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What is mesothelioma?

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What is mesothelioma?

For many people, and their families, a diagnosis of mesothelioma is an unwelcome introduction to a disease they may never have heard of and they will want to find out everything they can about the disease. We address a number of our clients' most common questions here but, for more information we would recommend visiting Mesothelioma UK website who we are proud to support as members of their legal panel.

Mesothelioma is a type of cancer that affects the membrane that lines certain internal organs.  This membrane is called the mesothelium and is a thin layer of tissue that can be found in the lining of the lungs (the pleura), the lining around the abdominal cavity (the peritoneum) and the lining around the heart (the pericardium).

Exposure to asbestos is thought to be responsible for over 90% of mesothelioma cases.  It has been suggested that there may be other rare causes of mesothelioma but they are probably not fully understood at the moment.  It is well established that mesothelioma is not caused by smoking tobacco.

Asbestos is a fibrous mineral.  When the tiny asbestos fibres become airborne then they can be inhaled and ingested.  The fibres may remain dormant in the body for many years.  It is thought that it usually takes between 30—40 years from when asbestos exposure took place for any symptoms to come to light although it can take more or less than 30-40 years in some cases.  Asbestos fibres can cause genetic mutations to cells in the body that leads to the growth of cancer.  

Mesothelioma is associated with occupational asbestos exposure and traditionally affects people who have worked in heavy industries such as shipbuilding, power stations and the construction industry.  These are examples of cases that we have dealt with over the years from people from a diverse range of occupations and backgrounds. 

However, mesothelioma can also be caused by very low levels of asbestos. 

There have been reported cases of people contracting mesothelioma from contact with family members who worked with asbestos, through washing clothes contaminated with asbestos and by children playing around asbestos factories and areas where asbestos waste was dumped.

The two main types of mesothelioma are pleural mesothelioma and peritoneal mesothelioma.  Rarely, mesothelioma can arise in other areas such as the pericardium (the lining around the heart) and the testicles.

Pleural mesothelioma

Pleural mesothelioma is the more common type of the disease.  The pleura is a lining of the chest wall that consists of two layers called the visceral (inner) layer and the parietal (outer) layer. The space between the two layers is called the pleural space and contains a small amount of fluid that lubricates the two layers and allows them to slide comfortably over each other when we breathe in and out.  A tumour can grow on the pleura which will form a solid coating around the lung and may cause breathing to become restricted and painful.

Peritoneal mesothelioma

Peritoneal mesothelioma is less common than pleural mesothelioma.  The peritoneum is the lining of the abdomen which again consists of two layers and helps to protect organs.  It produces fluid which helps the abdominal organs to move smoothly against each other as we move around.

Peritoneal mesothelioma causes the peritoneum to thicken and stop working properly.  Because pleural mesothelioma is more common than peritoneal mesothelioma and can spread to the abdomen, it may be necessary to clarify whether or not pleural mesothelioma is the primary cancer.

Different cell types of mesothelioma

As well as mesothelioma being found in different parts of the body, there are different cell types of mesothelioma.  These can be identified by looking at the cancerous cells under a microscope.

There are three different cell types of mesothelioma: epithelioid mesothelioma, sarcomatoid mesothelioma and biphasic mesothelioma.

Epithelioid mesothelioma is the most common type and tends to grow more slowly than the others, so may respond better to treatments.  When viewed under a microscope the cells appear relatively uniform and are cube shaped.

Sacrcomatoid is less common than epithelioid mesothelioma and can be more aggressive.  The cells are less uniform and oval in appearance.

Biphasic mesothelioma is a mixture of the two other types and contains both types of cells.

The symptoms of mesothelioma will take many years to show up after asbestos exposure first took place.  In the early stages of the illness the symptoms can be vague and similar to the symptoms of a cold or flu such as coughing, chest pain and shortness of breath.

Mesothelioma predominantly occurs in the pleura (the lining of the lungs).  In relation to pleural mesothelioma, often the first major sign that something may be wrong is when fluid builds up in the pleural space.  This is known as a pleural effusion and the build up of fluid can restrict the ability of the lung to expand as you breathe and can cause breathlessness and chest pain.  A pleural effusion may be found after a chest x-ray has been carried out. 

A surgical procedure known as pleural drainage or aspiration may be carried out to drain away the fluid which will make it easier to breathe and may relieve chest pain.  This often provides very rapid relief but sometimes the relief is only short-lived as the effusion can recur.

As the tumour progresses further symptoms may develop.  These may include:
  • A persistent cough or wheezing
  • A hoarse voice
  • Tiredness and fatigue
  • Loss of appetite and weight loss
  • Difficulty in swallowing food
  • Nausea and vomiting
  • Bloody sputum
  • Unexplained fever and sweating
  • Recurring chest infections
  • Abdominal pain.  This may be particularly associated with peritoneal (stomach) mesothelioma.
If you have any of the above symptoms then you should see your doctor straight away and they can arrange for tests to be carried out.

