How to Test for Mesothelioma
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Insights: How to Test for Mesothelioma

We actually have this amazing brochure that we can send to a patient that thinks they might have mesothelioma, never been to a doctor before, never been diagnosed. We offer a brochure they literally can take to the doctor's office with them and literally hand it to the doctor and say, I think I have this. Can I have these tests?

The first test for a patient with, symptoms related to mesothelioma will be going to their primary doctor, getting an x-ray or a CAT scan done. Based on the results from that, they may go through further testing such as a thoracentesis or paracentesis, which is where they drain fluid, whether it's from the lining of the lungs or the peritoneal area, which is the abdominal area. The next step would be for a biopsy. The biopsy is a step where they confirm the diagnosis. This sample is sent to a pathologist who ultimately tests the sample taken out from the tumor and identifies it as mesothelioma.

And not just look at under microscope by any pathologist, but pathologist who has an expertise in making that diagnosis. Because even with a good sample of tumor, looking at it under a microscope, it can sometimes be difficult to make that diagnosis. And it's important not only to know that it's mesothelioma, it's important to know what is the histological subtype. Is it epithelial or is it sarcomatoid or is it a mixture of both called mixed or biphasic, because that changes the type of treatment.

We handhold them through the diagnostic part early on. So we actually prepare them before they go of what their doctor is likely going to do or what may not need to do based on their previous studies they've had.


However, those symptoms can also and much more often be indicative of other problems, such as lung cancer, infections, heart failure, liver problems. So just because your doctor told you that you have fluid around the lung does not necessarily mean you have mesothelioma.

Even if you have an asbestos exposure, you need to look further into it. You need to have the fluid drawn and sent for analysis. And most of the time that's not enough because looking for mesothelial cells in the pleural fluid and the fluid around the lung sometimes doesn't give you an answer. In fact, the majority of the time it does not make a diagnosis of mesothelioma. Very often you need a surgical biopsy or core biopsy to make sure that you indeed have mesothelioma. I'm glad to say most patients with fluid around the lung do not have mesothelioma, don't even have cancer. They very often have inflammation or infection.

How Is Mesothelioma Diagnosed?

For many people, mesothelioma diagnosis begins with a physical exam when symptoms appear. For those with a known history of asbestos exposure, screening tests may begin even before signs of mesothelioma develop. For others, mesothelioma is sometimes found incidentally during tests or procedures for unrelated conditions. However it’s detected, doctors typically use a combination of imaging tests, blood tests, fluid analysis and biopsies to confirm this rare cancer.

Key Tests to Diagnose Mesothelioma

  • Biopsies: Common procedures for collecting tissue or tumor samples include core needle biopsy, thoracoscopy with VATS, laparoscopy and mediastinoscopy.
  • Blood tests: These can show unusual blood cell counts and some mesothelioma markers, but can’t detect mesothelioma cancer cells.
  • Fluid analysis: Fluid removed through procedures like thoracentesis and paracentesis can be analyzed for mesothelioma cells.
  • Imaging tests: PET scans, X-rays, CT scans and MRIs show tumor size, location and spread, helping identify the stage of cancer progression.
  • Medical history and physical exam: Your doctor will review your full history and perform a physical exam to identify signs of mesothelioma.

Once your doctor suspects mesothelioma, they’ll typically refer you to an oncologist. From there, you can expect imaging tests to determine where tumors are located and how far they’ve spread, and your oncologist will also listen for signs of fluid buildup. Because mesothelioma symptoms resemble those of other conditions, getting the right specialists involved early matters.

A biopsy is the most important step in confirming a diagnosis. Only a biopsy and its resulting pathology report can identify mesothelioma with certainty. A pathologist examines the tissue sample under a microscope and documents the specific cell type present. Whether cells are epithelioid, sarcomatoid or biphasic directly shapes your prognosis and treatment options.

