Written By: Karen Ritter, RN BSN
Mesothelioma Cell Types
There are three main mesothelioma cell types: epithelioid, sarcomatoid and biphasic. They are the result of mesothelial cells mutating.
Medically Reviewed By
Dr. Hassan Khalil
Mesothelioma Thoracic Surgeon
Medically Reviewed By
Dr. Hassan Khalil
Mesothelioma Thoracic Surgeon
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Important Facts About Mesothelioma Cell Types
- Epithelioid mesothelioma occurs most often, in roughly 70% of cases.
- Sarcomatoid mesothelioma is the toughest cell type to treat.
- Biphasic mesothelioma is a combination of epithelioid and sarcomatoid cells.
- The cell type determines how aggressive the cancer is, which in turn affects how the mesothelioma is treated.
Cell Types of Mesothelioma
A mesothelioma cell can be epithelioid or sarcomatoid, which accounts for two of the mesothelioma cell types. These two cells often mix together to form a third type called biphasic mesothelioma.
All three mesothelioma cell types can be present in pleural mesothelioma and peritoneal mesothelioma. Pleural mesothelioma forms near the lungs. Peritoneal mesothelioma forms near the abdomen.
Epithelioid Mesothelioma
- Clearly defined clump of cells
- Pink cytoplasm
- Easier to identify and remove during surgery
- Cell type with best prognosis
Epithelioid mesothelioma is the most common mesothelioma cell type. It’s also the easiest variation to treat.
It accounts for between 50% and 70% of all mesothelioma cases, according to the American Cancer Society. This mesothelioma cell type is a cancerous mutation of epithelial cells.
According to data from numerous sources, this cell type comprises a little more than half of pleural mesothelioma cases and close to 75% of peritoneal mesothelioma cases.
The average life expectancy for epithelioid pleural mesothelioma is around 19 months, according to a study published in 2018.
A different study reported epithelioid peritoneal mesothelioma patients had a median survival of 55 months.
Sarcomatoid Mesothelioma
- Overlapping, irregular shape
- Enlarged, elongated structure
- Metastasize and spread quickly
- Most challenging prognosis of the three types of mesothelioma cells
Sarcomatoid mesothelioma is the rarest mesothelioma cell type, accounting for between 10% and 20% of cases.
Sarcomatoid mesothelioma is extremely rare for peritoneal mesothelioma. It comprises around 20% of cases involving pleural mesothelioma.
Sarcomatoid mesothelioma has an unfavorable prognosis. This is due to its ability to spread fast. The average prognosis is 8 months for sarcomatoid pleural mesothelioma and 13 months for sarcomatoid peritoneal mesothelioma.
Sarcomatoid mesothelioma cells have a similar histological makeup to sarcoma-type cancers. However, sarcomatoid mesothelioma is caused by genetically mutated epithelial mesothelial cells. Some epithelial cells will transform into a different type of cell, which become sarcomas when cancerous.
Biphasic Mesothelioma
- Combination of epithelioid and sarcomatoid cell types
- Prognosis varies depending on cell prevalence
- Second most common cell type diagnosis
- Cells clump together in separate groups
Biphasic mesothelioma is a mixed type of mesothelioma with both epithelioid and sarcomatoid cells present.
It makes up between 20% and 30% of cases. A biphasic diagnosis has close to the same rate of occurrence for pleural mesothelioma and peritoneal mesothelioma.
It has an average survival time of 13 months for both pleural mesothelioma and peritoneal mesothelioma. The prognosis for biphasic mesothelioma depends on the ratio of epithelioid cells to sarcomatoid cells.
If the tumors have more epithelioid cells, then the cancer is more treatable. If the tumors have more sarcomatoid cells, then the mesothelioma will be more difficult to treat.
Histology
Histology is the study of your body tissue’s cellular makeup. Histology is an important aspect of diagnosing mesothelioma.
When someone is suspected of having mesothelioma, doctors examine a tissue or fluid sample under a microscope. They do this to determine if the cells are cancerous. Samples are typically taken with either a biopsy (tissue) or fluid extraction.
Histopathological testing is the study of diseased tissues. Testing of antibodies and other proteins is used to determine if the cells are mesothelioma. Immunohistochemistry staining tests for antibodies and proteins. This helps doctors distinguish between the three cell types.
The three mesothelioma cell types each have a unique shape, size and appearance. Experienced mesothelioma specialists can distinguish between epithelioid, sarcomatoid and biphasic cell types.
There are also several other histologic subtypes which include desmoplastic, anaplastic, lymphohistiocytoid and well-differentiated papillary. However, these subtypes are very rare.
People should be cautious if they were diagnosed with cancers that histologically resemble mesothelioma, such as adenocarcinoma. If they were exposed to asbestos in the past, they should seek a second opinion.
