Mesothelioma is a rare and aggressive form of cancer, usually affecting the lining of the lungs or abdomen. The mesothelium is a thin layer of tissue that covers many organs in the body, including the lungs and abdomen. It helps to protect these organs from infection and injury.
Mesothelioma is caused by exposure to asbestos fibers, which irritate the cells of the mesothelium, causing scarring which in turn causes the normal cells to mutate.
There are around 3000 new cases of mesothelioma diagnosed every year in the United States. However, this number is expected to decline since there were restrictions put on the use of asbestos.
There are different types of cells that are present in the body, and they all have their own function. The cells transform into mesothelioma when these cells start to multiply at an abnormal rate.
Just like we have different types of lung and lymphoma, mesothelioma also has different classifications according to its appearance under a microscope. Most cases of mesothelioma are widely classified as either epithelioid, sarcomatoid, or mixed/biphasic, but there are some subtypes that can aid doctors in planning treatments.
Key Facts About Mesothelioma Cell Types
- There are many different types of mesothelioma cells.
- To determine which cell type a person’s mesothelioma is, healthcare providers will look at the cells under a microscope.
- More than half of mesotheliomas are epithelioid.
- About 10% to 20% of mesotheliomas are sarcomatoid.
- The remaining 20% to 30% of mesotheliomas are biphasic.
- The prognosis of mesothelioma is not only dependent on the type and stage of the cancer, but also on the cell type that makes up the cancer.
- Mesotheliomas can be broadly categorized as either benign or malignant types.
- It has been suggested that female patients with mesothelioma have a better life expectancy as compared to male patients, regardless of cell type.
Epithelioid mesothelioma is the form of mesothelioma that most often occurs and accounts for around 75% of cases. This type of mesothelioma grows more slowly than others. It can develop anywhere in the body but is most commonly found on the lining of the lungs, stomach, or other abdominal organs.
- Frequency of occurrence: Epithelioid mesothelioma accounts for more than half of cases of mesothelioma.
- Location: It is most commonly found in the lungs but can be found elsewhere.
- Cell appearance: These cells are clumped together, so it is easy to tell them apart from other types of mesothelioma cells.
- Prognosis: People with epithelioid mesothelioma have a median survival of 18 months.
Treatment for epithelioid mesothelioma typically involves a combination of surgery with other treatments such as chemotherapy. Combining these treatments has been determined to significantly improve outcomes, compared to single-line treatments.
Sarcomatoid mesothelioma is a rare form of cancer typically found in the lungs. The cells can spread to other areas of the body, and this form of cancer does not respond well to treatment. It usually progresses more quickly than epithelioid mesothelioma and has a poorer outcome from treatment.
- Frequency of occurrence: One study found that around 17% of tumors examined were sarcomatoid, in line with the estimated averages of 10-20% of all mesothelioma being sarcomatoid
- Location: This can be found in the lungs but also may develop in the stomach cavity.
- Cell appearance: These cells are oval and spindle-shaped.
- Prognosis: People with sarcomatoid mesothelioma have a median survival of 7 months.
Sarcomatoid mesothelioma is the least common type of mesothelioma when grouped by cell type, but it is the most aggressive. In a 2010 study, the average survival rate was 3.5 months, but as advances in medicine improve, the prognosis does too.
Biphasic mesothelioma is a rare type of mesothelioma, also known as mixed mesothelioma. This type of cancer originates in the pleura, the thin membrane that lines the lungs and chest cavity. Biphasic tumors are also uncommon. Biphasic tumors have parts that are epithelioid, and some that are sarcomatoid.
- Frequency of occurrence: Around 20-30% of all mesotheliomas are recognized as being biphasic.
- Location: Biphasic mesothelioma is often found in the lungs and chest.
- Cell appearance: Cells in a biphasic tumor are a mixture of epithelioid and sarcomatoid cells.
- Prognosis: People with biphasic mesothelioma have a median survival of 10 months.