Process of how mesothelioma is diagnosed
Doctors use biopsies, physical exams, imaging tests and blood tests to diagnose mesothelioma.

Medical History and Physical Exam

If you have chest pain, trouble swallowing, shortness of breath or back pain and believe you’re at risk for mesothelioma, see your doctor. You could be at risk if you’ve worked in construction, shipbuilding or military service, or lived with someone who worked with asbestos products. Your doctor will discuss your medical history and ask about your asbestos exposure.

Then, your doctor will do a physical exam, checking for symptoms of mesothelioma, such as fluid buildup in your chest (pleural effusion) or in your belly (ascites). They’ll check for fluid around your heart (pericardial effusion). In rare cases of testicular mesothelioma, they’ll perform a physical examination of the groin area.

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Imaging Tests for Mesothelioma

Radiologists use mesothelioma imaging tests, including PET scans, X-rays, echocardiograms, CT scans and MRIs, to locate and assess mesothelioma tumors. Imaging tests can show tumor size, location and possible spread, but they can’t confirm mesothelioma on their own. Doctors use scan results to decide where to take tissue samples during a biopsy. 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 scans: CT scans produce high-resolution cross-sections with detailed views of possible tumors in the chest and abdomen.
  • Echocardiograms: A noninvasive procedure, echocardiograms use ultrasound to create an outline of the movement of the heart.
  • Magnetic resonance imaging scans: MRIs use a strong magnetic field and radio waves to form detailed images of the person’s soft tissues.
  • Positron emission tomography 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.

The day I found out I was diagnosed with mesothelioma, I was pretty scared. I was shocked. I was in shock. I felt like I was in the Twilight Zone. When they told me I was diagnosed with mesothelioma, no one knew what it was. I didn’t know what it was. My mom, my husband, no one. It was the day my whole life changed.

Tamron Little
Tamron Little , peritoneal mesothelioma survivor

Blood Tests

Doctors sometimes order blood tests as part of the mesothelioma testing process. These tests look for certain proteins, white blood cell levels and other possible signs called biomarkers. Because these markers can be associated with other conditions too, blood tests can suggest mesothelioma but can’t confirm it on their own.

Fibulin-3 is a protein your body makes to help build and support connective tissues. Mesothelioma cells can release extra fibulin-3, which leads to higher levels in the blood. But higher levels can also show up with other cancers like cervical cancer.

Similarly, the MESOMARK blood test looks for molecules called soluble mesothelin-related peptides. Mesothelioma cells make SMRPs. But SMRPs have also been found in ovarian and pancreatic cancer. Doctors use blood tests like MESOMARK, N-ERC/mesothelin and fibulin-3 to get clues, but they need a biopsy to confirm a mesothelioma diagnosis.

Researchers are also studying new types of tests. In 2025, the American Society of Clinical Oncology started to recommend genetic testing. Genetic testing often involves blood and saliva tests. A 2024 review reports up to 10% of patients diagnosed with mesothelioma have what’s known as a BAP1 mutation. They tend to respond better to chemotherapy. Patients with this mutation have a median survival of 5 years.

What’s the Next Step in Confirming Your Mesothelioma Diagnosis?

Tell us where you are in your diagnosis process and we’ll help you figure out your next steps.

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Have you written down your symptoms and when they started (e.g., breathlessness, chest/abdominal pain, swelling)?
Have you seen a primary care or local doctor about these symptoms?
Have you told a doctor about any possible asbestos exposure (work, military, home, or secondary exposure)?
Have you had imaging scans (X-ray, CT or MRI) for these symptoms?
Have you met with a mesothelioma specialist (thoracic or surgical oncologist with mesothelioma expertise)?
Has a biopsy been performed to confirm the diagnosis?
Do you have your pathology report and know the cell type?
Have you sought a second opinion?
Do you have copies of your scans, pathology, and a list of questions for your next appointment?

Diagnosis Readiness

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    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 around the heart. Then, they use a microscope to search for mesothelioma cells. If they find these 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.

