Written By: Devin Golden
Mesothelioma Cytology
Mesothelioma cytology can be used in the diagnosis of mesothelioma, which is a rare and aggressive type of cancer. Cytology involves examining cells from fluid samples under a microscope to look for features suggestive of malignant mesothelial transformation.
Medically Reviewed By
Dr. Stephen Williams
Precision Oncology Scientist
Medically Reviewed By
Dr. Stephen Williams
Precision Oncology Scientist
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What Is Mesothelioma Cytology?
Mesothelioma cytology is the study of individual cells or clusters of cells from fluid extracted from the body. Cytology along with cytopathology, a subspeciality of pathology, are used to determine if the cells are normal or abnormal, and if cancer like mesothelioma is present.
Cytology is one component of mesothelioma pathology, which encompasses the analysis of both tissue and fluid specimens.
The most notable characteristics of mesothelioma cytology are:
- Often less invasive process than a tissue biopsy
- A small incision or needle to collect fluid, often from chest, abdomen, or near the heart
- Minimal to no scarring at the collection site
- Typically does not require general anesthesia
- Easier and faster to obtain samples
- May cost less compared with surgical or tissue biopsies
- Less reliable for diagnosis than a tissue biopsy
- Limited cellular material, making interpretation more challenging
How Is Mesothelioma Cytology Performed?
Mesothelioma cytology starts with a procedure to remove fluid from the patient’s body. Doctors often need to remove excess fluid from around the lungs (pleural fluid) or abdominal cavity (ascites) due to pain or difficulty breathing caused by mesothelioma tumors. After the fluid is removed, it is sent to the pathology lab for evaluation.
If cancer is suspected on imaging scans, the next step is obtaining a mesothelioma biopsy. A tissue biopsy is the most reliable way to get a definitive diagnosis of mesothelioma, although there are times when a fluid sample provides enough evidence.
How Are Fluid Samples Collected?
Fluid samples are collected through a small catheter or needle. A fine-needle aspiration uses a syringe with a thin needle to remove fluid from a suspected tumor area.
There are multiple procedures to remove fluid for mesothelioma cytology. They differ based on where tumors are found. Biopsies performed to collect fluid samples are:
The non-surgical biopsies used to collect fluid samples are:
- Thoracentesis — Removes fluid from the pleura or chest cavity to diagnose pleural mesothelioma
- Paracentesis — Removes fluid from the peritoneum or abdominal cavity to diagnose peritoneal mesothelioma
- Pericardiocentesis — Removes fluid from the pericardium (surrounds the heart) to diagnose pericardial mesothelioma
Patients with mesothelioma often experience fluid buildup in the space where this cancer forms. This fluid is described as:
These symptoms are:
- Pleural effusions – Excess fluid in the pleura, which is between the lung and chest wall
- Ascites – Excess fluid in the peritoneum, in the lining of the abdomen
- Pericardial effusions – Excess fluid in the pericardium, the lining around the heart
The removed fluid is sent for mesothelioma cytology and analyzed by a pathologist. The cytology report, also called a pathology report, will provide detailed findings of the fluid and cells. If there is enough cellular information in the fluid sample, it may provide a mesothelioma diagnosis.
How Do Doctors Test Fluid Samples?
Testing fluid samples for mesothelioma depends on the sample’s cellularity and blood content. Low-cell-count specimens may require high-magnification microscopy, while blood-contaminated samples are often treated with solutions such as saline to reduce interference and improve cellular visualization.
The fluid is then processed, placed on glass slides, and stained with cytologic dyes that highlight cellular features associated with malignancy. The most commonly used stains in mesothelioma cytology include:
- Diff-Quik
- Papanicolaou (Pap)
- May-Grünwald-Giemsa
Microscopic Fluid Sample
The three most common stains for mesothelioma cytology are:
- Diff-Quik
- Papanicolaou
- May-Grünwald-Giemsa
These stains accentuate differences in cell size, shape, nuclear detail, and cytoplasmic features. Pathologists examine the stained slides under a microscope to assess whether malignant mesothelial cells are present.
Based on cellular morphology and staining patterns, pathologists may also infer the mesothelioma cell subtype. Cytology is most informative for epithelioid mesothelioma, which accounts for approximately 50-70% of cases and has more distinct, recognizable cellular features. In contrast, sarcomatoid mesothelioma is less likely to be identified reliably in fluid samples, limiting cytology’s diagnostic sensitivity for this subtype.
Limitations of Mesothelioma Cytology
Cytology has important limitations when diagnosing mesothelioma and is not consistently reliable as a standalone diagnostic tool. Several factors contribute to these challenges:
- Too few cells in a sample — Not all fluid samples have an adequate amount of cells to examine. This makes it difficult to determine the presence of mesothelioma.
