What is Sarcomatoid Mesothelioma?
Upon exposure to asbestos (a group of fibrous chemicals commonly found in building supplies), healthy cells can genetically mutate into mesothelioma cell types. Rather than listening to regulatory signals, these cancerous cells grow and divide in an uncontrolled manner and spread to distant parts of the body.
Sarcomatoid cells are one of the three cell types of mesothelioma and arise from mutations that occur when epithelial cells transform into connective tissue cells—a common biological process called epithelial-to-mesenchymal transition (EMT).
Accounting for around 10% of diagnosed cases, sarcomatoid cells are the rarest form of mesothelioma and the most difficult cell type to treat. Most cases of sarcomatoid mesothelioma are found in the chest cavity. Due to its rarity and similar characteristics with benign tissues and other sarcomas (cancers that are found in connective tissues), sarcomatoid cell type is frequently misdiagnosed.
When correctly identified using multiple screening methods and cellular markers, sarcomatoid cells are large and fibrous-looking, with behaviors that cause them to organize in small lumps opposed to large masses. Sarcomatoid cell type has limited treatment options and is associated with the worst prognosis.
Understanding cell type is an essential part of an overall diagnosis. Each cell type displays different characteristics, subtypes, and growth behaviors, which all have an effect on viable treatment options and overall prognosis of the disease.
In order for doctors to develop a proper treatment plan, they must first understand the structure, function and chemistry of the patient’s mesothelioma cell type. Understanding these variables gives doctors more information on how these cells will interact with body systems and how fast they are likely to spread to surrounding tissues and structures. It also gives them more supporting data to make an accurate diagnosis.
Sarcomatoid cell type is diagnosed when a biopsy, or tumor sample, is collected and certain physical characteristics and behaviors are viewed by a pathologist doctor under a microscope. Sarcomatoid mesothelioma is the hardest cell type to diagnose due to their similarities with healthy cells, benign tissues and other cancer types.
Sarcomatoid cell type is frequently misdiagnosed as sarcomatoid carcinoma, cancers found in tissues that line internal organs, cancer in connective tissues, as well as various forms of cancer that occur in the cartilage, muscle and blood vessels near the leg, arm and neck joints. It can also be misdiagnosed as fibrous pleurisy—a benign (non-cancerous) condition.
Apart from observing cell behaviors and characteristics, doctors can work with specialists to ensure a proper diagnosis is made and the patient is put on the correct treatment plan. Pathologist specialists are able to apply various stains to tumor samples. These stains contain specialized markers or proteins that attach to certain cells. Markers make it easier to see cells under a microscope and help to differentiate mesothelioma cell type and overall cancer diagnoses.
The different behaviors that epithelioid, sarcomatoid and biphasic cells types display have a major impact on the rate at which these cells replicate and spread. Cell type replication and mobility have a direct correlation with a patient’s prognosis—their survival rate and life expectancy.
A trait unique to sarcomatoid cell type is their rare occurrence in large masses or lumps, which is a common behavior in the other two cell types. Sarcomatoid cells will usually be scattered on the linings of cavities or organs as small disorganized bumps or nodules. This organization allows sarcomatoid cells to spread quickly throughout the body. As these nodules grow, they can combine to create sheets of sarcomatoid cells. This sporadic and quick growth behavior has a poor effect on a patient’s prognosis.
Cellular characteristics including shape, size, and internal structure variations can be key pieces of information when doctors are performing a diagnosis. Biopsy samples are viewed under a microscope and cell characteristic observations are made to further differentiate the sample from other tissues.
Sarcomatoid mesothelioma contains large cells that take on spindled and irregular shapes. These cells can sometimes be viewed as fibrous-looking groups with more than one nucleus, the molecular structure that holds the cells DNA. These characteristics are consistent with most sarcomatoid cells, however, there are numerous subtypes that display varying physical features.
