Pleural Mesothelioma: Diagnosis

Pleural mesothelioma is a type of malignant mesothelioma, along with peritoneal mesothelioma, pericardial mesothelioma and testicular mesothelioma. Pleural mesothelioma is a rare form of cancer. Malignant mesothelioma is caused almost exclusively by exposure to asbestos. The symptoms often resemble other ailments. As a result, diagnosis can be tricky. Symptoms appear only in the late stages of the disease. There are no symptoms of pleural mesothelioma in the early stages. Symptoms appear only after the lung linings are covered in cancerous tumors and fluid builds up in the sac surrounding the lungs, called the pleura.

Early detection sometimes happens when the patient has another complaint that makes multiple X-Rays or CT scans necessary and the doctor notices a change in the shape of the lungs over time as a result, or detects small, localized tumors before the cancer spreads. Under those circumstances, the prognosis may be good. Localized tumors can be removed with surgery, leaving enough healthy lung tissue to allow the patient a much longer lifespan. Early diagnosis is extremely rare, however, and pleural mesothelioma is hard to identify even by an experienced doctor.

Most people are familiar with screening procedures for other conditions, diseases and cancers. Women are taught to self-exam for breast cancer, for example, and have a mammogram performed every year or two after age 45. During a self-exam, tumors can be felt, and a mammogram shows tumor masses. Other conditions, like diabetes or thyroid disease, have blood tests that show abnormalities that indicate problems. Pleural mesothelioma has no such screening or test that alarms the doctor to the condition, and the disease goes undetected while it spreads to deadly proportion.

Testing for Pleural Mesothelioma

Diagnosis usually results when a patient visits the doctor to have symptoms checked out. He may be experiencing shortness of breath, pain in the chest or back, painful, persistent coughing or any number of other symptoms, none of which immediately alert the doctor to a diagnosis of pleural mesothelioma. The symptoms mimic familiar ailments like influenza, pneumonia, and other common upper respiratory illnesses. The doctor will listen to the lungs and may decide that the patient has pneumonia, an infection that causes fluid in the lungs. The sensible thing to do at this point is to prescribe a strong antibiotic and rest, and send the patient home. Pneumonia patients are rarely hospitalized at first, because fighting pneumonia suppresses the immune system and makes patients vulnerable to other infections.

When the antibiotics do not improve the patient’s condition, the real detective work begins. The doctor may order an X-ray or CT scan, perform a blood test, take an in-depth history from the patient, and he may biopsy the lungs and send a sample to the lab to be analyzed. If cancer is suspected after all this, or the doctor cannot determine the cause, he will refer the patient to the hospital or to a cancer specialist, called an oncologist. The oncologist will perform additional tests and ask more questions.

X-Rays and CT Scans

Most people, at some point during their lives, receive an X-ray, a scan that shows what is going on inside the body. An X-ray ordered by the oncologist may show fluid and/or masses, or tumors in the lungs. A CT scan is another way to image the inside of the body, and may indicate abnormal swelling and the presence of masses. A dye is administered prior to the test to help pinpoint abnormalities.

Fluid Drainage

Fluid buildup around the lungs, called pleural effusion, is the most common symptom of pleural mesothelioma. This fluid squeezes the lungs, making expansion difficult and breathing labored and painful.

The oncologist drains the fluid using a long needle attached to a tube connected to a collection bag. The needle is inserted into the pleura to drain the fluid into the bag. This serves to relieve the pressure on the lungs and to provide a sample for analysis. Fluid containing cancer cells helps verify a pleural mesothelioma diagnosis.

Thoracoscopy

Biopsy is the most reliable way to arrive at a pleural mesothelioma diagnosis. To perform a biopsy, a local or general anaesthetic is administered to numb the area. A surgeon then makes a small incision to insert a thoracoscope. A thorascope is a thin, flexible tubing attached to a light and a video camera. The images produced by the camera help the surgeon find the affected area. Using forceps, the surgeon snips a small sample of the cancerous pleura tissue for testing.

