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A diagnosis of mesothelioma is most often obtained with careful assessment of clinical and radiological findings in addition to a confirming tissue biopsy. (Learn about typical mesothelioma symptoms.) A review of the patient's medical history, including history of asbestos exposure is taken, followed by a complete physical examination, x-rays of the chest or abdomen, and lung function tests. A CT scan or MRI may also be done at this time. If any of these preliminary tests prove suspicious for mesothelioma; a biopsy is necessary to confirm this diagnosis.

There are several imaging techniques which may prove useful when mesothelioma is suspected due to the presence of pleural effusion combined with a history of occupational or secondary asbestos exposure. While these imaging techniques can be valuable in assessing the possibility of the cancer, definitive diagnosis is still most often established through fluid diagnosis or tissue biopsy.

Some of the most commonly used imaging methods include:

• X-ray

A chest x-ray can reveal pleural effusion (fluid build-up) which is confined to either the right (60%) or left (40%) lung. On occasion, a mass may be seen. Signs of prior non-cancerous asbestos disease, such as pleural plaques or pleural calcification, or scarring due to asbestosis may also be noted.

• Computed Tomography (CT)

CT scans are also able to define pleural effusion, as well as pleural thickening, pleural calcification, thickening of interlobular fissures, or possible chest wall invasion. CT, however, is not able to differentiate between changes associated with benign asbestos disease (pleural disease), or differentiate between adenocarcinoma of the lung wh

ich may have spread to the pleura verses mesothelioma. CT scans may also be valuable in guiding fine needle aspiration of pleural masses for tissue diagnosis.

• Magnetic Resonance Imaging (MRI)

MRI scans are most often used to determine the extent of tumor prior to aggressive treatment. Because they provide images in multiple planes, they are better able to identify tumors as opposed to normal structures. They are also more accurate than CT scans in assessing enlargement of the mediastinal lymph nodes (those lymph nodes which lie between the two lungs), as well as a clear diaphragmatic surface, both of which play an important role in surgical candidacy.

• Positron Emission Tomography (PET)

PET imaging is now becoming an important part of the diagnosis and evaluation of mesothelioma. While PET scans are more expensive than other types of imaging, and are not always covered under insurance, they are now considered to be the most diagnostic of tumor sites, as well as the most superior in determining the staging of mesothelioma. Further explanation of PET scans.

• CT/PET

For patients who may be candidates for aggressive multimodality treatment (surgery, chemotherapy and radiation), accurate clinical staging is extremely important. Integrated CT/PET imaging provides a relatively new tool in this respect, and has become the imaging technique of choice for determining surgical eligibility. By combining the benefits of CT and PET (anatomic and metabolic information) into a single scan, this technology can more accurately determine the stage of the cancer, and can help identify the best treatment option for the patient. Read about a study of CT-PET imaging in preoperative evaluation of patients with malignant pleural mesothelioma.

A needle biopsy of the mass, or the removal and examination of the fluid surrounding the lung, may be used for diagnosis, however, because these samples are sometimes inadequate as far as determining cell type (epithelial, sarcomatous, or mixed) or because of the unreliability of fluid diagnosis, open pleural biopsy may be recommended. In a pleural biopsy procedure, a surgeon will make a small incision through the chest wall and insert a thin, lighted tube called a thoracoscope into the chest between two ribs. He will then remove a sample of tissue to be reviewed under a microscope by a pathologist. In a peritoneal biopsy, the doctor makes a small incision in the abdomen and inserts a peritoneoscope into the abdominal cavity.

