Of all mesothelioma cases diagnosed, sarcomatoid mesothelioma is the least common but most aggressive. Also known as sarcomatous, this type accounts for about 7% to 20% of all cases diagnosed. The lining of the lungs (pleural mesothelioma) and abdomen (peritoneal mesothelioma) are usually affected.
In fact, a study has found that 98% of people suffering from sarcomatoid mesothelioma had tumors affecting the pleura. The peritoneum was affected in only 2% of cases1. In the same study, no incidents were found to affect the lining of the heart (pericardial) or testicles (testicular). Cancerous tissue is made up mainly of sarcomatoid cells. These cells are spindle-shaped, organized in no definite order, and often overlap each other. They also have large nuclei.
Sarcomatoid mesothelioma risk factors
Sub-types of sarcomatoid mesothelioma
The appearance and behavior of the sarcomatous cells define which sub-type of the disease a patient has.
- Conventional: The most common.
- Lymphohitiocytoid: The least common.
- Desmoplastic: The second most common, this type can be confused with benign fibrous pleuritis.
- Osteosarcomatous and/or chondrosarcomatous
Diagnosing sarcomatoid mesothelioma
Your doctor may use imaging scans, radiology, pathology, immunohistochemistry and a physical examination to diagnose you. A biopsy of fluid taken from the affected area is considered ineffective, since sarcomatous cells do not usually shed into the fluid. Misdiagnosis is common, as sarcomatoid mesothelioma can be easily confused with soft tissue tumors. Research has found that immunohistochemistry may be the most effective in making a proper diagnosis, with the use of cytokeratin as a marker2.
Once diagnosed, patients have an average lifespan of about 3.5 months. After that time, life expectancy drops dramatically, with about 10% of patients expected to survive for a year.
The least favorable survival rate
Unfortunately, sarcomatoid mesothelioma has been found to have the worst survival rate than other types of this cancer. This may be for three reasons:
- It spreads faster, affecting secondary tissues such as the muscles, cartilage, bone and fat. Tumors can develop in other areas of the body, far from the point of origin. This is because they don’t stick together as much as mutated epithelial cells.
- Although sarcomatous cells have a distinct appearance, they can be harder to differentiate from healthy tissue or the affected tissue caused by other medical conditions.
- The spread of cancerous tissue makes surgery dangerous for many patients and ineffective as a treatment option.