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Mesothelioma Cytology

Mesothelioma cytology allows doctors to review a small sample of fluid or tissue under a microscope and see if a patient has cancer or not. Once the mesothelioma cytology sample has been properly studied, your diagnosis can be confirmed. Learn more about mesothelioma cytology and getting a diagnosis below.

Fact-Checked and Updated by: Jenna Tozzi, RN

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Can Mesothelioma Be Diagnosed on Cytology?

A lab assistant holding a test tube

Possibly, yes. Mesothelioma cytology (otherwise known as cytopathology) is the study of cancer cells within a small fluid or tissue sample to confirm a patient’s diagnosis.

If a cancer doctor suspects you have mesothelioma, they may request cytology tests to confirm the diagnosis. It’s likely that you’ll then undergo a minor procedure so doctors can extract a sample from your body.

Once the sample has been removed, pathologists (doctors that examine tissues and fluids) will look at it under a microscope and see what type of cancer (if any) you have.

If you or a loved one may have mesothelioma, Mesothelioma Hope can help you find top doctors who can confirm your diagnosis. These doctors may possibly use mesothelioma cytology tests to diagnose you, and from there, recommend treatments to help you live longer.

Learn more in our Free Mesothelioma Guide — packed with nearly 100 pages of information to help patients and families affected by this rare cancer.

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Types of Mesothelioma Cytology Tests

Doctors usually collect mesothelioma cytology samples with a needle through one of two procedures, depending on the location of the cancer within the patient’s body.

Mesothelioma cytology tests can be performed on the pleural space between the lung and chest or the heart sac, depending on which type of the cancer you may have. The cytology tests are slightly different as a result.


Thoracentesis is the procedure used to collect fluid from the lungs and can help diagnose pleural mesothelioma.

Did You Know?

People naturally build up about four tablespoons of lung fluid. However, pleural mesothelioma patients may have more fluid than this due to the cancer. This is called a pleural effusion.

Doctors can perform a mesothelioma pleural effusion cytology as cancerous cells can sometimes be found in the fluid that builds up.

For most patients, the procedure is a quick one and only takes 10 to 15 minutes. However, if a lot of fluid has built up, it can take longer.


Pericardiocentesis is a procedure used to collect fluid samples from the heart lining (pericardium). It may be used to diagnose pericardial mesothelioma.

During a pericardiocentesis, a needle is placed into the space between the two thin layers outside the heart, where fluid naturally exists.

A pericardiocentesis may also be used to remove any extra fluid that has built up between these layers, called pericardial effusion. Getting a pericardiocentesis takes approximately one hour.

Mesothelioma Cytology vs. Histology

Cytology is not the exact same thing as histology, though the two are closely related. Cytology and histology are both forms of pathology.

  • Cytology tests extract very small samples and pathologists look at individual cells or small groups of cells to confirm a mesothelioma diagnosis.
  • Histology is the study of larger samples of tissues to see if a patient has cancer or not. Doctors take a biopsy (where many types of cells may be present, including cancerous ones) to try and diagnose mesothelioma.

Benefits of Mesothelioma Cytology

Mesothelioma specialists may possibly have better results when drawing cytology samples, as they know exactly which parts of the body are most likely to collect mesothelioma cells.

Malignant mesothelioma cytology tests have a couple of other key benefits when compared to biopsies.

Benefits of mesothelioma cytology tests include:

  • There is a lower risk of complications.
  • They’re easier to perform (less invasive) than biopsies.
  • They’re less expensive.
  • Patients may be able to get results faster.
  • Patients remain relatively comfortable.

Therefore, mesothelioma cytology tests may be used to make a diagnosis first, with a biopsy recommended if the cytology results are inconclusive.

Challenges of Mesothelioma Cytology

Pathology has advanced significantly over the past couple of decades, but there are still challenges when using cells to identify mesothelioma.

  • Because cells mutate in different ways, and at different rates, even the same types of mesothelioma cells can look very different between patients.
  • Pathologists have to differentiate between many types of cancer that all have similar-looking cells. Malignant mesothelioma and adenocarcinoma are two different forms of cancer that often look similar, for example.
  • If mesothelioma cytology images are unclear (or if the cell sample size wasn’t large enough), a definitive diagnosis can’t be made. Another cytology sample or biopsy may need to be extracted in these cases.

While cytologists are getting better at diagnosing mesothelioma, there are still margins of error and misdiagnosis does occasionally occur. Patients who suspect a misdiagnosis should request a second opinion or a histology test.

Mesothelioma Hope can help you find skilled doctors to perform a cytology test or offer a second opinion. Use our Free Doctor Match to find top specialists in your area right now.

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Cytology Process for Diagnosing Mesothelioma

Once a mesothelioma cytology sample is collected from a patient, it sent to a laboratory for review.

Pathologists place the mesothelioma cytology samples onto slides, called smears, and then use a collection of dyes to help reveal the cells contained inside it. They will then examine the smear under a microscope, looking at the composition of the cells and also noting how the cells interact with various dyes.

Did You Know?

Pathologists are typically looking at the cells’ shapes and sizes and will also compare samples to reference slides or databases. This process can take hours but being able to compare live cells helps determine whether a patient has mesothelioma.

Mesothelioma cytology test results are often available within 1-2 days of collection.

Looking for Mesothelioma Cells Using Cytology

There are three types of mesothelioma cells that can be diagnosed using cytology tests.