Once mesothelioma is suspected through imaging tests, it is confirmed by pathological examination. Tissue is removed, put under the microscope, and a pathologist makes a definitive diagnosis, and issues a pathology report. This is the end of a process that usually begins with symptoms that send most people to the doctor: a fluid build-up or pleural effusions, shortness of breath, pain in the chest, or pain or swelling in the abdomen. The doctor may order an x-ray or CT scan of the chest or abdomen. If further examination is warranted, the following tests may be done:

• Video-Assisted Thoracoscopic Surgery (VATS)

Over the past decade, the use of video-assisted thoracic surgery (VATS) has become one of the most widely used tools in the diagnosis of mesothelioma. Biopsies of the pleural lining, nodules, masses and pleural fluid can now easily be obtained using this minimally invasive procedure, and other therapies such as pleurodesis (talc) for pleural effusions can be done concurrently.While the patient is under general anesthesia, several small incisions or “ports” are made through the chest wall. The surgeon then inserts a small camera, via a scope, into one incision, and other surgical instruments used to retrieve tissue samples into the other incisions. By looking at a video screen showing the camera images, the surgeon is able to complete whatever procedures are necessary

In many cases, this video-assisted technique is able to replace thoracotomy, which requires a much larger incision to gain access to the chest cavity, and because it is minimally invasive, the patient most often has less post-operative pain and a potentially shorter recovery period.

• Thoracoscopy

For pleural mesothelioma the doctor may look inside the chest cavity with a special instrument called a thoracoscope. A cut will be made through the chest wall and the thoracoscope will be put into the chest between two ribs. This test is usually done in a hospital with a local anesthetic or painkiller.

If fluid has collected in your chest, your doctor may drain the fluid out of your body by putting a needle into your chest and use gentle suction to remove the fluid. This is called thoracentesis.

• Peritoneoscopy

For peritoneal mesothelioma the doctor may also look inside the abdomen with a special tool called a peritoneoscope. The peritoneoscope is put into an opening made in the abdomen. This test is usually done in the hospital under a local anesthetic.

If fluid has collected in your abdomen, your doctor may drain the fluid out of your body by putting a needle into your abdomen and using gentle suction to remove the fluid. This process is called paracentesis.

• Biopsy

If abnormal tissue is found, the doctor will need to cut out a small piece and have it looked at under a microscope. This is usually done during the thoracoscopy or peritoneoscopy, but can be done during surgery. More on needle biopsies.

Pathology, or the scientific study of cells, tissue, or fluid taken from the body is an integral part of a mesothelioma diagnosis. Most hospitals have their own pathology labs staffed by board-certified pathologists and licensed technologists. The importance of pathological diagnosis can not be underestimated, since the course of treatment is dependent upon an accurate diagnosis.

To make a diagnosis, pathologists examine tissue under a microscope, and based on established criteria, make a determination of benign vs. malignant cells. (More on biopsy tissue processing.) Subsequently, the type of cancer is determined. Although most pathologists have a general expertise of various diseases, a small number acquire training in a subspecialty, such as mesothelioma. These are physicians who have received world-wide recognition as premier experts, and have achieved high acclaim for their research, published articles and abstracts, and teaching. For a list of expert pathologists in the field of mesothelioma diagnosis, please call the MW toll free at 1-877-367-6376 or fill in the form at the bottom of this page specifying your request.

Knowing the stage is a factor in helping the doctor form a treatment plan. Mesothelioma is considered localized if the cancer is confined to the pleura, or advanced if it has spread beyond the pleura to other parts of the body such as the lungs, chest wall, abdominal cavity, or lymph nodes.

A diagnosis of any specific type of cancer often means ruling out other cancers in the process. This is true in the case of mesothelioma, where the most common “differential diagnosis” is that of adenocarcinoma versus mesothelioma.

During the biopsy procedure, the surgeon removes tissue samples to be sent to the laboratory. In the lab, slides are produced and then viewed and analyzed by a pathologist. These tissue specimens arrive at the lab with a request form that details patient information and history along with a description of the site in the body from which the specimen was obtained. Each individual specimen is numbered for each patient.

The pathologist then does a “gross examination” which consists of describing the tissue, and then placing it in a plastic cassette. The cassettes are then placed in a fixative that preserves the tissue permanently. Once the tissue has been fixed, it is processed into a paraffin block that will allow the pathologist to slice off thin microscopic sections that will then be stained to determine the patient’s diagnosis.