- Loss of tissue architecture — Cells suspended in fluid lack the organized structural patterns seen in tissue biopsies. As noted by Dr. Elliot Wakeam, a thoracic oncologist at Michigan Medicine, cytologists often struggle to evaluate “the architecture of individual cells suspended in fluid,” which limits diagnostic precision.
- Not reliable for determining all cell types — Cytology is most effective for identifying epithelioid mesothelioma but performs poorly at identifying the sarcomatoid cell type. Evidence also shows that fluid samples are unreliable for diagnosing biphasic mesothelioma, which is a mixture of both the sarcomatoid and epithelioid cell types.
How to Get an Accurate Mesothelioma Diagnosis
If cytology results are inconclusive, the doctor will likely need a tissue biopsy to get a definitive mesothelioma diagnosis. Camera-assisted tissue biopsies, according to one study published on UpToDate, had 98% accuracy in diagnosing mesothelioma. Fluid biopsies were only accurate in 26% of cases.
Most pathologists are reluctant to provide a definitive diagnosis solely on a fluid sample. Tissue biopsies are the most reliable way to determine a diagnosis of mesothelioma.
Mesothelioma Guide suggests patients contact a specialist with a cancer center to get an accurate diagnosis. Email registered nurse Karen Ritter at karen@mesotheliomaguide.com for her recommendations on specialists near you.
Sources & Author
- How Cytopathology Works. VeryWellHealth. Retrieved from: https://www.verywellhealth.com/cytopathology-2252146. Accessed: 05/06/2020.
- What Is Histopathology? VeryWellHealth. Retrieved from: https://www.verywellhealth.com/histopathology-2252152. Accessed: 05/06/2020.
- Tests for Malignant Mesothelioma. American Cancer Society. Retrieved from: https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/how-diagnosed.html. Accessed: 05/05/2020.
- Guidelines for cytopathologic diagnosis of epithelioid and mixed type malignant mesothelioma. Complementary statement from the International Mesothelioma Interest Group, also endorsed by the International Academy of Cytology and the Papanicolaou Society of Cytopathology. CytoJournal. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4678521/. Accessed: 05/11/2020.
- Diffuse malignant mesothelioma. Pathology Outlines. Retrieved from: http://www.pathologyoutlines.com/topic/pleuramesothelioma.html. Accessed: 05/11/2020.
- Presentation, initial evaluation, and prognosis of malignant pleural mesothelioma. UpToDate. Retrieved from: https://www.uptodate.com/contents/presentation-initial-evaluation-and-prognosis-of-malignant-pleural-mesothelioma?topicRef=4625&source=see_link. Accessed: 03/19/19.
- Comparison of outcomes following a cytological or histological diagnosis of malignant mesothelioma. British Journal of Cancer. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5355925/. Accessed: 05/11/2020.
AI Summary of Mesothelioma Cytology
Mesothelioma cytology is a medical procedure used in diagnosing mesothelioma, a rare and aggressive cancer often associated with asbestos exposure. This process involves examining cells collected from body fluids, such as those around the lungs, abdomen, or heart, to detect the presence of cancerous changes. Cytology offers a less invasive alternative to surgical biopsies, typically involving only a small needle or catheter to collect fluid samples, which can be obtained with minimal discomfort and scarring. While cytology can provide valuable information, it is generally considered a preliminary step, and a tissue biopsy often remains necessary to confirm a diagnosis. Nevertheless, cytology can be an important part of the diagnostic process, especially when used in conjunction with other tests and imaging studies.
The procedure begins with the removal of excess fluid, a common symptom of mesothelioma, from areas such as the chest cavity or abdomen. This is achieved through procedures like thoracentesis, paracentesis, or pericardiocentesis, depending on where the fluid accumulates. The collected fluid is then sent to a laboratory where it is processed, stained with specific dyes, and examined under a microscope. Pathologists analyze the cellular features, looking for signs of malignancy, such as irregular cell size, shape, or nuclear details. These observations help determine whether the cancer is epithelioid, which is the most common form of mesothelioma and usually easier to identify, or sarcomatoid, which tends to be less detectable with fluid samples. Despite its advantages, cytology has limitations, including the challenge of obtaining enough cells in some samples and difficulty in distinguishing all mesothelioma types. As a result, a tissue biopsy often provides a more definitive diagnosis when cytological results are inconclusive.
Understanding the capabilities and limitations of mesothelioma cytology is essential for patients and families facing this diagnosis. While it is a valuable tool for initial assessment, cytology alone cannot always confirm mesothelioma due to its limitations in cellular material and subtype identification. If fluid-based tests do not provide a clear diagnosis, doctors will often recommend a tissue biopsy for more precise results. Patients are encouraged to consult with specialists at reputable cancer centers who are experienced in diagnosing mesothelioma. Early and accurate diagnosis is crucial for determining the most effective treatment options and providing patients with a clearer understanding of their condition, offering reassurance and guidance through a challenging time.