A tumor of the tissue that lines the lungs, stomach, heart, and other organs

Malignant mesothelioma is a type of cancer that occurs in the thin layer of tissue that covers certain internal organs of the body. This is an aggressive and deadly form of cancer. Treatments are available, but for many people there is no cure.

Malignant mesotheliomas can start in four main parts of the body:

  • Pleural mesotheliomas start in the chest and are most common.
  • Peritoneal mesotheliomas start in the lining of the abdomen.
  • Pericardial mesotheliomas start in the lining of the heart cavity.
  • Mesotheliomas of the tunica vaginalis start in the covering of the testicles.

Malignant mesotheliomas are also classified by type, depending on how the cancer cells are arranged:

  • About half of mesotheliomas are epithelioid. This type tends to have a better outlook than the other types.
  • About 10 percent of mesotheliomas are sarcomatoid. This is the most difficult to treat.
  • The remaining are mixed - they have both epithelioid and sarcomatoid areas.


In most cases, treatments may help reduce symptoms and improve survival odds but will not cure the cancer. Most patients are treated with chemotherapy.

Malignant mesothelioma is usually diagnosed at an advanced stage when it isn’t possible to remove the cancer through surgery. In some cases when patients are diagnosed at an early stage, they can be treated with surgery and radiation.

Symptoms and Diagnosis

Malignant mesothelioma is a type of cancer that occurs in the thin layer of tissue that covers certain internal organs of the body.


It can take 20 to 50 years for symptoms of mesothelioma to develop after first exposure to asbestos. Symptoms of malignant mesothelioma vary depending on where the cancer occurs.

Signs of pleural mesothelioma, which affects the tissue in the chest and lungs:

  • Chest pain under rib cage
  • Painful coughing
  • Shortness of breath
  • Weight loss
  • Unusual lumps under chest

Signs of peritoneal mesothelioma, which affects the abdomen: 

  • Abdominal swelling
  • Abdominal pain
  • Lumps in abdomen
  • Weight loss

Signs of pericardial mesothelioma, which affect the heart:

  • Breathing difficulty
  • Chest pain

Symptoms of tunica vaginalis, which affects the testicles:

  • Swelling or mass on a testicle


Because mesothelioma is so rare, your doctor will first test to see if another more common disease is causing your symptoms. As part of your medical history, your doctor will ask if you have ever been exposed to asbestos. 

The following are also used to help diagnose mesothelioma:

  • Imaging, such as X-rays to look for fluid in the lungs or CT scan to look for tumors. MRI and PET scans can help diagnose metastasis (spreading) of the mesothelioma.
  • Blood tests to look for substances in the blood that can indicate mesothelioma cancer cells.
  • Biopsy, which tests a sample of your affected tissue, to positively confirm a mesothelioma diagnosis.

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