    Both 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 look at fluid, while biopsies take tissue samples. Biopsies give more information about cancer cells, which is how doctors determine whether you have mesothelioma.

    Biopsies

    A biopsy is the best test for confirming a mesothelioma diagnosis. This medical procedure takes a sample of tissue that’s studied 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. Because fluid tests alone often cannot confirm mesothelioma, a tissue biopsy is essential for an accurate diagnosis and for determining the cell type and stage of the disease.

    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.
    • Core 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: Surgeons make a larger cut to remove a tissue sample when other methods don’t work. This is used when an endoscopic or core needle biopsy isn’t possible.
    • Thoracoscopy: Doctors make a small cut in the chest, then use a tube with a camera to examine and take tissue. This is the most accurate biopsy for diagnosing pleural mesothelioma. Laparoscopy and mediastinoscopy, may be used depending on where the tumor develops.

    Thoracic surgeon Dr. Jeffrey Velotta tells us, “The diagnosis of mesothelioma is very difficult. Fluid, the majority of the time, 70% to 80% of the time will not tell you if you have mesothelioma or not. There’s just not enough cells in the fluid. You actually need tissue. I recommend all patients undergo biopsy as soon as possible and not wait.”

    Mesothelioma Cell Types and Diagnosis

    When pathologists examine biopsy tissue under a microscope to confirm mesothelioma, they also identify the specific cell type. It’s a key part of a mesothelioma diagnosis because cell type affects prognosis and which treatments are most likely to work.

    Mesothelioma Cell Types Identified Through Biopsy

    • Biphasic: A mix of epithelioid and sarcomatoid cells, found in 20% to 35% of cases. Treatment outcomes depend on the proportion of each cell type.
    • Epithelioid: The most common cell type, found in 50% to 70% of cases. People with epithelioid mesothelioma typically have the best prognosis and respond well to surgery and chemotherapy.
    • Sarcomatoid: The rarest and most aggressive cell type, found in 10% to 20% of cases. Sarcomatoid mesothelioma is harder to treat with surgery.

    Dr. Jacques Fontaine, thoracic surgeon at Moffitt Cancer Center and medical reviewer for this page, tells us, “It’s important not only to know that it’s mesothelioma, it’s important to know what is the histological subtype. Is it epithelial or is it sarcomatoid or is it a mixture of both called mixed or biphasic? Knowing more about the tumor will allow us to find the right treatment for that tumor.”

    Staging Mesothelioma Cancer

    Mesothelioma staging is part of the diagnostic process. It describes how far tumors have spread, which can be seen on imaging scans. 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.

    Staging helps doctors plan the best treatment. An early-stage diagnosis improves treatment options. A late diagnosis makes these treatments less effective. Later stages become more difficult to treat.

    The TNM staging system is the official method for staging pleural mesothelioma. It describes tumor size, lymph node involvement and cancer spread to distant organs, helping doctors plan the most effective treatment. The current standard is the 9th edition of the TNM Classification for Pleural Mesothelioma, updated in 2024.

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

    Mesothelioma Patient Diagnoses by Stage
    Stage at Diagnosis % of Respondents
    Stage 1 12%
    Stage 2 17%
    Stage 3 23%
    Stage 4 48%
    Source: The Mesothelioma Center’s 2025 Survivor & Caregiver Survey

    Why Is Diagnosing Mesothelioma Difficult?

    Diagnosing mesothelioma is difficult because its symptoms mimic more common illnesses like bronchitis or pneumonia. The latency period between asbestos exposure and mesothelioma can be 20 to 60 years. So when symptoms show up decades later, an asbestos-related disease like mesothelioma may not immediately come to mind.

