Quite often the diagnosis may not be clear after these initial tests and a larger sample is needed.  This may be done using a thoracoscope, where a small flexible telescope is inserted into the chest, allowing the chest wall to be carefully inspected.  This procedure is performed under a full general anaesthetic.

The diagnosis of mesothelioma is made by a specialist pathologist.  The samples require complex processing and considerable skill in interpreting.  It may take two weeks or more for all the tests to be completed to ensure a completely accurate diagnosis.

Sadly, at this time mesothelioma is almost invariably fatal with a median survival of 4 to 18 months following diagnosis. Despite its rising importance as a cause of lung cancer mortality there is a deficit in evidence-based therapeutic options for mesothelioma. The majority of patients have dyspnoea (up to 80%) and a large unilateral pleural effusion at the time of presentation [3,4].  There is currently no consensus as to which method to control such pleural effusion is preferable. In many centres the most rapidly, and logistically feasible, approach is medical talc pleurodesis. This is not always successful and surgery is sometimes still necessary to control the pleural effusion.

Mesothelioma Diagnosis

Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions.  Diagnosis begins with a review of the patient’s medical history, including any history of asbestos exposure. A complete physicale xamination may be performed, including x-rays of the chest or abdomen and lung function tests. A CT (or CAT) scan or an MRI may also be useful. A CT scan is a series of detailed pictures of areas inside the body created by a computer linked to an x-ray machine. In an MRI, a powerful magnet linked to a computer is used to make detailed pictures of areas inside the body. These pictures are viewed on a monitor and can also be printed.A biopsy is needed to confirm a diagnosis of mesothelioma. In a biopsy, a surgeon or a medical oncologist (a doctor who specializes in diagnosing and treating cancer) removes a sample of tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside thechest and obtain tissue samples. If the cancer is in the abdomen, the doctor may perform a peritoneoscopy. To obtain tissue for examination, the doctor makes a small opening in the abdomen and inserts a special instrument called a peritoneoscope into the abdominal cavity. If these procedures do not yield enough tissue, more extensive diagnostic surgery may be necessary.  If the diagnosis is mesothelioma, the doctor will want to learn the stage (or extent) of the disease. Staging involves more tests in a careful attempt to find out whether the cancer has spread and, if so, to which parts of the body. Knowing the stage of the disease helps the doctor plan treatment.  Mesothelioma is described as localized if the cancer is found only on the membrane surface where it originated. It is classified as advanced if it has spread beyond the original membrane surface to other parts of the body, such as the lymph nodes, lungs, chest wall, or abdominal organs.

Descriptions: 

Physical Examination
An exam of the body to check for general signs of disease.

X-ray 
A type of high-energy radiation. In low doses, x-rays are used to diagnose diseases by making pictures of theinside of the body. In high doses, x-rays are used to treat cancer.

MRI
Magnetic resonance imaging (mag-NET-ik REZ-o-nans IM-a-jing). A procedure in which radio waves and apowerful magnet linked to a computer are used to create detailed pictures of areas inside the body. Thesepictures can show the difference between normal and diseased tissue. MRI makes better images of organs andsoft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain,spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging (NMRI).

CT scan
Computed tomography scan. A series of detailed pictures of areas inside the body taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called computerized tomography and computerized axial tomography (CAT) scan.Biopsy.  The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under amicroscope or perform other tests on the cells or tissue. When only a sample of tissue is removed, the procedure is called an incisional biopsy. When an entire lump or suspicious area is removed, the procedure is called an excisional biopsy. When a sample of tissue or fluid is removed with a needle, the procedure is called a needle biopsy, core biopsy, or fine-needle aspiration.

Surgeon
A doctor who removes or repairs a part of the body by operating on the patient.

Oncologist
A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancertreatment. For example, a radiation oncologist specializes in treating cancer with radiation.PathologistA doctor who identifies diseases by studying cells and tissues under a microscope.Chest WallThe muscles, bones, and joints that make up the area of the body between the neck and the abdomen.

Surgery
A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.StageThe extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodescontain cancer, and whether the cancer has spread from the original site to other parts of the body.StagingPerforming exams and tests to learn the extent of the cancer within the body, especially whether the diseasehas spread from the original site to other parts of the body. It is important to know the stage of the disease inorder to plan the best treatment.

Mesothelioma Diagnosis Information -
LocalizedRestricted to the site of origin, without evidence of spread.

Lymph node
A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filterlymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphaticvessels. Also called a lymph gland.Source: http://www.cancer.gov