The Results

On television, doctors hand deliver tissues to the lab and pace anxiously while the technicians drop everything and perform the tests that lead to immediate diagnosis. In real life, the lab is rarely in the same building and test results can take two to four weeks. It can be a difficult and frightening wait for patients, but the doctor has no control over when the test results will be returned. Once the diagnosis of pleural mesothelioma is confirmed, the oncologist calls the patient and often his spouse or family members in for a meeting to deliver the prognosis and discuss treatment options for this type of malignant mesothelioma, caused almost exclusively by the exposure to asbestos.

Your doctor may perform some of the following procedures to diagnose pleural mesothelioma.

CT scan

This type of X-ray provides a very detailed picture of the size and location of the cancer. The images taken are compiled by a computer to create a more complete image of the disease. The procedure is also called a computerized axial tomography (CAT) scan.

PET scan

A procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body.

Thoracoscopy

The diagnosis of malignant pleural mesothelioma may involve your doctor looking inside the chest cavity with an instrument called a thoracoscope. For this procedure, an incision is made through the chest wall and the thoracoscope is put into the chest between two ribs. This procedure is usually done in the hospital.

Bronchoscopy

A bronchoscopy involves an examination of the lungs and air passages. The doctor places a lighted tube down the patient’s throat and trachea into the lungs. This procedure is called a bronchoscopy, and the instrument used is called a bronchoscope.

Thoracentesis

Some patients develop fluid in their lungs. This is called a pleural effusion. Your doctor might take a sample of this fluid with a needle injected into the chest and test the fluid for cancer cells. Your doctor may also perform this procedure for draining fluid from the lungs to help relieve pain.

Mediastinoscopy

This is a test that examines the mediastinum. This area is in the center of your chest, between your lungs, and contains the heart, blood vessels and lymph nodes.

Needle Biopsy

For this procedure, the doctor uses a thin needle to take samples of cells for examination under microscope. This test can be uncomfortable but may take only a few minutes. Small pieces of the tissue are taken and then sent to a laboratory for analysis.

The doctor might also use an X-ray, CT scan or fluoroscopy to guide the needle as it is inserted into the tumor. Fluoroscopy is a diagnostic procedure in which X-rays are passed through the body and then projected onto a screen, providing a continuous image of the body’s internal structures.

Wedge Biopsy

For this procedure, a doctor makes an incision through the skin, and a wedge of tissue or tumor is obtained and sent to a laboratory for analysis. A wedge biopsy is often used when other biopsy methods have been unable to confirm a diagnosis.

Cytology and Pathology

Pathology is a study of a disease, which looks at specific cells and types of a disease process to determine the cause. Pathology tests are performed on samples of body fluid or tissue to determine the cell type (cytology) of a specific disease. The process of looking at these samples may include using microscopes, electron microscopes and various stains. This refers to special cell-staining techniques that identify specific types of malignant mesothelioma tumors. Certain types of dyes or coloring are added to the patient’s biopsy samples. Depending on how the tissue responds to the dye, the doctor can make a better estimate about the outcome of the illness. In making the diagnosis, the more information the doctor has about the tumor, the better he or she can recommend appropriate treatment.

After your biopsy, a sample of the tissue or fluid removed may be sent to a hospital laboratory to be analyzed.

• If fluid is removed during a thorancentesis or thorascopy, it is sent to a Cytology lab for analysis. Your doctor will receive a written report of the results. The doctor may receive an oral report from the lab prior to the written results.

• If a tissue biopsy from a bronchoscopy, needle biopsy or thorascopy is done, it is sent to a surgical pathology lab for analysis. The final report will be sent to your doctor.

• Surgical removal of a tumor, pleura or lung is sent to a surgical pathology lab. In the lab the material is analyzed with special stains. The material may be placed under a microscope for magnification and further review to determine the cell type. After analysis is completed, small pieces of any remaining tissue are preserved in paraffin for future us