Cellular Makeup
The human body consists of four essential types of tissue: epithelial, connective, muscle and nervous. Each type is comprised of thousands of cells. Epithelial tissue cells can form into mesothelioma; the other three types cannot.
Epithelial Tissues and Mesothelioma
Each type of tissue cell has its own function for the human body. Epithelial tissue lines the body and its cavities, which includes internal organs like the intestines, lungs and heart.
Cancers comprised of epithelial tissue, such as mesothelioma, are carcinomas. These diseases make up most known cancers.
The epithelial tissue lining the heart, abdomen and lungs is called the mesothelium. This tissue is permeable, meaning it allows liquids and gasses to pass through. The mesothelium is comprised of simple-squamous epithelial cells, also called mesothelial cells.
These cells lubricate the mesothelium and protect nearby body cavities and organs. The wet, permeable construct allows the tissue to bend, which helps the organs expand and contract.
Mesothelial cells also conduct phagocytosis, which is the encapsulation of bacteria, dead cells and foreign particles. This immune response protects the body through the absorption of bacteria or dead cells, which the epithelial cells then expel from the body.
However, when asbestos fibers are absorbed, the result is genetic mutation. This phenomenon occurs because the fibers are sharp and the mesothelial cells cannot expel them effectively. The fibers aggravate the cells, which then mutate and duplicate at an unchecked rate. The duplication forms tumors.
Treatment by Mesothelioma Cell Type
Each histological type of mesothelioma has multiple subtypes, which makes each case unique. However, cell type is not the only factor in a patient’s prognosis and mesothelioma treatment.
Location and stage of disease are most important in determining treatment. Doctors are likely to take cell type into consideration when determining how aggressive treatment should be — as sarcomatoid mesothelioma cells spread rapidly in the body.
If you are a mesothelioma patient, you should prioritize finding a specialist who can diagnose and treat your disease. Your doctor should know of the three cell types and how they differ in microscopic appearance and general prognosis.
Find a mesothelioma specialist who is capable of identifying your cell type, making an accurate diagnosis and forming a treatment plan for your disease. Our free Doctor Match program can connect you with an esteemed specialist.
Frequently Asked Questions About Mesothelioma Cell Types
How many cell types are possible for mesothelioma?
Mesothelioma can be diagnosed from one of three different cell types: epithelioid, sarcomatoid and biphasic. Biphasic is a combination of epithelioid and sarcomatoid cells.
How are the mesothelioma cell types different in appearance?
Epithelioid cells are easier to detect due to their defined shape. They also form in clumps. Sarcomatoid cells have an elongated, stretched-out structure with no clear shape. They’re more difficult to detect during the diagnostic process.
How common is each mesothelioma cell type?
Epithelioid mesothelioma is the most common, occurring in at least 50% of all cases. Sarcomatoid mesothelioma and biphasic mesothelioma make up the remaining cases, with each accounting for 20-30%.
How can you tell the cell type for your mesothelioma?
Histology is the practice doctors use to determine your mesothelioma cell type. Histology is a type of pathology where doctors study the body’s tissue makeup. Cancer specialists examine tissue samples with a microscope and a staining process, which reveals the exact cell type in the tumors.
Sources & Author
- Mesothelioma versus adenocarcinoma. Pathology Outlines. Retrieved from: http://www.pathologyoutlines.com/topic/pleuramesovsadeno.html. Accessed: 04/17/19.
- What is Human Body Tissue. Study.com. Retrieved from: https://study.com/academy/lesson/what-is-human-body-tissue-definition-types-examples.html. Accessed: 04/17/19.
- Carcinoma. Cancer Treatment Centers of America. Retrieved from: https://www.cancercenter.com/carcinoma. Accessed: 04/17/19.
- The mesothelial cell. U.S. National Library of Medicine. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/14592528. Accessed: 04/17/19.
- What Is a Soft Tissue Sarcoma? American Cancer Society. Retrieved from: https://www.cancer.org/cancer/soft-tissue-sarcoma/about/soft-tissue-sarcoma.html. Accessed: 04/17/19.
- 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: 04/17/19.
- Malignant peritoneal mesothelioma: Epidemiology, risk factors, clinical presentation, diagnosis, and staging. UpToDate. Retrieved from: https://www.uptodate.com/contents/malignant-peritoneal-mesothelioma-epidemiology-risk-factors-clinical-presentation-diagnosis-and-staging. Accessed: 12/16/19.
- About Malignant Mesothelioma. American Cancer Society. Retrieved from: https://www.cancer.org/content/dam/CRC/PDF/Public/8733.00.pdf. Accessed: 10/01/19.
- Immunohistochemistry. National Cancer Institute. Retrieved from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/immunohistochemistry. Accessed: 10/04/19.
- Malignant peritoneal mesothelioma: a review. Annals of Translational Medicine. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5497105/. Accessed: 06/10/2020.
