lungs. The thoracoscopy will be guided to the thicker areas of the pleura, allowing the doctor to take a biopsy of the “at risk” area.

  • CT or ultrasound-guided biopsy

Following a local anaesthetic, a medical professional can pass a special needle through the skin which is then guided using ultrasound or a CT scanner to the area of the lungs where mesothelioma may have developed. Once the needle has reached the area it can dissect a sample of the tissue for testing purposes.


If a doctor believes the mesothelioma may have spread to the lymph nodes, then a mediastinoscopy may be required. Often conducted under general anaesthetic, this procedure will allow doctors to look at the lymph nodes which are located in the space in between the lungs. This will allow biopsies to be taken if they are required.

Diagnosis of peritoneal mesothelioma


As with pleural mesothelioma, x-rays or CT scans are often the first step taken by medical experts in diagnosing peritoneal mesothelioma. Ultrasounds may also be used to scan the abdomen. This allows doctors to view the blood flow and check for any abnormal growths. Ultrasounds are painless and safe, as there is no radiation involved resulting in little by way of side effects.

Laparoscopy and biopsy

In order to take a biopsy, under a local anaesthetic a small cut is made in the abdomen and a laproscope is inserted through the cut. This is a tube with a camera and light. This allows the doctor to see inside the abdomen and look for signs of mesothelioma. If any abnormal looking areas are found, biopsies are taken. The small cut is then stitched up and the biopsies sent for testing.