Overview of Pleural Mesothelioma Diagnosis

How Doctors Diagnose Pleural Mesothelioma

Pleural mesothelioma diagnosis consists of a series of exams, tests, and procedures to determine the nature of tissue masses discovered in the pleura, the lining of the lungs. Because so many symptoms are shared between this form of cancer and other conditions, doctors must pay special attention to the history of the patient to discover markers that point to pleural mesothelioma. Asbestos inhalation or consumption is the most common factor among diagnosis of pleural mesothelioma, so physicians must explore the patient’s history including occupation and other mesothelioma risk factors.

While mesothelioma is the third most deadly form of cancer, the number of deaths following diagnosis of pleural mesothelioma account for only a very small percentage of all deaths from conditions that carry the same symptoms. Diagnosing pleural mesothelioma often occurs many years after the onset of symptoms, after a series of other possible conditions have been eliminated. Pleural mesothelioma is often confused with conditions such as adenocarcinoma, a lung cancer with almost identical symptoms.

As discussed in further detail below, a diagnosis of pleural mesothelioma is concluded when most or all of the variables of mesothelioma and cancer have been satisfied.

•  A physical examination by a physician confirms symptoms and may discover superficial lumps on the chest region.
•  Blood tests confirm a high concentration of substances known to accompany mesotheliomas.
•  Imaging scans detect abnormal tissue in the chest cavity or on the lungs, specifically within the pleura.
•  Biopsy results prove malignant cancer exists in the pleura.
•  Specialists use imaging and biopsy results to determine origin and growth of malignant pleural mesothelioma. (Typing, Staging, Prognosis)

Tests Employed During Pleural Mesothelioma Diagnosis

After an initial consultation during which a doctor performs a physical examination to look for superficial abnormalities and considers any history of exposure to asbestos, the patient is directed to a specialist in order to begin a series of imaging scans that must be done in the hospital and interpreted by a radiologist.

Chest X-Rays and Computed Tomography (CT) Scans

When attempting to diagnose pleural mesothelioma, a chest x-ray is the tool most often utilized to initially check for the abnormal masses or tumors within the chest cavity and pleura. X-ray technology is normally employed when the patient has a consistent cough or breathlessness. In addition to providing an inside peek into the condition of the lungs; a chest x-ray is useful in diagnosis of pleural mesothelioma by making it possible to see the following signs of cancer.

•  Presence of pleural thickening or an abnormally thick pleura
•  Tissue masses and tumors that may be cancerous
•  Calcium Deposits
•  Fluid in the chest between the lungs and outer chest wall
•  Asbestos related lung damage

A CT scan also uses x-rays to assist in a pleural mesothelioma diagnosis. Unlike a chest x-ray, CT scans employ a technique that takes multiple pictures of the chest from various angles. A computer then combines the photos to create complete, cross-sectional images of the chest cavity.

CT scans provide more diagnostic information than a standard chest x-ray, including:

•  A cross sectional view of chest cavity, including soft tissue composition
•  Exact location and depth of cancer
•  Stage of pleural mesothelioma.

Positron Emission Tomography (PET) Scans

PET scans work by taking pictures of cancerous cells that react to a radioactive substance. During diagnosis of pleural mesothelioma, a slightly radioactive glucose known as FDG is injected into the bloodstream.

A PET scanner then takes a photo of radioactivity in the body. Since they grow faster and therefore absorbed more glucose, cancer cells “light up” brighter than normal cells and are easy to identify on resulting the image.

Magnetic Resonance Imaging (MRI) Scan

An MRI uses radio waves and strong magnetic fields to provide soft tissue information, similar to that provided by a CT scan. Some patients are injected with a contrast fluid to improve the image detail. A computer is used to translate patterns created y the radio waves and magnets to create a detailed image of the chest cavity.

MRI scans are most useful in diagnosing an abdominal variety of mesothelioma, but can provide more detailed images for diagnosis of pleural mesothelioma where the cancer cells have spread into muscles and other soft tissue.

Biopsy’s Role in Pleural Mesothelioma Diagnosis

While physicians will employ a series of imaging tests to determine the location and stage of the cancer, diagnosing pleural mesothelioma requires careful examination of the cells found in abnormal tissues detected by imaging scans. Biopsies provide an accurate diagnostic analysis of those cells and are critical in diagnosing pleural mesothelioma.

During a biopsy, a sample of the abnormal tissue is removed from the body and examined closely under a microscope. The process of removing the tissue depends on the location of the tissue to be examined. To accurately diagnose pleural mesothelioma, the biopsy procedure must allow doctors to gain access to the affected area.

While there are many procedures that enable doctors to extract cells from the chest cavity, some are more effective than others. Needle biopsies are less likely to provide an accurate diagnosis of pleural mesothelioma simply because it only collects a small amount of cells from a small area.

Once the tissue has been removed it is examined by a specialist known as a histologist; a doctor that specializes in cytology, the study of cells. The histologist looks closely for the markers of epithelioid and sarcomatoid cancer cells, the definitive indicators that abnormal tissue is cancerous (malignant).

Some obvious cases of pleural mesothelioma are biphasic, which means that both types of cancer cells are present (epithelioids and sarcomatoids). It can take much less time to conclude a diagnosis of pleural mesothelioma if histologists are able to detect both cell types in a single pleural tumor, though malignant pleural mesothelioma is deadly when just one or the other is present.

The prognosis after a diagnosis for pleural mesothelioma is often dismal because the cancer remains undetected for many years, allowing time for it to grow beyond some treatments. As pleural mesothelioma worsens, the treatment options become more limited and life expectancy falls at a proportionate rate. The average life expectancy following the diagnosis of pleural mesothelioma is less than one year if there is no positive response to treatment.