Pleural Mesothelioma

Two layers of tissue make up the lining around the lungs, known as the pleura. These tissues protect and support the lungs and other important structures of the chest. They also produce lubricating fluid between the two to help the lungs move smoothly as we breathe. The outer layer, the parietal pleura, lines the entire inside of the chest cavity. The inner layer, or visceral pleura, covers the lungs. 

Mesothelioma commonly affects both layers of the pleura. The cancer generally forms in one layer and rapidly invades the other pleural layer, diaphragm, chest wall or lung. If the cancer reaches nearby glands called lymph nodes, it can metastasize, or spread, to other parts of the body. Pleural mesothelioma can be difficult to diagnose, since symptoms usually do not arise until long after the first exposure to asbestos. Since many diseases of the lungs and respiratory system have the same symptoms as pleural mesothelioma, doctors may mistake it for the flu or pneumonia.

Reliable Ways to Diagnose

Diagnosing pleural mesothelioma can involve a multi-step process because early symptoms often mimic other conditions.

Medical History and Physical Exam

The doctor will discuss your symptoms and past medical history, including any potential asbestos exposure. A physical exam will assess for signs like chest pain or difficulty breathing.

Imaging Tests

Imaging techniques help visualize abnormalities in the chest cavity. These may include:

• Chest X-ray: An initial screening tool to detect abnormalities like pleural effusion (fluid buildup) or pleural thickening.
• CT Scan: Provides detailed cross-sectional images to pinpoint location and size of potential tumors.
• PET Scan: Might be used to assess if cancer has spread to other parts of the body.

Biopsies

A definitive diagnosis usually requires a biopsy, where a tissue sample is collected for microscopic examination. Biopsy options include:

• Thoracentesis: Doctors insert a hollow needle into the lungs to collect pleural fluid. Cell samples from the fluid are examined under a microscope to look for substances that indicate the presence of cancer. A thoracoscopic biopsy produces an accurate diagnosis in 98% of mesothelioma patients.
• Surgical biopsy: In some cases, a more involved surgical procedure might be needed to obtain tissue.

If a series of tests or biopsies confirm the presence of mesothelioma, doctors develop a treatment plan based on the results. Similar diagnostic tests will be performed on different parts of the body for other forms of mesothelioma.

For example, even though similar imaging scans and biopsies are used to diagnose all types of mesothelioma, the part of the body that undergoes imaging or biopsy will differ for each type of mesothelioma. Because mesothelioma locally invades the body cavity in which it develops before spreading, doctors rarely have a hard time differentiating one form of mesothelioma from another. Only in late stage IV cases may there be enough spreading to or from the lung to the abdomen to question whether the cancer originated in the lining of the lungs or abdomen.

Fluid Analysis

If pleural effusion is present, the fluid may be withdrawn and analyzed for the presence of abnormal cells.

Blood Tests

Blood tests are not a primary diagnostic tool but might be used to check for general health or specific markers sometimes elevated in mesothelioma.

Why Is It Difficult to Confirm a Pleural Mesothelioma Diagnosis?

While doctors may suspect mesothelioma based on a patient’s symptoms, history of asbestos exposure and irregular imaging scan results, these signs are not enough to confirm a diagnosis.

It is challenging for doctors to diagnose pleural mesothelioma for several reasons: 

• Non-specific symptoms: Early signs of pleural mesothelioma, like chest pain and shortness of breath, are often vague and can mimic other, more common conditions. This can lead to delays in diagnosis as other possibilities are explored first.
• Long latency period: It can take decades for mesothelioma to develop after initial asbestos exposure. This means symptoms might not appear until years after the window of highest risk has passed, making it harder to link the current condition to past exposure.
• Similar appearance to other cancers: Under a microscope, mesothelioma cells can sometimes closely resemble cells from other cancers, particularly lung cancer. This necessitates specialized testing and analysis to ensure an accurate diagnosis.
• Difficulty obtaining tissue samples: Early-stage tumors might be very small or located in hard-to-reach areas of the chest cavity. Obtaining sufficient tissue for a conclusive biopsy can be challenging in some cases.

The Importance of Early Diagnosis

Early detection offers a better chance of successful treatment and improved prognosis. Here are several reasons an early diagnosis is critical for pleural mesothelioma:

• Improved treatment options: Early-stage mesothelioma is generally confined to the pleura, allowing for more aggressive treatment approaches. This might include surgical resection (removal) of the tumor, which can potentially offer a cure in some cases. Later stages, where the cancer has spread, often rely on palliative care focused on managing symptoms and improving quality of life.
• Increased effectiveness of treatment: Early intervention with surgery, radiation, or chemotherapy has a higher chance of success when the cancer is less extensive. These treatments can be more effective at shrinking tumors and controlling the disease when it's caught earlier.
• Enhanced prognosis: Studies have shown a clear link between earlier diagnosis and a better prognosis for pleural mesothelioma. Early detection offers a greater chance of achieving longer remission and improved survival rates.
• Better quality of life: Early diagnosis and treatment can potentially help patients maintain a higher quality of life for longer. Treatment side effects might be more manageable when the cancer is less advanced.

If you have concerning symptoms or a history of asbestos exposure, discussing it with your doctor is crucial for prompt diagnosis and timely intervention.