    Mesothelioma misdiagnosis is unfortunately common. Many people are first told they have pneumonia, COPD, lung cancer or heart problems before doctors identify mesothelioma. On average, it usually takes about 3 months from their first symptoms to getting a confirmed diagnosis. Because many doctors are unfamiliar with this rare malignant cancer, getting a second opinion from an asbestos-related cancer expert is so important if you’ve had a history of asbestos exposure. But some people aren’t aware they’ve been exposed, making it even more challenging.

    Patient Advocate and VA-accredited claims agent Danielle DiPietro tells us, “Many patients we speak with have told us they were diagnosed after going to the hospital for what they thought was an unrelated symptom.”

    Mesothelioma survivor Wendy M. Phillips confirms this was the case for her. She 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.”

    Importance of Early Mesothelioma Detection

    Finding mesothelioma early is very important because it allows doctors to start treatment sooner. An early diagnosis and guidance from a mesothelioma specialist can offer more treatment options and better outcomes. This can improve survival and quality of life.

    However, according to the Centers for Disease Control and Prevention, early detection is still rare. From 2017 to 2021, 70.9% of mesothelioma cases were diagnosed after stage 1.

    Pleural mesothelioma survivor Kevin Hession is an unusual example of someone diagnosed early. He tells us, “After my surgery, I was told my mesothelioma was stage 1-B.” His diagnosis in 2021 followed 4 cases of pleurisy, which is inflammation around the lungs. Ongoing chemotherapy is helping him manage the disease.

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    What to Do After a Mesothelioma Diagnosis

    Once you receive a mesothelioma diagnosis, it’s important to begin planning your mesothelioma treatment with your doctor. Often in this process, people have questions about and want another perspective on the best treatment for them. Getting a second opinion from an expert can make you aware of other approaches, new therapies or available clinical trials. Because mesothelioma is rare, consulting a mesothelioma specialist reduces the risk of misdiagnosis and ensures access to the latest treatment options.

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

    Next Steps After a Mesothelioma Diagnosis

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

    Peritoneal mesothelioma survivor Tamron Little knows the importance of a second opinion firsthand. She shares with us, “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.”

    A mesothelioma diagnosis can feel overwhelming, but you don’t have to go through it alone. Patient Advocates help people understand treatment options, schedule appointments, navigate insurance and explore financial support for medical expenses.

    Asbestos.com Expert Takeaway
    Expert Takeaways for Diagnosis

    Patients with a history of asbestos exposure or symptoms such as persistent cough, chest pain or shortness of breath should seek medical evaluation immediately.


    “Making an accurate mesothelioma diagnosis can be tough. The initial signs on imaging can be nonspecific. Misdiagnosis can occur. It’s important to tell mesothelioma apart from other cancers that can spread to the pleura. The treatments are very different based on an accurate diagnosis.”
    Catherine Perrault headshot

    Dr. Catherine Perrault, medical officer and board-certified family physician with The Mesothelioma Center’s Medical Outreach Team

    Common Questions About Diagnosing Mesothelioma

    Who should be tested for mesothelioma?

    People with a history of asbestos exposure and symptoms such as chest pain or shortness of breath should ask their doctor about testing for mesothelioma. They may recommend imaging scans, blood tests and a biopsy to diagnose 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.

    What test confirms mesothelioma?

    Only a biopsy can confirm mesothelioma. A doctor removes a small piece of tissue from the tumor and sends it to a pathologist, who examines it under a microscope and identifies the cell type. Imaging scans, blood tests and fluid analysis can suggest mesothelioma but can’t confirm it on their own. Doctors often recommend a second pathology opinion from a specialist before starting treatment.

    Can mesothelioma be misdiagnosed?

    Yes, mesothelioma is often misdiagnosed because its early symptoms like cough, chest pain and shortness of breath look like more common conditions such as pneumonia, COPD, lung cancer or heart problems. The average person waits about 3 months for an accurate diagnosis and many see several doctors first. A history of asbestos exposure and a tissue biopsy reviewed by a specialist pathologist are the best ways to avoid misdiagnosis.

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