In the latter stages of the illness symptoms may progress, so it is important to seek medical advice to make sure that treatments are made available.  Various treatments may be offered to help to treat and palliate the symptoms and make sure that the sufferer is kept as comfortable and free of pain as possible.

Initial stages

It is not always easy to diagnose mesothelioma as some of the initial symptoms can be quite vague and general, such as tiredness, weight loss, shortness of breath and chest pain.  

Visiting a GP

When you visit your GP they will carry out an examination and take a history. Your GP may tap your chest and use a stethoscope.  They will be looking for any signs of fluid collecting on the lungs and reduced chest expansion.

Your GP might refer you to a hospital for a chest x-ray or sometimes, directly to a specialist lung doctor (a respiratory physician).

Seeing specialist doctors at the hospital

Your specialist may have received preliminary information from your GP as well as x-ray and scan results, if they have already been carried out.  They will typically examine you, ask about your medical history and symptoms and may ask about previous occupations and whether you might have been exposed to asbestos.  Other tests may be arranged such as routine blood tests and breathing tests to measure how your lungs function.


You will almost always be asked to have a chest or abdominal x-ray at an early stage to look for abnormalities.  An abdominal x-ray may show if there is any fluid or swelling in the abdomen, and a chest x-ray can show if there is fluid known as a pleural effusion in the lungs.  There are various causes of pleural effusion so the presence of fluid does not mean that a diagnosis of mesothelioma will follow.  A diagnosis of mesothelioma can often only be confirmed after further tests have been carried out.

CT scans

A CT scan is a computerised scan using x-rays that takes detailed pictures of a cross section of the inside of the body.  CT stands for computed tomography.  It shows a lot more detail than a normal x-ray, and may be carried out on the chest or abdomen. You may be given an injection of a dye called a contrast before the scan is performed.  This makes the scan easier to read.  The hospital will provide information about the CT scan such as how long it will take, how long you should avoid eating and drinking for before the scan, etc.

The CT scan pictures will be looked at by a doctor called a radiologist who specialises in reporting on x-rays and scans.  The radiologist will write a report and send this to the specialist doctor who originally asked for the scan to be carried out.  Sometimes a CT scan will be used when a biopsy is carried out.

Ultrasound scan

This is a scan of internal organs and/or blood vessels using a probe that produces high frequency sound waves.  A warm gel will be applied to the skin and a probe used to take images which can be seen on a television screen.  An ultrasound of the abdomen will usually be needed to show up fluid in the tummy.  The results will be interpreted by a radiologist or sonographer who will send the information to the consultant who asked for the scan.

MRI scan

An MRI (magnetic resonance imaging) scan is similar to a CT scan.  A contrast agent (a colourless liquid that can be seen on the scan) may be used.  The scan involves using a powerful magnet to produce very detailed images on a computer.  Again, the results will be sent by the radiologist to the specialist doctor who requested the scan.

PET scan

A PET (positron emission tomography) scan uses a very small amount of a low dose radioactive contrast agent to show up areas of the cancer. PET scans are relatively new and the patient may have to travel to a specialist centre for the scan to be performed.  They may be combined with a CT scan to make them more accurate.

Pathology tests

X-rays and scans (known as radiology) provide very important evidence to try to reach a correct diagnosis.  However, what is known as pathological evidence will usually be necessary to establish a firm diagnosis.  Pathology means tests which involve a specialist doctor (a pathologist) analysing fluid and tissue samples by looking at them with a microscope and using special chemicals.  These tests are known as staining and will usually be carried out to establish a diagnosis of mesothelioma.   

Pleural or peritoneal fluid

Fluid can build up in the pleura (pleural effusion) or peritoneum (ascites) due to inflammation.  This can cause breathlessness and in cases of peritoneal mesothelioma can make the abdomen feel swollen and uncomfortable.  A procedure called pleural or peritoneal aspiration can be preformed to provide relief and enable a pathologist to analyse the fluid to look for cancer cells.  The fluid may be drawn off using a syringe and a drain may be fitted to allow the fluid that accumulates to be removed slowly through a tube.

Analysis of the fluid (known as cytology) may not always lead to the detection of mesothelioma cells and typically in the majority of cases, a biopsy will be carried out.


A biopsy is the removal of a piece of tissue in order to reach a diagnosis.  It is usually necessary for a sample of tissue to be taken from the pleura or peritoneum to enable a pathologist to identify mesothelioma cells and lead to a diagnosis of mesothelioma.  There are different ways that samples can be taken.  The amount of tissue that is removed varies and might be removed as part of a thin core of tissue, a large section or a lump.

