Key Takeaways
- Diagnosing malignant pleural mesothelioma (MPM) is a multi-step process that typically begins with symptom evaluation and occupational history, followed by imaging tests and ultimately a biopsy to confirm the diagnosis.
- Initial symptoms — persistent cough, chest pain, fatigue, and difficulty breathing — overlap with many other conditions, making asbestos exposure history a critical early diagnostic clue.
- Imaging progresses from chest X-ray (which can reveal calcium buildup, fluid, or pleural thickening) to CT scan (which provides clearer cross-sectional views of soft tissue and organs).
- Blood tests for biomarkers — elevated biological substances associated with mesothelioma — can support the diagnosis before a biopsy is performed.
- A biopsy (tissue sample from the affected area) is the most reliable way to confirm MPM and distinguish it from lung cancer, pneumonia, or other conditions.
- Diagnosis can be complicated by tumor heterogeneity — the same tumor may show different cell types depending on where the biopsy is taken, leading to potential misdiagnosis.
- A deep learning algorithm called MesoNet has been developed to identify different heterogeneous MPM cell presentations, opening the door to AI-assisted diagnostics that could improve accuracy and speed of diagnosis in the future.
Traditional Diagnostic Measures For Diagnosing Malignant Pleural Mesothelioma
- The patient usually presents with symptoms local to the chest and/or lungs. These
symptoms can include a persistent cough, general pain in the chest area, fatigue, and
difficulty breathing. - To rule out other diagnoses, providers will first gather a patient’s medical and
occupational history. If the patient has suffered occupational exposure to asbestos, then
the following processes of imaging and histological samples might be expedited. - An X-Ray of the chest might be ordered. This will visualize possible calcium build-ups
on the pleural tissues, whether there might be an excess of fluid between the lungs and
the spaces outside/between them, or a thickening of the pleural tissues. - Next, a CT (computed tomography) will likely be conducted. These scans use radiation,
much like X-Rays, but can visualize soft tissues and organs much clearer through
cross-sectional “slices” of the body. - Next, a doctor might order blood tests, as patients with mesothelioma often have elevated
levels of certain biological substances. These are called biomarkers. - Lastly, to ensure the correct diagnosis of MPM (rather than lung cancer, pneumonia, a
different cancer altogether, etc.), doctors will often take a biopsy, which is a small sample
of living tissue extracted from the affected area. Scientists will then take this sample and
compare it to previous mesothelioma manifestations; this is an excellent clinical strategy
that is largely successful for diagnosis.
Exceptions to Traditional Diagnostic Methods
While most patients with mesothelioma are diagnosed in the sequence of the aforementioned,
some patients escape proper diagnosis: “…a significant rate of MPM show a wide spectrum of
clinical manifestations, unusual radiologic and morphologic appearances, aberrant or “null”
phenotype at immunohistochemistry, or even combinations of all these features [9],” (Rossi, et.
al).
Even when biopsies are performed, MPM often presents as heterogeneous, meaning that
depending on the location within the tumor that the biopsy is performed, there are different
genetic and phenotypic (physical) presentations of cells. This presents a significant barrier to
correct diagnosis.
Recently, an algorithm (MesoNet) was trained to identify the different heterogeneous
manifestations of MPM cells: “This deep learning algorithm highlighted the great heterogeneity
of various parts of MPM. Based on this artificial intelligence approach, expert thoracic
pathologists proposed another morphologic subtype of MPM more recently, namely transitional
histology, in the attempt to identify a subgroup of MPM with dismal prognosis and challenging
morphology between epithelioid and sarcomatoid feature [116],” (Rossi et. al). This has exciting
implications for future MPM diagnostic techniques: as supplemented with AI, doctors will
hopefully be able to accurately diagnose MPM in less time. This might also contribute to an
increased prognosis–if MPM is detected earlier and with more accuracy, then it can be addressed
much sooner.
If you or a loved one has been diagnosed with an asbestos-related disease, please call
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Frequently Asked Questions
How is malignant pleural mesothelioma diagnosed?