The prognosis of biphasic mesothelioma depends on the proportion of the tumor made up of each cell type. Tumors with a higher proportion of sarcomatoid cells tend to have a worse prognosis than those primarily made up of epithelioid cells.
Adenomatoid mesothelioma is often misdiagnosed as an adenomatoid tumor. Adenomatoid tumors are typically classified as benign, but mesothelioma is a cancer. Therefore, adenomatoid mesothelioma is cancerous. It is a rare type of mesothelioma that can be mistaken for adenomatoid tumors because it may also produce no symptoms.
- Frequency of occurrence: Studies suggest that adenomatoid mesothelioma accounts for approximately 5% of pleural mesothelioma.
- Location: Usually occurs in the lungs but has been reported to develop in the abdomen.
- Cell appearance: Usually flat or cube-shaped.
- Prognosis: One 2010 study suggested a mean survival of 10 months from the time of diagnosis.
The main presenting symptoms of adenomatoid mesothelioma include cough, shortness of breath, and chest pain, all of which could be mistaken for other conditions.
Benign cystic mesothelioma (BCM) is a very uncommon type of mesothelioma and is caused by asbestos exposure. BCM lesions are rare, with only 130 cases reported since the first case described by Smith and Mennemeyer in 1979.
- Frequency of occurrence: This type of mesothelioma is exceptionally rare. It is often found incidentally when tests are carried out for other reasons.
- Location: Typically occurs in the peritoneum of the abdominal cavity.
- Cell appearance: Smooth, multicystic masses with a thin wall.
- Prognosis: One study found that 80% of participants remained disease free at their 10-year follow-up.
BCM usually develops in women but has been known to occur in men. It has the potential to turn malignant, so most healthcare professionals recommend surgery to remove the tumor. It can recur in the same place.
Desmoplastic mesothelioma is a subtype of sarcomatoid mesothelioma. Desmoplastic mesothelioma is most common in males and typically occurs after the age of 40. However, cases have been observed in patients as young as 12 years of age.
Sometimes, it can be difficult to diagnose desmoplastic mesothelioma as it can look similar to reactive pleural fibrosis.
- Frequency of occurrence: Desmoplastic mesothelioma accounts for around 5–10% of malignant mesotheliomas.
- Location: This mostly occurs in the lungs but can occasionally be present in the heart or stomach regions.
- Cell appearance: Dense bundles of collagen fibers in irregular ‘cartwheel’ patterns.
- Prognosis: According to the US Social Security Program Operations Manual System (POMS), the median survival rate for people with desmoplastic mesothelioma is around six months following diagnosis.
Desmoplastic mesothelioma is a rare kind of cancer that affects the lining of the lungs. It is typically diagnosed in an advanced stage and treatment options are limited. Surgery is rarely an option by the time desmoplastic mesothelioma is diagnosed, due to how advanced it typically is by this point.
The most commonly used treatment includes chemotherapy, radiation therapy, and targeted therapies designed to shrink tumors. Doctors will often recommend palliative care. Fluid buildup can cause a cough and breathing difficulty. Removal of it with a special draining device is needed to reduce discomfort.
Well-Differentiated Papillary Mesothelioma
Well-differentiated papillary mesothelioma (WDPM) is another rare subtype of epithelioid mesothelial tumor that occurs in the peritoneum of people over a wide age range. It is also known as papillary mesothelioma.
Papillary mesothelioma is usually benign, but there have been reported cases of it turning malignant.
- Frequency of occurrence: This is also very rare.
- Location: Well-differentiated papillary mesothelioma most commonly arises in the peritoneal cavity, but can also be found in the pleural cavity, pericardium, and tunica vaginalis.
- Cell appearance: Papillary structures lined by bland-looking, single-layered mesothelial cells.
- Prognosis: Because this is usually benign, it can typically be removed with surgery, and the prognosis is favorable.
One 2019 study found that all but one patient had zero symptoms and that most of the tumors were found incidentally during surgery for other causes.
