Malignant Sarcomatoid Mesothelioma
May 14, 2009 by Jack
What’s Malignant Sarcomatoid Mesothelioma?
In histological terms, there are four different types of mesothelioma: sarcomatoid, epithelial, biphasic, and desmoplastic (a variant of sarcomatoid). Please see Epithelial and Biphasic for information on these other types of malignant mesothelioma cells. In clinical medicine, the term histopathology refers to the microscopic examination of cellular tissue to gain insight into the manifestations of various diseases.
Malignant sarcomatoid mesothelioma is the least common of the three cellular mesothelioma types. This form of mesothelioma accounts for approximately 7 to 20 percent of cases. When viewed under a microscope, malignant sarcomatoid mesothelioma cells appear as elongated spindle-shaped cells that are irregularly shaped and often overlap one another.
Desoplastic mesothelioma is considered a variant of sarcomatoid mesothelioma. This form is likely the most difficult of all mesotheliomas to diagnose. When desoplastic mesothelioma invades or metastasizes, the cells can appear very bland and can be misdiagnosed as benign fibrous tissue. Medical experts in mesothelioma say this form of mesothelioma should not be diagnosed with a needle core biopsy.
It’s important to know that malignant sarcomatoid mesothelioma is sometimes difficult to diagnose on the basis of histological methods. For example, cells of another type of cancer called pulmonary sarcomatoid carcinoma are very similar in appearance (as well as other characteristics) to malignant sarcomatoid mesothelioma.
Types of Malignant Mesothelioma
Epithelioid Mesothelioma
Of the three types of malignant mesothelioma, epithelioid is the most common, occurring in approximately 50 to 70 percent of cases. These mesothelioma cells have been given this name because they have the appearance of epithelial cells, which line organs and cavities throughout the human body. Epithelioid mesothelioma cells generally feature a well-defined, uniform shape when viewed under a microscope.
Biphasic Mesothelioma
The second most common type of mesothelioma is called biphasic mesothelioma. Accounting for roughly 20 to 40 percent of all mesothelioma cases, biphasic mesothelioma tumors are composed of both epithelioid and sarcomatoid cells. Instead of appearing as an even mixture of cells, these cells are usually arranged in groups within a tumor. Because of this factor, several samples are taken from different locations within a tumor during the biopsy, which is done to ensure a correct diagnosis is made.
In most cases, those diagnosed with biphasic mesothelioma are considered to have a bleaker prognosis than patients diagnosed with epithelioid or sarcomatoid mesothelioma. Since biphasic tumors are generally more treatment-resistant, this form of malignant mesothelioma often receives more aggressive treatment than other forms of mesothelioma.
Sarcomatoid Mesothelioma
Sarcomatoid mesothelioma is the least common of the three types of malignant mesothelioma, accounting for roughly 10 to 15 percent of diagnosed cases. Visible only when viewed under a microscope, sarcomatoid cells appear as elongated spindle-shaped cells, which feature an irregular shape and often overlap one another.
This form of mesothelioma can be hard to diagnose because it resembles another form of cancer. Cells affected by pulmonary sarcomatoid carcinoma are very similar in appearance and feature other characteristics that are indicative of malignant sarcomatoid mesothelioma as well.
