Diagnosing Mesothelioma

When a mesothelioma sufferer first goes to the doctor with symptoms of the disease, the most common complaints are:

Chest pain
Difficulty breathing
Shortness of breath
Persistent dry cough

These symptoms are the result of the mesothelioma tumor causing fluid build-up between the two layers of the membrane surrounding the lungs, heart, or abdominal organs. These membranes are known as the pleural mesothelium, peritoneal mesothelium, or pericaridal mesothelium respectively.

Pleural Mesothelioma

In pleural mesothelioma, this fluid build-up is called pleural effusion. To determine what’s causing the plueral effusion, the doctor has several tests and procedures available.

Chest X-ray

With a chest X-ray, the doctor can easily see the fluid build-up and determine the symptoms are the result of “water on the lungs” as it’s sometimes called. But pleural effusion can be caused by many diseases, almost all of which are far more likely to occur than mesothelioma.

Pneumonia
Lung infections
Tuberculosis
Congestive heart failure
Kidney disease
Bowel disease
Pericarditis
Liver disease
Pancreas disease
Rheumatoid arthritis
Lupus
Lung tumor
Blood clot in the lung

Depending on how advanced the disease is, the X-ray may also show signs of plaque, calcification or scarring that can be indicative of asbestosis – an asbestos-caused disease that frequently occurs in advance of mesothelioma. Additionally, the X-ray may reveal a mass that could indicate a possible tumor.

Thoracentesis

To narrow down the potential causes, the doctor must take a sample of the fluid. The procedure, a thoracentesis, involves using a local anesthetic and inserting a needle through the skin into the pleural space to withdraw a small amount of fluid. Examination of the fluid classifies it as transudate or exudate.

Transudate is a clear fluid and can signal congestive heart failure or kidney, bowel, or liver disease, or an inflammation of the membrane surrounding the heart (pericarditis).
Exudate is a cloudy fluid indicating an infection, tumor, blood clot in the lung, or any of the other remaining diseases on the list.

Knowing the possibilities, the doctor can explore the patient’s signs and symptoms more closely to determine which are the more likely possibilities and order the appropriate follow-up tests.

Scans

If the signs begin pointing toward some type of tumor or other visible disease process, the doctor will use a more detailed imaging method such as a CT scan, MRI, or PET scan to gather additional information for diagnosis.

CT Scan. Computerized tomography (CT) can provide further evidence of mesothelioma, but it may not be definitive. From a CT scan alone, the doctor may not be able to effectively distinguish mesothelioma from asbestos pleural disease or a lung cancer tumor that has spread to the lung lining.

MRI. Magnetic resonance imaging (MRI) provides more detailed images of internal structures, allowing the doctor to more clearly see any tumors and their locations, as well as assess other internal conditions that may determine whether surgical treatment is feasible.

PET Scan. Rather than showing structures within the body, positron emission tomography (PET) reveals biological functioning. Using slightly radioactive substances that are absorbed during biological processes, the PET scan can show the location, or degree, or efficiency of these processes. Rather than for diagnosis, PET is used more in determining the stage of the mesothelioma tumor for deciding on treatment options.

Thoracoscopy

As the evidence mounts of a tumor on the mesothelium, the doctor must ultimately collect a tissue sample from the tumor to make a definitive diagnosis. Knowing the location of the suspect mass from earlier scans, the doctor uses a thoracoscope to look inside the chest through a small incision while the patient is under a local or a general anesthetic. After pinpointing and examining the mass, the doctor takes a small biopsy for laboratory examination.

Pathology

The pathologist examining the tissue sample must first distinguish the tumor cells to determine what kind of cancer cells they are. When mesothelioma is determined, the cells can be examined further to determine if the cancer is sarcomatous, epithelial, or biphasic.

If the doctor took tissue samples from more than one location, the presence or absence of cancer cells in different locations can help determine to what degree the cancer may have spread. This information can be useful in determining the cancer stage, which is important in determining an appropriate treatment strategy.

Peritoneal and Pericardial Mesothelioma

When mesothelioma attacks the membrane surrounding the abdominal organs rather than the lungs, the disease is referred to as peritoneal mesothelioma. Though pleural mesothelioma is most common, peritoneal mesothelioma occurs in about 25% of cases. If the doctor needs to drain excess fluid collecting between the two layers of the peritoneum, the procedure is called peritoneocentesis. The procedure for the internal examination is peritoneoscopy and the device used is a peritoneoscope.

Mesothelioma of the membrane surrounding the heart (pericardial mesothelioma) only occurs in 5% to 10% of cases, but diagnosis is similar.