Diagnosis typically follows a step-by-step process:
- Symptom evaluation — the patient presents with persistent cough, chest pain, fatigue, or difficulty breathing
- Medical and occupational history — doctors assess whether the patient has a history of asbestos exposure, which can expedite further testing
- Chest X-ray — can reveal calcium buildup on pleural tissues, fluid between the lungs and surrounding spaces, or thickening of the pleural lining
- CT scan — provides detailed cross-sectional images of soft tissues and organs for a clearer view than X-ray alone
- Blood tests (biomarkers) — mesothelioma patients often have elevated levels of certain biological substances that support the diagnosis
- Biopsy — a small tissue sample is extracted from the affected area and compared to known mesothelioma cell patterns to confirm the diagnosis
Why is a biopsy necessary to confirm mesothelioma?
Mesothelioma symptoms and imaging findings overlap significantly with other conditions — including lung cancer, pneumonia, and other cancers. A biopsy provides a tissue sample that can be examined at the cellular level, allowing pathologists to compare the cells to known mesothelioma presentations and rule out other diagnoses. Without a biopsy, there is a meaningful risk of misdiagnosis, which can lead to incorrect or delayed treatment.
Why is mesothelioma difficult to diagnose?
Several factors make mesothelioma challenging to diagnose:
- Symptom overlap — cough, chest pain, and breathing difficulty are common across many respiratory conditions
- Long latency period — symptoms may not appear until 20 to 50 years after asbestos exposure, and patients may not connect their illness to past exposure
- Tumor heterogeneity — the same tumor can present different cell types depending on where the biopsy sample is taken, potentially misleading pathologists
- Atypical presentations — some mesothelioma cases show unusual radiological, morphological, or immunohistochemical features that don’t match standard diagnostic patterns
These factors are why a thorough diagnostic workup — including occupational history, multiple imaging modalities, and biopsy — is essential.
What is tumor heterogeneity and why does it matter?
Tumor heterogeneity means that different areas within the same tumor may contain cells with different genetic and physical characteristics. In mesothelioma, this means a biopsy taken from one part of a tumor might show epithelioid cells, while a sample from another area might show sarcomatoid features. This can lead to an incomplete or inaccurate subtype classification, which directly affects treatment decisions and prognosis — since epithelioid mesothelioma generally responds better to treatment than sarcomatoid.
What is MesoNet and how could AI improve mesothelioma diagnosis?
MesoNet is a deep learning algorithm that was trained to identify the different heterogeneous cell presentations within mesothelioma tumors. By analyzing biopsy samples at a level of detail beyond what the human eye can consistently detect, MesoNet helped expert pathologists identify a new morphologic subtype called transitional histology — a subgroup with features between epithelioid and sarcomatoid types and a particularly challenging prognosis. AI-assisted diagnostics like MesoNet could lead to faster, more accurate diagnoses and potentially improve outcomes by enabling earlier, more targeted treatment.
What are biomarkers and how are they used in mesothelioma diagnosis?
Biomarkers are measurable biological substances in the blood that can indicate the presence of a disease. Mesothelioma patients often show elevated levels of specific biomarkers, which can support a diagnosis before a biopsy is performed. The most well-known is mesothelin, which is currently the only FDA-approved biomarker for mesothelioma. While biomarkers alone cannot confirm a diagnosis, they provide valuable supporting evidence alongside imaging and tissue analysis.
Why does occupational history matter for diagnosis?
Because mesothelioma is almost exclusively caused by asbestos exposure, a patient’s occupational history is one of the most important early diagnostic clues. If a patient presenting with chest symptoms has a history of working in an asbestos-heavy industry — shipyards, steel mills, construction, insulation, auto repair, power plants — doctors may expedite imaging and biopsy testing rather than pursuing other diagnoses first. Without knowing the exposure history, mesothelioma can be misdiagnosed as lung cancer, pneumonia, or another respiratory condition, delaying critical treatment.
What should I do if I have a history of asbestos exposure and am experiencing symptoms?
If you or a loved one has a history of asbestos exposure and is experiencing persistent cough, chest pain, shortness of breath, or unexplained fatigue, tell your doctor about your exposure history immediately — this can significantly speed up the diagnostic process. Early detection expands treatment options and may improve outcomes. For information about your legal options, call (800) 505-6000 or fill out our contact form.
