Mesothelioma Diagnosis

How Is Mesothelioma Diagnosed?

Mesothelioma diagnosis may involve a combination of tests, including a physical exam, imaging tests, fluid analysis and biopsies to confirm this rare cancer. If you’ve been exposed to asbestos and are experiencing symptoms such as chest pain or trouble breathing, your doctor may recommend one or more of the following tests.

Tests Used to Diagnose Mesothelioma

• Medical history and physical exam
• Imaging scans, including X-ray, CT, MRI and PET
• Blood tests
• Fluid analysis
• Biopsy, which confirms the diagnosis

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Your doctor may refer you to an oncologist for further tests for mesothelioma. Your oncologist will listen for sounds in your chest or abdomen that may indicate fluid buildup, a common sign of mesothelioma. Then, you’ll likely have imaging tests to identify where tumors are located and how far they’ve spread, a process known as staging the disease. However, the diagnostic process is not the same for everyone, and the order of tests may vary.

Pleural mesothelioma survivor Linda Hooper told us that she had an ultrasound, blood tests, CT scans and MRIs before a biopsy revealed that she had cancer. “All of the tests that I’d had done up until this point said no cancer, no cancer, no cancer. That was from the MRIs and everything. So at least what I knew when I went in for that biopsy is what I didn’t have. And then when I woke up from the surgery, the surgeon was like, ‘You have cancer. It’s mesothelioma.'”

Medical History and Physical Exam

Doctors start by reviewing your medical history, especially any history of asbestos exposure. They also look for physical signs such as fluid buildup in the chest or abdomen, which may indicate pleural or peritoneal mesothelioma. 

Then, your doctor will do a physical exam, checking for symptoms of mesothelioma, such as fluid buildup in the chest or abdomen, which may indicate pleural or peritoneal mesothelioma. They’ll also check for fluid around the heart, which may be a sign of pericardial mesothelioma. In rare cases of testicular mesothelioma, they perform a physical examination of the groin area.

Imaging Tests for Mesothelioma

Mesothelioma imaging tests, including PET scans, X-rays, echocardiograms, CT scans and MRIs, help doctors locate and assess mesothelioma tumors. Some scans involve contrast dye. Most scans are generally quick and painless. MRIs can take 30 to 90 minutes.

Types of Mesothelioma Imaging Scans

• Computed tomography (CT) scans: CT scans produce high-resolution cross-sections with detailed views of tumor size and location.
• Echocardiograms: A noninvasive procedure, echocardiograms use ultrasound to create an outline of the movement of the heart. These are used for pericardial mesothelioma.
• Magnetic resonance imaging (MRI) scans: MRIs use a strong magnetic field and radio waves to form detailed images of the person’s soft tissues.
• Positron emission tomography (PET) scans: PET scans use an injected radioactive tracer to find cancer cells. PET/CT scans combine both as a more comprehensive tool.
• X-rays: These are most likely the first imaging test done. X-rays can identify pleural or peritoneal tumors. X-rays only provide a 2D view.

Doctors use imaging scans to see signs of asbestos exposure. They look for hardened areas on the lung lining called pleural plaques. These signs and other tests help doctors see if an asbestos-related disease is present.

Some scans such as MRIs may cause anxiety in some patients. Health care providers may prescribe anti-anxiety medications. These drugs help patients relax during the scan.

Blood Tests

There is no blood test that can diagnose mesothelioma on its own, but some blood tests look for certain proteins or other biomarkers that can indicate mesothelioma. Some mesothelioma biomarkers can also show up in people who don’t have this cancer. This is why doctors need other tests like biopsies and scans to confirm mesothelioma. Examples of blood tests used to diagnose mesothelioma include MESOMARK, N-ERC/mesothelin and fibulin-3 blood tests. Blood tests are also used to detect genetic mutations like BAP1, which may affect treatment outcomes.

Fluid Analysis (Cytology Tests)

Mesothelioma cytology tests help doctors find cancer cells in fluid. Doctors collect samples from effusions or ascites from the chest, abdomen or heart area. Then, they use a microscope to search for cancer cells. If they find cancer cells, it helps them diagnose mesothelioma.