Immunohistochemistry is defined as “a method of analyzing and identifying cell types based on the binding of antibodies to specific components of the cell”. It is this process that helps diagnose mesothelioma versus adenocarcinoma (or other types of cancer).

Early on, the “markers” which helped distinguish mesothelioma from adenocarcinoma were “negative markers”; those expressed in adenocarcinomas, but not in mesotheliomas. This made it more difficult to confirm a diagnosis, because pathologists were dealing with the absence of, rather than the presence of certain markers. Some of these markers, which are normally “positive” in an adenocarcinoma diagnosis and “negative” in a mesothelioma diagnosis, are carcinoembryonic antigen (CEA), CD 15 (LeuM1), epithelial glycoprotein (Bg8), tumor glycoprotein (BerEp4) and tumor glycoprotein (MOC-31).

In more recent years, “positive markers” expressed by mesotheliomas have come to the forefront. Some of the markers which are normally “positive” in mesotheliomas and “negative” in adenocarcincomas are calretinin, cytokeratin 5, HBME-1, mesothelin, N-cadherin, thrombomodulin, vimentin and Wilm’s tumor gene product (WT-1).

It is important to remember that while the above markers are commonly used to help diagnose the epithelial sub-type of mesothelioma, that they may also be expressed in other types of cancer, and may not necessarily apply to the bi-phasic or sarcomatoid sub-types of mesothelioma. Your doctor can always contact a more specialized lab if he/she feels your diagnosis is in any way inconclusive.

The early symptoms of mesothelioma are generally non-specific, and may lead to a delay in diagnosis. Sometimes resembling viral pneumonia, pleural mesothelioma patients may present with shortness of breath, chest pain and/or persistent cough; some patients show no symptoms at all. A chest x-ray may show a build-up of fluid or pleural effusion (discussed below). The right lung is affected 60% of the time, with involvement of both lungs being seen in approximately 5% of patients at the time of diagnosis. Less common symptoms of pleural mesothelioma include fever, night sweats and weight loss. Symptoms of peritoneal mesothelioma may include pain or swelling in the abdomen due to a build-up of fluid, nausea, weight loss, bowel obstruction, anemia or swelling of the feet.

PLEASE KEEP IN MIND THAT THESE SYMPTOMS MAY BE CAUSED BY MESOTHELIOMA OR BY OTHER LESS SERIOUS CONDITIONS. ONLY A DOCTOR CAN MAKE A DEFINITIVE DIAGNOSIS.

Information on the symptoms, diagnosis, staging, and treatment of peritoneal mesothelioma.

Information on the symptoms, diagnosis, staging, and treatment of pleural mesothelioma.

One of the most common symptoms of mesothelioma is a pleural effusion, or an accumulation of fluid between the parietal pleura (the pleura covering the chest wall and diaphragm) and the visceral pleura (the pleura covering the lungs). Both of these membranes are covered with mesothelial cells which, under normal conditions, produce a small amount of fluid that acts as a lubricant between the chest wall and the lung. Any excess fluid is absorbed by blood and lymph vessels maintaining a balance. When too much fluid forms, the result is an effusion.

Pleural effusion is broken down into two categories, transudates and exudates. A transudate is a clear fluid that forms not because the pleural surfaces are diseased, but because of an imbalance between the normal production and removal of the fluid. The most common cause of transudative fluid is congestive heart failure. An exudate, which is often cloudy and contains many cells and proteins, results from disease of the pleura itself, and is common to mesothelioma. To determine whether a fluid is a transudate or exudate, a diagnostic thoracentesis, in which a needle or catheter is used to obtain a fluid sample, may be conducted.

As the volume of fluid increases, shortness of breath, known as "dyspnea", and sometimes pain, ranging from mild to stabbing, may occur. Some patients may experience a dry cough. When the doctor listens to the patient’s chest with a stethoscope, normal breath sounds are muted, and tapping on the chest will reveal dull rather than hollow sounds.

