Key Takeaways
- There are three mesothelioma cell types — epithelioid, sarcomatoid, and biphasic — and identifying which type is present directly affects diagnosis, treatment options, and prognosis.
- Epithelioid is the most common, making up roughly 80% of diagnoses. The cells are rectangular, grow in defined patterns, and respond best to treatment — including surgery, chemotherapy, radiation, and targeted therapy.
- Sarcomatoid is the rarest (7–15% of diagnoses) and most aggressive. The spindle-shaped cells spread rapidly to other parts of the body, making surgery difficult and limiting treatment options to chemotherapy, immunotherapy, and radiation.
- Biphasic contains both epithelioid and sarcomatoid cells (10–20% of diagnoses). Treatment effectiveness depends on which cell type is dominant — and biphasic is often underdiagnosed compared to epithelioid.
- Understanding the cell type — not just the location of the cancer — is essential for developing the most effective treatment plan.
Investigating not only the location of the mesothelioma but the type of cell initiated can reveal how to best approach treatment. There are three main cell types concerning mesothelioma: epithelioid, biphasic, and sarcomatoid (“Types and Grades of Mesothelioma”). Mesothelioma is a rare form of cancer that lines the mesothelial tissue. This type of cancer most commonly occurs in the lungs and abdomen but can additionally occur in the heart and testicles. Each cell type will be further described below.
Epithelioid
Epithelioid is the most common type of mesothelioma. Epithelioid sarcoma is a “type of cancer that starts as a growth of cells in the soft tissue” (“Epithelioid Sarcoma – Overview – Mayo Clinic”). Epithelioid cells are often rectangular and are different from sarcomatoid (“Sarcomatoid Mesothelioma, Symptoms & Treatment”). Due to the range of possibilities where this cancer can grow, the lungs, abdomen, heart, and testicles are all vulnerable to exposure. This makes up roughly “80% of patients” diagnosed with mesothelioma(Luka Brcic and Kern). While this number is vast there are multiple treatment options to minimize the effects and possibly even remove it. The treatments include surgery, radiation therapy, targeted therapy, and most commonly chemotherapy(“Epithelioid Sarcoma – Overview – Mayo Clinic”). It is recognized that the symptoms attached to this type of cell concerning mesothelioma can “mimic those of less severe respiratory conditions, such as asthma and pneumonia” (“Types of Mesothelioma”), but can include:
Sarcomatoid
Sarcomatoid tumors are a “type of cancer that looks like a mixture of carcinoma…and sarcoma”(“NCI Dictionary of Cancer Terms”). This is a fuse of cancer that begins in places like the bones and muscles as well as the skin and tissue. Additionally, out of the three different types of cells are the rarest and they are shaped like spindles which in hand impacts their abilities to conjoin. This incompatibility provides an easy way for the spindles to diffuse into other parts of the body (“Sarcomatoid Mesothelioma, Symptoms & Treatment”). The rapid spread further limits the treatment versatility and almost eliminates surgery but still embraces chemotherapy, immunotherapy, radiation therapy, and targeted therapy. It is recognized that most sarcomatoid mesothelioma diagnoses occur in the pleura (“Sarcomatoid Mesothelioma, Symptoms & Treatment”). This can lead to symptoms like:
Additionally, sarcomatoid mesothelioma makes up roughly “7% to 15%” of all mesothelioma diagnoses (“Mesothelioma – Introduction”).
Biphasic
Biphasic tumors are a combination of “different proportions of both spindle cells and epithelioid cells” (Liang et al.). Unfortunately, while this only makes up “10%-20% “of all diagnoses, the treatment options are often limited (“Mesothelioma – Introduction”). Given biphasic is a blend of both epithelioid(responds well to treatment) and sarcomatoid (responds poorly to treatment) it is believed that it impacts the treatment efficiency. It is additionally difficult to diagnose biphasic mesothelioma and the National Library of Medicine even claims that they are undiagnosed compared to epithelioid mesothelioma, which is over diagnosed (Luka Brcic and Kern). This difficulty arises in the “spindle cell component” and whether it is relentless or malignant (Luka Brcic and Kern). The Moffitt Cancer Center believes that the prognosis for the mesothelioma and treatment options will “depend on which mesothelioma cell type is dominant”.
Investigating both the location of the mesothelioma and cell type can help in selecting the best type of treatment. If you or someone you know has been affected by asbestos exposure or mesothelioma in the state of Pennsylvania, please fill out this form for a free consultation or call 1 (800) 505-6000 for legal help.
Frequently Asked Questions
What are the three mesothelioma cell types?
Mesothelioma tumors are classified into three cell types based on how the cancer cells look and behave:
- Epithelioid — the most common (~80% of cases), with rectangular cells that grow in defined patterns and respond best to treatment
- Sarcomatoid — the rarest and most aggressive (7–15%), with spindle-shaped cells that spread rapidly and are hardest to treat
- Biphasic — a combination of both cell types (10–20%), with prognosis depending on which type is dominant
Why does cell type matter for mesothelioma treatment?
The cell type directly affects how the cancer behaves, which treatments are most effective, and the patient’s expected prognosis. Epithelioid mesothelioma responds well to surgery and chemotherapy. Sarcomatoid mesothelioma spreads too quickly for surgery to be effective in most cases. Biphasic outcomes depend on which cell type makes up the majority of the tumor. Without identifying the cell type through biopsy, doctors cannot select the most appropriate treatment approach.
What is epithelioid mesothelioma?
Epithelioid mesothelioma is the most common and most treatable cell type, accounting for approximately 80% of all diagnoses. The cells are rectangular in shape, grow in recognizable patterns, and tend to stay grouped together rather than spreading rapidly. Treatment options include surgery, chemotherapy, radiation therapy, and targeted therapy. Symptoms can mimic less severe respiratory conditions like asthma and pneumonia, which can delay diagnosis.
What is sarcomatoid mesothelioma?
Sarcomatoid mesothelioma is the rarest and most aggressive cell type, making up 7–15% of diagnoses. The cells are spindle-shaped, which makes them unable to bind together tightly — allowing them to spread rapidly to other parts of the body. This rapid spread severely limits treatment options and almost eliminates surgery as a viable approach. Most sarcomatoid mesothelioma occurs in the pleura (lung lining). Symptoms can include coughing blood, persistent cough, and hoarseness.
What is biphasic mesothelioma?
Biphasic mesothelioma contains both epithelioid and sarcomatoid cells in varying proportions, accounting for 10–20% of diagnoses. Treatment effectiveness depends on which cell type is dominant — a tumor with more epithelioid cells will generally respond better to treatment than one dominated by sarcomatoid cells. Biphasic mesothelioma is also particularly difficult to diagnose and may be underdiagnosed compared to epithelioid mesothelioma.
How is the cell type determined?
The cell type can only be definitively identified through a tissue biopsy — a procedure in which a sample of the tumor is extracted and examined under a microscope by a pathologist. Imaging tests alone cannot distinguish between cell types. Accurate cell type identification requires specialized pathology expertise, as sarcomatoid and biphasic presentations can be misclassified without careful analysis.
What should I do if I’ve been diagnosed with mesothelioma?
If you or a loved one has been diagnosed with mesothelioma, understanding your cell type is a critical part of developing the right treatment plan. Ask your oncologist about your biopsy results and which cell type was identified. For information about your legal options, call (800) 505-6000 or fill out our contact form for a free consultation.