Types of Mesothelioma Cytology Tests

• Paracentesis: Doctors insert a needle into your belly to remove fluids for testing. This test is common for people with peritoneal mesothelioma.
• Pericardiocentesis: A needle is inserted into your chest to remove fluid from around your heart. This test is common for those with pericardial mesothelioma.
• Thoracentesis: Doctors insert a needle into your chest. This procedure is common for people with pleural mesothelioma.

Cytology tests and biopsies help diagnose mesothelioma, according to a 2024 study published in the Journal of the American Society of Cytopathology. The key difference between the two tests is cytology tests examine fluid, while biopsies take tissue samples. Biopsies give more information about cancer cells, which is how doctors determine whether you have cancer.

Biopsies

A biopsy is the only way to confirm a mesothelioma diagnosis. This medical procedure involves taking a sample of tissue and studying it under a microscope to check for cancer cells. Doctors suggest a biopsy if you show signs of mesothelioma. Imaging scans, such as CT or PET scans, help guide where the sample should be taken from and assess cancer spread.

Types of Mesothelioma Biopsies

• Laparoscopy: Doctors make a small cut in the abdomen and use a tiny camera and tools to take a tissue sample. This type of endoscopic biopsy is best for peritoneal mesothelioma.
• Mediastinoscopy: A small cut is made above your breastbone, then doctors use a tube with a light to see and take tissue. This is for biopsies of the lymph nodes and around the windpipe for pleural mesothelioma.
• Needle biopsy: A thin needle is put through your skin to take a small piece of tissue. Also known as a fine-needle aspiration, it’s used for tissue samples that are hard to collect. 
• Surgical biopsy: A larger cut is made to remove a tissue sample when other methods don’t work. This is used when an endoscopic or fine-needle biopsy isn’t possible. 
• Thoracoscopy: Doctors make a small cut in the chest, then use a tube with a camera to look and take tissue. This is the most accurate biopsy for diagnosing pleural mesothelioma.

Thoracic surgeon and pleural mesothelioma specialist Dr. Jeffrey Velotta told us, “It’s really important that patients see a mesothelioma specialist, or at least get referred to one for a potential biopsy for mesothelioma, because specialists including myself, we know what to look for, and we know how much tissue to get.”

Staging Mesothelioma Cancer

Staging helps doctors determine how far mesothelioma tumors have spread and plan the best treatment for patients. The 4 stages of mesothelioma range from early stage (stages 1 and 2) to late stage (stages 3 and 4). The higher the number, the more the cancer has spread from where it started.

• Stage 1: Localized tumors may have the best treatment outcomes.
• Stage 2: Some tumors may have spread to nearby tissues or lymph nodes.
• Stage 3: Tumors have spread farther, but surgery may still be possible.
• Stage 4: Cancer has spread extensively, and palliative care is best.

An early-stage diagnosis improves treatment options. A late-stage diagnosis makes these treatments less effective. Later stages become more difficult to treat.

In 2025, The Mesothelioma Center at Asbestos.com conducted a survey where we asked more than 200 survivors, caregivers and their loved ones about their cancer stage at the time of diagnosis.

The TNM staging system is the official system doctors use to stage pleural mesothelioma. It identifies tumor size, location and whether cancer cells have entered lymph nodes or metastasized. Doctors use a modified TNM system for peritoneal mesothelioma. There is no official staging system for pericardial or testicular types.

“When staging mesothelioma, I assess where the cancer is located, how far it has spread and which organs are involved,” said Dr. Andrea Wolf, a thoracic surgeon and director of the New York Mesothelioma Program at Mount Sinai. “This information is essential in developing the most effective treatment plan for each of my patients.”

How Long Does It Take to Receive a Mesothelioma Diagnosis?

A mesothelioma diagnosis can take several weeks or even months. This is often because early symptoms, such as fatigue or shortness of breath, resemble more common illnesses. Many people go through multiple tests and see more than one doctor before receiving an accurate diagnosis.

The timeline depends on how quickly a specialist gets involved and whether a biopsy is performed early. For some, the process feels confusing or delayed, especially without guidance from a doctor familiar with mesothelioma.

Understanding what to expect can help you feel more prepared and in control. The checklist below can help you keep track of your next steps and know when it’s time to ask for support.

Are You Prepared for a Mesothelioma Diagnosis?

Use this checklist to track what you’ve gathered and what questions to ask next.