A biopsy with a scan/fluid drainage

A biopsy can be carried out while you are undergoing a scan, or when drainage is being performed.  The scanning equipment may help to better identify the areas of the pleura or peritoneum that are affected.

However, mesothelioma can be a difficult illness to diagnose.  It may be difficult for the pathologist to decide if the cells or tissue are a type of mesothelioma or not.  The cells can look similar to other types of cancer such as lung cancer in the case of pleural mesothelioma.  Therefore, it is often necessary for you to undergo a surgical biopsy.   

Thoracoscopy/video assisted thoracoscopic surgery (VATS)

A thoracoscopy is a small operation carried out under either local or general anaesthetic by a specialist when a flexible tube with a video and light attached (a thoracoscope) is passed through a small cut (usually about 1-2 cm) in the chest wall.  

An ultrasound or CT scan may be used to position the needle correctly. The doctor will then take a sample from the pleura.  This procedure may require a short stay in hospital for the patient.


A laparoscopy will be carried out to try to diagnose peritoneal mesothelioma.  It involves a small operation whereby a doctor puts a tube with a camera and light into your abdomen through a small cut.  It might be carried out under local or general anaesthetic and the doctor will look for any sign of cancer and take biopsies.  Sometimes more than one surgical cut will be necessary.

The results

The biopsy samples will be sent off to a laboratory for tests to be carried out.  Sometimes the samples will be sent to a specialist pathologist in another hospital for a second opinion.  It may take a few weeks sometimes before the results are available, particularly if the samples have to be sent off to another hospital for a second opinion. This will obviously be a very anxious time.  The doctor will ask you to come back to the hospital when the results are available and will discuss the findings, the diagnosis and possible treatments.

To assist in reaching a diagnosis hospitals have teams of experts called multi-disciplinary teams (MDT’s).  They consist of specialist health professionals with different areas of expertise who regularly meet to discuss whether they believe the diagnosis is correct, the stage of the disease and possible treatments.

Staging mesothelioma

If mesothelioma has been diagnosed then it will be helpful to find out what stage the illness is at.  This is known as staging and will describe the size and position of the tumour and whether it has spread to lymph nodes or other parts of the body.  Working out the stage is helpful because it will assist the doctors in making decisions about possible treatment, although it may not be easy for the stage to be calculated precisely.

The system that is used in the UK for pleural mesothelioma is the International Mesothelioma Interest Group (IMIG) staging system with stage 4 being the most advanced stage and stage 1 the least advanced.


This will depend on a number of factors including your general fitness, any pre-existing health conditions, the type of mesothelioma and the stage your illness is at.

It is not the intention of this website to offer a comprehensive guide about available treatment options and this is something that should be discussed with your treating doctors.  More information is available from the charity Mesothelioma UK, who we work closely with

This can vary based on your individual circumstances. Pleural effusions (build-up of fluid in the lung) are commonly drained to alleviate symptoms and doctors will attempt a procedure to insert surgical talc to try to prevent the build up of fluid.

It is common for those with mesothelioma to be treated with palliative chemotherapy in an effort to stabilise the disease.  Radiotherapy and surgery may also be considered.

Some types of treatments may be offered as part of a clinical trial.  The results of trials can help to improve treatment in the future, but their availability varies considerably.  The most up to date information can be found on the Mesothelioma UK clinical trials page.

How can Leigh Day help fund treatment in the private sector?
As a result of research some “second line” treatments that have seen promising results in trials are available privately in the UK. 

Immunotherapy is an emerging form of treatment for mesothelioma. Immunotherapy trials are ongoing and may be available.  Alternatively, immunotherapy treatment can be provided in the private sector, although it be can extremely expensive.   

Leigh Day are experts in bringing successful claims when compensation for the cost of immunotherapy has been recovered from defendants as part of successful claims.

If you’ve been exposed to asbestos, suffered from a related disease and believe you have a strong claim, contact the team of asbestos lawyers at Leigh Day. 

They’ll listen to your case with a free consultation and assess the strength of your claim, advising you on the best next steps to take. 
You can also make asbestos claims after death for someone else when you are appointed as a ‘litigation friend’. 
To strengthen any asbestos, asbestosis or mesothelioma claims, you may need to gather supporting evidence for your case. This can include medical records, documents, witness statements, work and financial records. 
Call the team on freephone 0808 2315982
In an industrial disease case, you can bring a legal claim within a three-year ‘limitation period’. This typically starts from the date of diagnosis, but it may be earlier if you have already identified a connection between your symptoms and the cause.  

For asbestos claims after death, the three year period typically runs from the date of death. 

In all circumstances, it’s advisable to seek legal advice as soon as possible. Sometimes it’s possible to ask the court to let your claim proceed despite the fact that it is over three years since you were diagnosed. Leigh Day has experience bringing cases ‘out of time’.

Mesothelioma UK

Leigh Day is proud to be a member of the Mesothelioma UK legal panel