Medically Reviewed by: Dr. Zoe Owrutsky, PhD | January 23rd, 2026
Hearing the words mesothelioma diagnosis, or waiting for answers while experiencing concerning symptoms, can be an emotionally taxing time. Many people feel uncertain, frightened, or confused about what comes next. Diagnosing mesothelioma is a multi-step process that involves several different tests, each playing an important role in confirming the disease and guiding treatment decisions.
A mesothelioma diagnosis can be difficult to confirm. It is a rare cancer from asbestos exposure, with only about 3,000 people being diagnosed each year in the United States, and it often develops 20 to 50 years after asbestos exposure. Because of this long latency period, many patients no longer remember, or may not realize, that they were ever exposed to asbestos.
Adding to the challenge, early symptoms of mesothelioma frequently resemble more common conditions such as pneumonia, lung cancer, or irritable bowel disorders. Shortness of breath, chest pain, abdominal swelling, fatigue, or digestive discomfort are, more often than not, symptoms of less serious illnesses. Because of this overlap, many patients experience delays or misdiagnosis before receiving a definitive answer.
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The process of diagnosing mesothelioma can take weeks to months from the onset of symptoms to a confirmed diagnosis, as early symptoms are often vague and additional specialist evaluation may be required. Diagnosis also normally follows a specific pathway:
Symptoms → physician evaluation → imaging scans → blood tests → biopsy confirmation
Doctors rely on several categories of testing to evaluate and confirm mesothelioma:
No single test can diagnose mesothelioma on its own. Imaging studies may suggest disease, but a pathology-based diagnosis using biopsy or cytology with immunohistochemical testing (a laboratory technique that uses antibodies to detect specific proteins in tissue samples) is typically required for confirmation. According to the American Cancer Society, diagnosing mesothelioma often involves multiple specialized tests due to the disease’s rarity and complexity.
When mesothelioma is identified earlier, patients may have access to a broader range of treatment options. Earlier diagnosis can allow care to begin sooner, which may be associated with improved outcomes.
As you begin scheduling diagnostic tests, it’s also a good idea to contact your insurance provider. Many mesothelioma diagnostic tests are covered by Medicare or health insurance, and understanding your coverage early can help avoid surprises.
Imaging is usually the first step in mesothelioma testing after a physician suspects something abnormal. These scans help doctors visualize internal changes, identify suspicious areas, and evaluate whether cancer may have spread.
While imaging tests are essential, they can’t confirm mesothelioma on their own. Instead, they guide doctors toward the most appropriate biopsy method and assist with disease staging.
X-rays are often the first imaging test used when mesothelioma is suspected. These low-radiation, two-dimensional images can reveal:
X-rays are non-invasive, typically take 10–15 minutes, and are widely available. While they may reveal abnormalities that raise concern, X-rays don’t provide enough detail to confirm a mesothelioma diagnosis and are usually followed by more advanced imaging.
CT scans are the most commonly used imaging test for mesothelioma. They produce detailed cross-sectional images that help doctors determine the exact size, shape, and location of tumors.
Many patients ask, “What does mesothelioma look like on a CT scan?” Doctors often look for irregular pleural thickening, nodules along the lung lining, and fluid accumulation. CT scans typically take 10–30 minutes and may involve the use of contrast dye to enhance image clarity.
CT scans are also used to guide biopsy procedures and evaluate whether cancer has spread beyond its original site.
Positron emission tomography (PET) scans can help detect cancer by showing how active cells are (metabolic activity). A small amount of radioactive tracer is injected into the bloodstream, and cancer cells absorb more of it because of their higher metabolic activity.
PET scans are most often used for staging mesothelioma and identifying whether cancer has spread to lymph nodes or distant organs. Patients usually wait about an hour after the injection, followed by a 30- to 60-minute scan. PET scans are often combined with CT scans to provide a more complete picture.
Magnetic resonance imaging (MRI) scans use magnetic fields rather than radiation to create detailed images of soft tissue. These scans are especially helpful for assessing local tumor extent, surgical planning, and evaluating tumor involvement in nearby structures, such as the chest wall, diaphragm, or spine.
MRIs typically last between 15 and 60 minutes and may be uncomfortable for patients with claustrophobia. They are particularly useful in diagnosing and evaluating peritoneal mesothelioma.
A mesothelioma blood test can support diagnosis, but can’t confirm it alone. Blood tests measure biomarkers (substances in the blood that may indicate the presence of cancer) and are often used alongside imaging and biopsies.
One commonly used test is SMRP (Soluble Mesothelin-Related Peptides), marketed as Mesomark.
Approved by the U.S. Food and Drug Administration (FDA) in 2007, this test measures mesothelin proteins released by certain mesothelioma cells. It’s approved for monitoring disease status and response to treatment, but it can’t establish an initial diagnosis on its own. It’s most useful for epithelioid mesothelioma and less effective for sarcomatoid subtypes.
Another test, CA-125, isn’t specific to mesothelioma but can help assess disease burden, monitor treatment response, and track progression, according to the Mayo Clinic. Doctors use blood tests as valuable tools, but confirming a diagnosis requires further testing.
Confirming a mesothelioma diagnosis requires a biopsy. A mesothelioma biopsy is the only definitive way to diagnose mesothelioma and determine its cell type, which directly affects treatment options and prognosis.
During a biopsy, doctors remove tissue and/or fluid samples that pathologists examine using immunohistochemistry. This testing identifies specific cellular markers, such as calretinin and cytokeratin 5/6, to distinguish mesothelioma from other cancers.
Doctors typically begin with the least invasive biopsy method and progress if results are inconclusive. There are three main types of biopsies, ranging from minimally invasive to surgical procedures: needle biopsies, camera-assisted biopsies, and surgical biopsies.