• I’ve written down my symptoms and asbestos exposure history.
• I’ve asked my doctor for results of any imaging tests.
• I have a copy of my biopsy or pathology report.
• I know the stage or location of my mesothelioma.
• I’ve spoken to a mesothelioma specialist.

Next Step: If you’re unsure about any of these items, a Patient Advocate can help you take the next step with confidence.

Connect With a Patient Advocate

Can Mesothelioma Be Misdiagnosed?

Yes, mesothelioma is often misdiagnosed as lung cancer, pneumonia or other conditions because of its vague symptoms. Mesothelioma survivor Wendy M. Phillips tells us, “I went to the hospital with a swollen arm and was initially told I had a blood clot. Mesothelioma tumors were blocking my lymph nodes.”

Getting a second opinion from a mesothelioma specialist can prevent delays in treatment. Many oncologists haven’t seen patients with mesothelioma before. They may misdiagnose mesothelioma or not consider it as a possible diagnosis. 

“Many patients we speak with have told us they were diagnosed after going to the hospital for what they thought was an unrelated symptom,” says Danielle DiPietro, a Patient Advocate at The Mesothelioma Center. The latency period between asbestos exposure and mesothelioma can be 20 to 60 years. Symptoms may not show up for decades. 

Importance of Early Mesothelioma Detection

Detecting mesothelioma early is vital. It lets doctors begin treatment sooner. This can lead to treatment success and better life expectancy. According to the Centers for Disease Control and Prevention, early mesothelioma detection isn’t common. Between 2017 and 2021, a total of 70.9% of mesothelioma diagnoses occurred after stage 1.

“After my surgery, I was told my mesothelioma was stage 1-B,” survivor Kevin Hession tells us. Doctors diagnosed him with pleural mesothelioma in 2021. This came after 4 instances of pleurisy (inflammation of the pleura). Ongoing chemo keeps his disease under control.

The experience of mesothelioma specialists is invaluable. General health care providers might not have the skills for complete care. Early detection from a mesothelioma specialist can help people live longer and enjoy a better quality of life.

A specialist helped peritoneal survivor Tamron Little. “At first, I was under the care of an oncologist who said he knew nothing about mesothelioma. But I finally found the right mesothelioma specialist. I was presented with a roadblock and decided to go around it.”

What to Do After a Mesothelioma Diagnosis

A mesothelioma diagnosis can be overwhelming, but Patient Advocates can help patients navigate treatment, legal options and support resources. Seeing a mesothelioma specialist is crucial.

Next Steps After a Mesothelioma Diagnosis

1. Meet with a mesothelioma specialist
2. Inquire about eligibility for surgery, chemotherapy and immunotherapy
3. Consider second opinions and clinical trials
4. Get support from patient advocacy groups
5. Explore legal options for legal compensation

Many doctors lack experience in diagnosing and treating mesothelioma. Sometimes, they get the stage or cell type wrong. A second opinion from an expert is useful if you get a diagnosis from a nonspecialist. They can confirm the diagnosis. You’ll also have access to new therapies and clinical trials.

“Most people who contact us about diagnosing mesothelioma are looking for a second opinion,” says Patient Advocate Dr. Snehal Smart. “We can connect them with treatment specialists and arrange appointments and treatment if they do receive a confirmed mesothelioma diagnosis.”

Common Questions About Diagnosing Mesothelioma

Who should be tested for mesothelioma?

Long-term asbestos exposure creates the greatest risk of a mesothelioma diagnosis. If you have a history of asbestos exposure, talk to your doctor and watch for symptoms. A cough, shortness of breath and chest pain tend to develop first. See your primary doctor if you develop new symptoms. Families of asbestos workers face secondary exposure. This can also cause mesothelioma.

How long does it take to get a mesothelioma diagnosis?

About 3 months is the average time it takes to get a mesothelioma diagnosis. This is after the first symptoms appear. The most common symptoms include shortness of breath and chest pain.

How do you prepare for a mesothelioma biopsy?

The first step in preparing for a mesothelioma biopsy is to stop all blood-thinning meds at least 5 days before your biopsy. Don’t eat or drink anything 6 hours before your appointment. Wear loose clothes to the appointment. Also, arrange for a designated driver to take you home.  Plan to spend several hours undergoing the biopsy. Some biopsies need at least one night in the hospital.

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