Diagnosing Mesothelioma: Medical Tests and Imaging
Mesothelioma is a rare cancer that forms in the thin layer of tissue covering the lungs, chest wall, abdomen, or heart. Because its early symptoms — shortness of breath, chest pain, a persistent cough, or unexplained weight loss — closely resemble common conditions like pneumonia or bronchitis, the disease is often suspected only after other treatments fail to help. Reaching a reliable diagnosis typically requires a combination of imaging scans, fluid analysis, and tissue sampling.
Starting With a Detailed Medical History
The diagnostic process usually begins with a physical exam and a thorough review of your health history. Your doctor will ask about any past exposure to asbestos, which is the primary cause of mesothelioma. In Missouri, that question matters. Asbestos was used for decades in construction, insulation, automotive parts, and industrial equipment across the state, including in manufacturing plants in St. Louis and Kansas City, power stations along the Missouri and Mississippi rivers, and older schools, hospitals, and commercial buildings. People who worked in those settings, or who lived with someone who did, may have been exposed without knowing it.
Imaging Tests
Imaging studies help doctors see abnormalities in the chest or abdomen and guide the next steps.
- Chest X-ray: Often the first test ordered. It can reveal pleural thickening, fluid buildup, or masses, but it cannot confirm mesothelioma on its own.
- CT scan (computed tomography): Provides detailed cross-section images of the chest and abdomen. A CT scan is the most common imaging tool used to evaluate the extent of disease and to guide biopsy procedures.
- PET scan (positron emission tomography): Uses a small amount of radioactive sugar to highlight areas of high metabolic activity, which can help distinguish cancerous tissue from scar tissue and identify whether the disease has spread.
- MRI (magnetic resonance imaging): Produces highly detailed images of soft tissue. It is sometimes used to check whether the cancer has invaded the chest wall, diaphragm, or other nearby structures.
Fluid Analysis and Biopsy
Imaging alone cannot confirm a mesothelioma diagnosis. A biopsy — the removal of a small tissue sample for examination under a microscope — is required.
If fluid has collected around the lungs (a pleural effusion), a doctor may first perform a thoracentesis, inserting a thin needle to drain the fluid. The fluid can be tested for cancer cells, though this test alone is not always conclusive.
For a more definitive diagnosis, a tissue biopsy is needed. Common methods include:
- Needle biopsy: A long, thin needle is guided by CT or ultrasound into the suspicious area to remove a small sample.
- Thoracoscopy: A surgeon makes small incisions and inserts a camera and instruments to view the pleural space and take tissue samples directly. This method often provides the most reliable results.
- Laparoscopy or mediastinoscopy: Similar techniques used to sample tissue in the abdomen or around the chest cavity.
Once the tissue is collected, a pathologist examines it under a microscope. Specialized tests, including immunohistochemistry, help distinguish mesothelioma from other cancers that can look similar, such as lung adenocarcinoma. These tests look for specific proteins on the surface of the cells, which helps confirm the diagnosis and identify the cell type.
Staging and Next Steps
If mesothelioma is confirmed, additional imaging and testing help determine the stage of the disease — how far it has spread. Staging guides treatment decisions and helps your care team develop a plan tailored to your situation. In Missouri, patients may receive care at major cancer centers in St. Louis, Kansas City, Columbia, and Springfield, where multidisciplinary teams of pulmonologists, thoracic surgeons, oncologists, and pathologists work together throughout the diagnostic process.
Reaching a correct diagnosis can take time, and it is normal to feel anxious during the process. Ask your doctor to explain each test, what it is looking for, and what the results may mean. A clear understanding of your diagnosis is the first step toward making informed decisions about your care.
This page is for general informational purposes only and is not legal or medical advice. Reading it does not create an attorney-client relationship. Consult a licensed attorney or physician about your specific situation.