  1. Epithelioid: The most common mesothelioma cell type and the easiest to treat.
  2. Sarcomatoid: A highly aggressive form of mesothelioma. This is the rarest cell type and most difficult to treat.
  3. Biphasic: Some tumors contain both epithelioid and sarcomatoid cells. In these cases, patients have biphasic mesothelioma.

These cell types directly impact a patient’s mesothelioma prognosis and treatment options.

What are the cytological features of mesothelioma?

The cytological features of mesothelioma vary by cell type when reviewed by cytologists. Epithelioid cells are shaped like squares while sarcomatoid cells are shaped like spindles. Even the way the cells stick together and multiply differs between each type.

Fortunately, pathologists are familiar with the characteristics of each cell type and can still make an accurate diagnosis by reviewing mesothelioma cytology tests. Learn about each cell type below.

Epithelioid Mesothelioma

The most common mesothelioma cell type, epithelioid (or epithelial) cells are recognized by cytologists because of their uniform and defined appearance. They contain a single nucleus and tend to grow slower than other cancerous cell types.

While epithelial cells multiply quickly, they have a tendency to lump together, which makes their overall tumor growth relatively slow. Patients diagnosed with epithelioid mesothelioma tend to have the best prognosis.

Sarcomatoid Mesothelioma

Sarcomatoid cells are spindly in shape, with fibrous-looking groups of cells. They sometimes have more than one nucleus and don’t form large clumps as epithelioid cells do. Instead, sarcomatoid cells tend to be smaller nodules that can quickly spread through the body.

Because of its ability to spread rapidly, sarcomatoid mesothelioma is highly aggressive and tends to have the worst prognosis (health outlook) of all three cell types.

Biphasic Mesothelioma

When both epithelial and sarcomatoid cells are found in a tumor, a patient has biphasic mesothelioma. Mesothelioma patients are actually more likely to have biphasic mesothelioma than just sarcomatoid cells, making it the second most common cell type.

The prognosis for biphasic mesothelioma typically depends on the percentage of epithelioid cells versus sarcomatoid cells, with higher concentrations of epithelioid cells having the best outcomes.

Doctors can recommend treatments no matter what cell type is found on a mesothelioma cytology test. However, you may want to know more after your diagnosis.

Download our 14 Questions to Ask Your Doctor Checklist to get the answers you need.

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Cytology of Mesothelioma: Help for Patients

Mesothelioma cytology tests remain a top way to help diagnose this rare and aggressive cancer. If you or a loved one was ever exposed to asbestos and now has possible mesothelioma symptoms like a cough or chest pain, ask your doctor about cytology tests.

The Mesothelioma Hope team can help you find doctors who can perform cytology tests or other exams to properly diagnose you. And if you’re worried about affording medical expenses, we can help too — patients diagnosed with mesothelioma are often eligible for financial compensation.

Learn about all the benefits available to you with our Free Mesothelioma Guide, shipped overnight.

Mesothelioma Cytology FAQs

What is mesothelioma cytology diagnosis?

Mesothelioma cytology tests allow doctors to see if cancer cells are in your body. This is crucial to making a diagnosis.

Cytology tests are similar to a biopsy (another test used to confirm a mesothelioma diagnosis) except a smaller sample will be removed.

What is looked at in a mesothelioma cytology test?

Doctors will look at either tissue or fluid samples when trying to diagnose mesothelioma using a cytology test.

For example, if doctors think you have pleural mesothelioma, they may extract fluid that’s built up in your lung lining. This is known as a mesothelioma pleural effusion cytology.

Or, if there’s a solid tumor, doctors may remove a tiny part of it. In either case, pathologists will review the sample under a microscope to see if cancer cells are present.

How can I get a mesothelioma cytology test?

Ask your doctor right away about a mesothelioma cytology test if you might have this cancer.

Mesothelioma can spread very quickly without treatment — but the only way to access treatment is by getting properly diagnosed.

If doctors think you have mesothelioma, they’ll recommend tests to help diagnose you. These may include mesothelioma cytology tests or biopsies.

Jenna TozziWritten by:

Director of Patient Advocacy

Jenna Tozzi, RN, is the Director of Patient Advocacy at Mesothelioma Hope. With more than 15 years of experience as an adult and pediatric oncology nurse navigator, Jenna provides exceptional guidance and support to mesothelioma patients and their loved ones. Jenna has been featured in Oncology Nursing News and is a member of the Academy of Oncology Nurse & Patient Navigators & the American Nurses Association.

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  1. Acta Cytologica. (n.d.). Guidelines for the Cytopathologic Diagnosis of Epithelioid and Mixed-Type Malignant Mesothelioma. Retrieved February 8, 2024, from
  2. American Cancer Society. (n.d.). Types of cytology tests used to look for cancer. Retrieved February 8, 2024, from
  3. American Cancer Society. (n.d.). What happens to biopsy and cytology specimens? Retrieved February 8, 2024, from
  4. Cleveland Clinic. (n.d.). Cytology (cytopathology): What it is & types. Retrieved February 8, 2024, from
  5. Johns Hopkins Medicine. (n.d.). (2019, November 22). Cytology. Retrieved February 8, 2024, from
  6. Johns Hopkins Medicine. (n.d.). Thoracentesis. Retrieved February 8, 2024, from
  7. Johns Hopkins Medicine. (n.d.). Pericardiocentesis. Retrieved February 8, 2024, from
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