Sarcomatoid Mesothelioma

Mesothelioma is a rare and lethal cancer affecting the thin layer of tissue surrounding the internal organs. The World Health Organization classifies malignant mesothelioma into three types, based on cell structure and type:

  • Epithelial
  • Biphasic
  • Sarcomatoid

The rarest form of the disease is sarcomatoid mesothelioma, and it affects from 10% to 20% of all patients.

Prognosis and Life Expectancy

Sarcomatoid mesothelioma isn’t just the rarest form of the disease; it’s also the most aggressive of the three types of mesothelioma, with the least favorable prognosis. Some research indicates patients live around 6 months after diagnosis.

In one study, only 30% of patients lived past 6 months; after a year, only 10% remained alive. On the other hand, the survival rate for epithelioid mesothelioma tends to run from 12 to 24 months.

Characteristics of Sarcomatoid Mesothelioma

Sarcomatoid mesothelioma is one of three subtypes of histological mesothelioma. Histopathology, the study of tissue and the changing characteristic of diseased cells, is instrumental in diagnosing various types of cancer, including mesothelioma.

There are several variants of sarcomatoid mesothelioma, most notably the desmoplastic and lymphohistiocytoid subtypes.

Sarcomatoid cells are named for their resemblance to the cells of a sarcoma, or a cancer that grows from connective tissue cells. The cells of sarcomatoid mesothelioma tend to be elongated and spindle-shaped and overlap each other. This means they resemble different soft tissue tumors, which can make it difficult to form a precise diagnosis. In turn, that can impede the rapid treatment of the disease.

Symptoms of Sarcomatoid Mesothelioma

The symptoms include the following:

  • Chest pains
  • Trouble breathing
  • Pleural effusion—fluid buildup
  • Pain when coughing
  • The appearance of subcutaneous lumps on the chest
  • Unexplained weight loss

Once an individual is exposed to asbestos, though, it can take anywhere from 20 to 50 years for symptoms of mesothelioma to finally appear.

Diagnosing the Disease

Diagnosis of mesothelioma can be performed a number of ways. An asbestos exposure history, if known, is considered diagnostically useful. Saliva and lung biopsy samples can be examined for a higher than normal concentration of asbestos fibers. Pleural effusion, which is the liquid that can form around diseased lungs, can be examined for signs of malignancy. A more invasive but highly accurate method is called thoracoscopy, which involves taking biopsy samples from the pleural cavity using an endoscope and then performing a number of definitive histological procedures on the sample. Other diagnostic assays may also be employed.

Since the cells tend to mirror those of other diseases such as pulmonary sarcomatoid carcinoma, immunohistochemistry data is imperative to distinguish sarcomatoid mesothelioma from other spindle-type cells and diseases. Sarcomatoid mesothelioma cells are keratin-positive, meaning that they will react to some antikeratin antibodies used during the staining of cell samples.

Treating the Disease

Treatment for sarcomatoid mesothelioma is similar to that of other forms of the disease. It consists of a combination of chemotherapy, surgery, and radiation. Since a diagnosis of mesothelioma typically occurs at Stage 3 or later, the goal of treatment is usually focused on prolonging patient survival and improving quality of life.

The incidence rate for mesothelioma in the U.S. was about 0.97 per 100,000 between 1973 and 1999. Between 2,000 and 3,000 new cases are reported each year.