* Malignant Biphasic Mesothelioma
Biphasic mesothelioma is one of the three main histologic subtypes of malignant mesothelioma. Approximately 20 to 35 percent of all malignant mesothelioma cases are classified as biphasic mesothelioma, making the biphasic subtype the second most common histologic form of the disease.
Characteristics of Biphasic Mesothelioma
Biphasic mesothelioma is made up of cells from both of the two other histologic categories of malignant mesothelioma, which include:
- Epithelial mesothelioma – Epithelial mesothelioma is commonly comprised of round, cuboidal or polygonal cells that have long and slender microvilli, which are small hair-like protrusions in the cell membrane.
- Sarcomatoid mesothelioma – Sarcomatoid mesothelioma is typically made up of spindle cells arranged in a disorganized fashion.
In biphasic mesothelioma, epithelial cells and sarcomatoid cells can exist in close proximity or, more frequently, within distinctly separate areas of a tumor. Biphasic mesothelioma is more common in pleural mesothelioma than peritoneal mesothelioma.
How Biphasic Mesothelioma is Diagnosed
While the World Health Organization recommends that biphasic mesothelioma only be diagnosed when a tumor contains at least 10 percent of epithelial cells and 10 percent of sarcomatoid cells, a general consensus on this criteria has not been established in the medical community.
In order to diagnose biphasic mesothelioma, other types of cancer that can display biphasic characteristics, such as synovial sarcomas and carcinosarcomas, must be ruled out. Techniques such as immunohistochemistry, which identifies and labels certain proteins in cells, can be used to distinguish biphasic mesothelioma from these other diseases.
Because of the small cell samples typically used during diagnostic testing, and the fact that epithelial cells and sarcomatoid cells can exist in different areas of a tumor, biphasic mesothelioma is often difficult to detect and diagnose. A correct diagnosis of biphasic mesothelioma is more likely to occur after the evaluation of a substantial amount of tissue, such as the sizeable sample obtained during a surgical biopsy, rather than after the assessment of smaller samples obtained during radiological-guided biopsies.
A recent study published in the Journal of Thoracic Oncology found that, out of 83 patients confirmed to have biphasic pleural mesothelioma after undergoing an extensive surgical procedure called an extrapleural pneumonectomy, only 26 percent had been originally diagnosed with the biphasic subtype during an initial diagnostic biopsy process that relied upon the use of thoracoscopy, thoracotomy, computerized tomography or other methods.
While biphasic mesothelioma remains difficult to diagnosis, recent advances and developments in diagnostic testing have increased the percentage of mesothelioma cases classified under the biphasic subtype.
How Biphasic Cells Affect Treatment and Prognosis
The prognosis for patients with biphasic mesothelioma can vary, depending upon the specific mix and ratio of epithelial cells and sarcomatoid cells present in each individual case. Because sarcomatoid mesothelioma is typically less responsive to treatment than epithelial mesothelioma, biphasic patients with lower levels of sarcomatoid cells tend to respond better to treatment.
While there is no cure for biphasic mesothelioma, a number of different treatment optionsmay be available, depending upon the severity and location of the cancer.
Want Another Opinion?
Mesothelioma patients are urged to get other opinions from specialized physicians about their disease. The Mesothelioma Center's Doctor Match Program excels at putting patients together with top doctors. Call (800) 549-0544 for more information.
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