Variables such as cell type, tumor location, and disease stage will help to determine which treatment options are offered to patients. Along with these factors, a patient’s age, previous responses to illnesses and medical treatment, along with their overall health will also be considered. Generally, mesothelioma has the best prognosis when treated with a multimodal approach of surgery, chemotherapy and radiation therapy. Unfortunately, the aggressive and irregular behavioral of sarcomatoid cell type makes treatment very difficult.
Sarcomatoid cells are the hardest form of mesothelioma to treat because the cell type does not generally grow as one single tumor mass and is able to spread throughout the body at a rapid rate. Depending on the case, doctors may suggest one of the three standard mesothelioma treatments or a combination of them.
The success of radiation therapy depends on a medical professional’s abilities to isolate cancerous cells from healthy tissues. When treating sarcomatoid mesothelioma with radiation it is hard to hit the small groups of cells with particles or waves that are used to disrupt the cell’s replication mechanisms.
Surgery is sometimes used to treat sarcomatoid mesothelioma. However, it is challenging to remove all of the cancerous cells, as sarcomatoid cell type is generally dispersed throughout the body in small nodules.
The third option used to treat sarcomatoid mesothelioma is chemotherapy—a type of drug that damages cells and prevents them from duplicating and moving to other parts of the body. Doctors have had some success in treating sarcomatoid mesothelioma with chemotherapy, especially when multiple chemotherapy agents are used. Multiple rounds of chemotherapy may be required to adequately shrink or remove sarcomatoid tumors.
As new cases of sarcomatoid mesothelioma are diagnosed, scientists hope that further research will inform better treatment options and procedures that will contribute to a better prognosis for the disease.
As its growth is sporadic and mobility is rapid, sarcomatoid mesothelioma has the least favorable prognosis in comparison to the other two cell types.
The average survival time of patients with sarcomatoid cell type is around 6 months following diagnosis. Studies have found variations in survival rates from 3.5 months, 5.8 months and 6.2 months, with some patients living 5+ years after their diagnosis.
Sarcomatoid mesothelioma prognosis varies heavily on location, disease stage and how far the cancerous cells have spread. The majority of sarcomatoid tumors are found in the pleura or chest cavity, with few cases found in the peritoneum or abdominal lining. In general, the prognosis of sarcomatoid mesothelioma is worse than epithelioid and biphasic cell types, but variants such as a patient age, overall health, diet and lifestyle habits can create varying life expectancy and survival rates.
Sarcomatoid Cell Subtypes
When viewing a sarcomatoid tumor sample it is possible to identify more than one subtype as well as traces of epithelioid cells—another cell type of mesothelioma. Identifying cell subtypes is an important part of a patient’s overall diagnosis, as recent studies have found that subtype characteristics can have a large impact on disease prognosis.
Sarcomatoid mesothelioma can be classified into the following subtypes:
- Desmoplastic: Desmoplastic subtype describes spindle shaped cells that exhibit dense fibrosis (fibrous connective tissue or scarring) and present themselves in a disorganized orientation. Desmoplastic cells are one of the most common sarcomatoid subtypes.
- Osteosarcomatous and Chondrosarcomatous: Osteosarcomatous and chondrosarcomatous cells are found in bone and cartilage within membranes that line the chest, heart and abdominal cavities.
- Lymphohistiocytoid: Lymphohistiocytoid sarcomatoid cells are typically found bundled in the lymphatic system which causes them to be commonly misdiagnosed with other cancers of the immune system. This subtype has the best prognosis among all cases of sarcomatoid mesothelioma. It is somewhat controversial whether lymphohistiocytoid subtype could be categorized as sarcomatoid or epithelioid as epithelioid cells are commonly found in tumor bundles.
If you’ve received a mesothelioma diagnosis, it’s important to seek a second opinion. Mesothelioma is extremely complex, and with such a variety of possible cell types, it can be easy to misdiagnose. For more information on seeking a second opinion on your diagnosis, contact our Victim Advocates today.