* Malignant Sarcomatoid Mesothelioma

    When diagnosing malignant mesothelioma, a doctor will perform a tissue biopsy to determine which cell types are found in cancerous tissue. Sarcomatoid mesothelioma cells are one cell type that may be discovered when a tissue sample is examined under a microscope. Identifying the type of mesothelioma cells involved with a particular tumor can help to determine which treatment plan a patient will follow.

    Unfortunately, sarcomatoid mesothelioma cells are known to be particularly resistant totreatment, which may mean that the typical combination of surgery, radiation and chemotherapy is not as successful.

Characteristics of Sarcomatoid Mesothelioma

    Sarcomatoid mesothelioma is one of the three main subtypes of malignant mesothelioma. Approximately 15 to 20 percent of malignant mesothelioma cases are diagnosed as sarcomatoid, a term which describes the appearance of malignant mesothelioma cells under a microscope and categorizes them according to their cellular form and structure.

    Sarcomatoid cells are named for their structural resemblance to the cells of a sarcoma, or a cancer that arises from connective tissue cells. Malignant mesothelioma cells described as "sarcomatoid" are generally elongated and spindle-shaped when viewed under a microscope.

    The irregularly-shaped sarcomatoid cells often overlap in a fibrous, haphazard pattern. Sarcomatoid mesotheliomas are often difficult to diagnose in that they tend to resemble fibrosarcomas, or malignant, soft tissue tumors derived from fibrous connective tissue (notmesothelioma tissue).

How Sarcomatoid Mesothelioma is Diagnosed

    To diagnose mesothelioma cells as sarcomatoid, a histological examination of tumor tissue is performed. Sarcomatoid cells often will look very similar to other types of sarcomatoid cells, such as those of sarcomatoid carcinomas, or tumors which affect the epithelial cells of the body. Sarcomatoid mesothelioma is commonly misdiagnosed as pulmonary sarcomatoid carcinoma, a cancer which affects the lungs and produces symptoms almost identical to mesothelioma.

    To that extent, immunohistochemistry data is essential in distinguishing sarcomatoid mesothelioma cells from sarcomatoid carcinomas and other spindle-type cells. The cells of sarcomatoid malignant mesothelioma are keratin-positive, meaning that the cells will react with certain antikeratin antibodies used during the staining process of cell samples.

Desmoplastic Mesothelioma

    Even more difficult to diagnose than sarcomatoid mesothelioma, desmoplastic mesothelioma is considered a variant of the sarcomatoid subtype and is also often misdiagnosed as benign (non-cancerous) fibrous tissue. Desmoplastic mesothelioma is a rare variant, making up only 5 to 10 percent of all cases of malignant mesotheliomas.

How Sarcomatoid Cells Affect Treatment & Prognosis

    While sarcomatoid mesotheliomas are the least common form of malignant mesothelioma, the subtype is unfortunately considered the most deadly due to its aggressive nature. Sarcomatoid mesothelioma cells are treated with the same therapies as the other subtypes, but sarcomatoid cells are more resistant to treatment than epithelial or biphasic subtypes.

Cases of sarcomatoid mesothelioma are often especially resistant to chemotherapy. This response to treatment leads to a poorer prognosis for patients diagnosed with this subtype, as well as a reduced survival time.

Talk to a Patient Advocate

    Do you want to talk to someone about your disease? We'll listen. Call one of the Mesothelioma Center's Patient Advocates at (800) 615-2270.

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