Needle biopsies are often the first biopsy method used to evaluate suspected mesothelioma. These procedures are minimally invasive, commonly performed on an outpatient basis, and usually allow for same-day discharge. Image guidance, through ultrasound or CT scanning, helps doctors accurately target the area being sampled.
Common needle biopsy procedures include:
Most patients recover quickly from needle biopsies and experience minimal discomfort. However, because these procedures collect limited tissue or fluid samples, they may not always provide enough material to confirm a diagnosis or determine cell type. If results are inconclusive, doctors may recommend additional testing. Needle biopsies are most commonly used in cases of pleural mesothelioma, where fluid buildup is often present.
Camera-assisted biopsies are typically recommended when needle biopsies don’t provide sufficient tissue for an accurate diagnosis or when a more definitive sample is needed. These procedures allow doctors to visually examine the affected area and collect larger, more targeted tissue samples.
During a camera-assisted biopsy, surgeons make small incisions and insert a thin camera along with specialized instruments. These procedures are performed under general anesthesia and offer greater precision than needle-based methods.
Common camera-assisted biopsy procedures include:
Because these methods allow direct visualization, they often yield higher-quality samples, improving diagnostic accuracy. Recovery usually takes several days, and patients may experience temporary soreness or fatigue. Camera-assisted biopsies are an important step when confirming mesothelioma and assessing local disease involvement.
Surgical biopsies are the most invasive diagnostic option and are now used less commonly for diagnostic purposes alone. They are generally reserved for situations where needle and camera-assisted biopsies have failed to provide a clear diagnosis or when a larger tissue sample is needed.
Procedures such as thoracotomy (chest) or laparotomy (abdomen) require general anesthesia and a hospital stay. In some cases, surgeons may remove part or all of a visible tumor during the procedure, which can also help relieve symptoms or assist with staging and treatment planning, though these procedures aren’t primarily performed as curative surgery.
Recovery from surgical biopsies can take several weeks and may involve a longer healing period compared to other biopsy methods. Despite this, surgical biopsies provide the most comprehensive tissue samples, which can be critical for rare, complex, or diagnostically uncertain cases. Advances in imaging and minimally invasive techniques have reduced the need for surgical biopsies, but they remain an important option when other methods are insufficient.
Not sure what your test results mean?
If you or a loved one has been diagnosed with mesothelioma, our free mesothelioma guide can help explain diagnostic terms, treatment options, and next steps in clear, plain language. Get your free mesothelioma guide today.
A confirmed mesothelioma diagnosis provides several important pieces of information that help your medical team understand the disease and plan your care. While the terminology can feel overwhelming at first, each part of the diagnosis plays a specific role in guiding treatment decisions and setting expectations.
Your diagnosis typically includes:
Together, this information helps doctors determine which treatments may be most effective and whether surgery, chemotherapy, radiation, immunotherapy, or a combination of approaches may be appropriate. Cell type, in particular, can influence how the cancer responds to treatment and may affect prognosis.
To reach these conclusions, pathologists rely on immunohistochemistry testing. These markers help distinguish mesothelioma from other cancers with similar appearances, ensuring the diagnosis is as accurate as possible.
For many patients, the time from the first appearance of symptoms to a confirmed diagnosis can take weeks to months, though timelines vary depending on symptoms, access to specialists, and testing needs. Learning more about what mesothelioma is, mesothelioma staging, and common symptoms can help patients and caregivers better understand what the diagnosis means and prepare for the next steps with greater confidence.
Once you receive your mesothelioma diagnosis, the steps below can help you feel more prepared and supported as you begin the next phase of care:
Being diagnosed with mesothelioma can be life-altering. It’s normal to experience a wide range of emotions, including fear, anger, grief, and uncertainty about the future. Many people also feel overwhelmed by the amount of information they are suddenly expected to absorb. Taking things one step at a time can make the process feel more manageable.
After a diagnosis, many patients focus on a few key next steps:
Trusted medical centers such as the Mayo Clinic emphasize the importance of specialist care and coordinated treatment planning, particularly for rare cancers like mesothelioma. Having a knowledgeable care team can help ensure that all aspects of your health and well-being are addressed.
Our free mesothelioma guide can also help you better understand your diagnosis, available treatments, and practical next steps, all in one place. While the road ahead may feel uncertain, the right information, expert care, and support can help you move forward with greater clarity, confidence, and a sense of control.
Lauren is a copywriter dedicated to producing clear and trustworthy content for patients and their families. With a focus on accuracy and accessibility, Lauren works to make complex medical information easier to navigate and understand.
Zoe earned her Bachelor of Science from the University of Pittsburgh in 2014 and her Ph.D. in neuroscience from the University of Colorado Anschutz Medical Campus in 2023. As a neuroscience researcher, she studied the pathophysiology of depression and schizophrenia and worked toward developing translational biomarkers for spatial hearing ability. She is passionate about mental health advocacy and science communication.
American Cancer Society. Key Statistics for Malignant Mesothelioma.
https://www.cancer.org/cancer/types/malignant-mesothelioma/about/key-statistics.html. Accessed January 2026
Mayo Clinic. Mesothelioma – Diagnosis and Treatment.
https://www.mayoclinic.org/diseases-conditions/mesothelioma/diagnosis-treatment/drc-20375028. Accessed January 2026
Mayo Clinic. “CA-125 Test.”
https://www.mayoclinic.org/tests-procedures/ca-125-test/about/pac-20393295.
Accessed January 2026
U.S. Food and Drug Administration (FDA). Mesomark (Soluble Mesothelin-Related Peptides) Test Approval. https://www.accessdata.fda.gov/cdrh_docs/pdf6/P060040c.pdf.
Accessed January 2026