Diagnosis of pleural effusion is usually accomplished with a simple chest x-ray, although CT scans or ultrasound may also be used. A special x-ray technique, called a lateral decubitus film, may be used to detect smaller effusions or to enable the physician to estimate of the amount of fluid present. If the underlying cause of the effusion is readily apparent (such as in the case of severe congestive heart failure), sampling of the fluid may not be necessary, however, because pleural effusion may be symptomatic of a number of disease processes from benign to malignant, a fluid sample is generally taken. Diagnostic thoracentesis, in which cells are extracted from the pleural cavity, is commonly done when the possibility of mesothelioma exists, however, in up to 85% of cases, the fluid tests negative or inconclusive even though cancer is present. It is ultimately a needle biopsy of the pleura (lining of the lung) or an open surgical biopsy which confirms a mesothelioma diagnosis.

Pleural effusion caused by heart failure or infection can usually be resolved by directing treatment at the cause, however, when testing has realized no diagnosis, and fluid continues to build or recur, doctors may recommend chest tube drainage and chemical pleurodesis. Chemical pleurodesis is a technique in which a sclerosing agent is used to abrade the pleural surfaces producing an adhesion between the parietal and visceral pleurae. This will prevent further effusion by eliminating the pleural space. Talc appears to be the most effective agent for pleurodesis, with a success rate of nearly 95%. It is highly effective when administered by either poudrage or slurry. Poudrage is the most widely used method of instilling talc into the pleural space. Before spraying the talc, the medical team removes all pleural fluid to completely collapse the lung. After the talc is administered, they inspect the pleural cavity to be sure the talc has been evenly distributed over the pleural surface. Some doctors prefer to use talc mixed with saline solution which forms a wet slurry that can roll around the pleural cavity.

At some point in our lives, nearly all of us have been exposed to asbestos in the air we breathe and the water we drink; from natural deposits in the earth, and from the deterioration of asbestos products around us. Most of us, however, do not become ill as a result of our exposure. More commonly, those who at some point are diagnosed with asbestos disease, have worked in jobs where more substantial exposure occurred over longer periods of time. Nevertheless, cases of mesothelioma have been documented as the result of lesser exposure, affecting family members of workers who came into contact with asbestos and brought it home on their clothing, skin or hair, or affecting those who lived in close proximity to asbestos manufacturing facilities. Symptoms of asbestos disease usually are not be apparent until decades after exposure.

Asbestos was used commercially in North America as early as the late 1800s, but its use increased dramatically during the World War II era when shipyards produced massive numbers of ships for the war effort. Since that time, asbestos-containing products were used by the construction and building trades, the automotive industry and the manufacturing industry. All told, more than 5,000 products contained asbestos.

For more than 50 years, products containing asbestos remained unregulated, and the manufacturers of those products continued to prosper, knowing full well that many of the millions of workers who came into contact with their products would ultimately suffer as the result of their actions. Finally, in the late 1970s, the Consumer Products Safety Commission banned the use of asbestos in wallboard patching compounds and artificial ash for gas fireplaces because the fiber could easily be released during use. In 1989, the Environmental Protection Agency banned all new use of asbestos, but uses established prior to that time were still allowed. Although awareness of the dangers of asbestos and public concern over the issue have led to a decline in domestic consumption over the years, a total ban on asbestos has not come to fruition. Asbestos is still imported, still used and still dangerous.

Although it is suggested that the number of mesothelioma cases in the U.S. has reached its peak and has begun to drop, a forecast released by the National Cancer Institute's Surveillance, Epidemiology, and End Results Program (SEER), in April, 2003, projected the total number of American male mesothelioma cases from 2003-2054 to be approximately 71,000. This number, however, does not take into consideration events such as the World Trade Center disaster on September 11, 2001, when millions of New Yorkers were potentially exposed to air filled with carcinogenic asbestos particles. When the latency period for asbestos disease is factored in, cases of mesothelioma will continue to be diagnosed for years to come. See our page on mesothelioma risk factors.