The Definition and Diagnosisof of Mesothelioma

Definition

The most thorough definition of mesothelioma describes it as a rare cancer caused by asbestos fibers that have been lodged in the mesothelium for many years. The mesothelium is the membrane that encases organs such as the lung, the heart and those of the abdomen. Although it takes many years, these fibers can cause cancer cells to grow in the membrane tissue surrounding the fibers.

Mesothelioma most often develops in the membrane surrounding the lung, and results from inhaled asbestos fibers. This mesothelial membrane is called the pleura. Because lung tissue is so soft and porous, the motion of breathing massages the fibers through the lung tissue to the membrane. The consistency of the membrane is such that the fibers penetrate the pleura and remain trapped there.

Occasionally, fibers that are swallowed follow a similar path through the stomach wall where they become lodged in the lining around the stomach, called the peritoneum. With less frequency, fibers can pass through to the lining around the heart, called the pericardium. Mesothelioma can grow in any of these membranes.

Symptoms

Pleural mesothelioma symptoms can include thickening of the pleura, pleural effusion (fluid collecting in the pleural space), which in turn compresses the lung in that area reducing the amount of oxygen that can get into the blood. This causes shortness of breath along with some pain due to inflammation and, sometimes, infection. Persistent cough is common.

Symptoms of peritoneal mesothelioma might include stomach pain or swelling, bowel obstruction, foot swelling, nausea, weight loss, and pain.

Fever, night sweats, or anemia might also be symptoms of either form of mesothelioma. Diagnosis involves specific testing to differentiate it from other diseases, many of which have similar symptoms.

Diagnosis

There are a number of diagnostic tests that are used together with the results of a physical exam to make a diagnosis of mesothelioma. These tests differentiate between diseases and allow the doctor to rule out other diseases and cancers, identifying mesothelioma as the one that matches all of the diagnostic criteria.

These include:

X-rays
X-rays can reveal pleural effusion, pleural calcification, and scarring

CT or CAT Scan (Computed Axial Tomography)
CT Scans identify tissue density and can identify pleural effusion, pleural thickening and calcification, but it can't differentiate between mesothelioma and other disease.

MRI (Magnetic Resonance Imaging)
An MRI is more sensitive than CT or X-ray, and is useful for more accurate identification of tissue changes during the course of treatment, and evaluating for surgery.

PET Scan (Positron Emission Tomography)
PET Scans measure cellular activity. Cancer cells are more active than healthy cells, and this activity shows up in PET Scans.

Biopsy
A biopsy involves taking a sample of the suspect tissue, either with a needle or through a small incision, and sent to the lab for analysis.

PFT (Pulmonary Function Testing)
PFT involves a set of breathing tests to measure your lung volume, elasticity, airflow, and gas exchange into your bloodstream. These measurements reveal whether areas of your lung have a reduced volume or are not exchanging gas (i.e., from pleural effusion and resulting atelectasis, aka collapsed lung,) restrictive lung disease, or reduced airflow from obstructive lung disease.

CBC (Complete Blood Count)
CBC shows the number of red and white blood cells and platelets, the amount of hemoglobin, and the percent of blood that is red blood cells. It also tests other common blood factors that indicate health and illness.

Bronchoscopy
A bronchoscope is inserted into the patient's lungs through the throat that allows the doctor to view the trachea and upper airways. The scope has the ability to take a tissue sample that can be examined under a microscope, in the same was as tissue collected from a biopsy.

Cytology
A pathologist microscopically examines cells drawn from fluid near the site of the suspected disease.


The U.S. Department of Labor gives links to OSHA's standards and guidelines for evaluating exposure to asbestos. These links include medical questionnaires, X-ray interpretation standards, medical surveillance for asbestos and more.

Parker, Dumler & Kiely, LLP


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