Small Cell Mesothelioma
Small cell mesothelioma is a subtype of epithelioid mesothelioma that was first identified in 1992. It is so rare that there has been minimal research into it. In fact, researchers suggest that it may even be overlooked in cases where the cells only make up a small proportion of the tumor as a whole.
They are usually found in biphasic tumors, where the tumor is made up of both epithelioid cells and sarcomatoid cells.
- Frequency of occurrence: Small cell mesothelioma is exceptionally rare, especially when the cells appear as part of a tumor mostly made up of other cells.
- Location: Often appears in the lungs.
- Cell appearance: Small cell mesothelioma can be characterized by the appearance of a monotonous arrangement of uniform small cells.
- Prognosis: A small study looked at 6 patients with small cell mesothelioma and found that the mean survival was 8.2 months.
Small cell mesothelioma may often be misdiagnosed as small cell lung carcinoma, as there are many similarities.
When to See a Doctor
It’s important to see a doctor if you have been exposed to asbestos because the symptoms can sometimes be overlooked for a long time. There are many different conditions that can arise, such as lung cancer and mesothelioma.
The symptoms of mesothelioma are not always clear. The disease can remain undetected for years, and the symptoms may be similar to those of other diseases.
See a doctor immediately if you have a cough that lasts longer than two weeks, or if you experience chest pain or shortness of breath.
Frequently Asked Questions
Read on to find out the answers to common questions regarding mesothelioma cell types.
How does a mesothelioma cell type affect my prognosis and treatment?
In the world of cancer, each cell type is important to know. Mesothelioma cells have many different variations, and it affects treatment options. Mesothelioma cells vary in size and shape, which can help doctors decide on the best treatment approach.
What are the 3 types of mesothelioma?
There are 3 main types of mesothelioma: pleural, peritoneal, and pericardial. Pleural mesothelioma is when the tumor starts in the pleura which is a membrane that covers the lungs and lines their inside walls. Peritoneal mesothelioma starts in the lining of the abdomen or around internal organs like the intestines or stomach. Pericardial mesothelioma starts in one of two membranes that surround your heart.
What is the rarest form of mesothelioma?
Testicular mesothelioma is an incredibly rare form of cancer that only affects about 100 cases in research documents. Deciduoid mesothelioma is a rare type of mesothelioma. It has only been diagnosed in a small number of cases, making it very unique.
What triggers mesothelioma?
Mesothelioma is a type of cancer that affects the membrane that covers the lungs and heart, as well as the lining of the abdominal cavity. It is caused by exposure to asbestos fibers, which can be inhaled from dust or fumes.
Mesothelioma occurs when thin layers of cells are removed from these membranes, causing them to become inflamed. This inflammation can cause scar tissue to form and eventually lead to cancerous tumors.
This condition usually happens after several years of exposure to asbestos fibers, but it can also happen after short exposures.
How fast does mesothelioma progress?
Mesothelioma can progress quickly or slowly depending on how much time has passed since exposure to asbestos. The average time for progression is around 12 months, but some patients have died within six months after diagnosis while others have lived for years with their disease before it progressed to a point where they needed treatment.
Where can I get treatment for mesothelioma?
Mesothelioma treatment is available in many places. You should check with your healthcare providers to find out where you can get treatment for this condition. Make sure you choose a specialist in this area for the best possible outcomes.
Mesothelioma is a type of cancer that occurs when asbestos fibers are released into the body. These fibers can cause scarring and lead to the destruction of the lungs, heart, and other organs.
The next steps for someone with mesothelioma will depend on the type of treatment they receive. Some treatments include surgery, chemotherapy, radiation therapy, and immunotherapy. For those who have already undergone treatment, the next steps include monitoring their health and taking care of their symptoms.
If you or a loved one has been diagnosed with mesothelioma or another type of cancer-related to asbestos exposure it is important to know what your options are in terms of treatment and support programs available.