Biphasic Mesothelioma: An Overview of Inadequately Diagnosed Mesothelioma

Biphasic mesothelioma is a term used to describe mesothelioma cancer that contains two distinct types of malignant cancer cells: epithelioid mesothelioma cells and sarcomatoid mesothelioma cells. The most common cells to occur with mesothelioma are epithelioid cells, which are easily confused for adenocarcinoma or another disease. However, biphasic mesothelioma which presents both cells types cannot be confused for common diseases. Sarcomatoid cells only appear in about 15% of mesothelioma cases and their presence in an epithelial structure such as the mesothelium is rare, but seems to be growing in a number of cases.

Biphasic mesothelioma diagnosis requires that several samples, each from a different part of the same tumor, are carefully examined under a microscope. A mixture of the two cells types is indicative of the mesothelioma subtype. The basic treatment for each type of mesothelioma is the same but there are some differences between epithelioid, sarcomatoid, and biphasic mesothelioma prognoses. Additionally, some new types of treatments target specific types of cells, so biphasic mesothelioma may be best treated with a specialty therapy. Prognosis (the patient’s outlook regarding the cancer) can vary between individuals and can change based on which type of cell seems to be the dominant malignancy in the mesothelium.

The Composition of Biphasic Mesothelioma

As mentioned in the introduction, biphasic mesothelioma is a subtype that includes both of the types of cells that occur in those with one of the four types of mesothelioma: pleural, peritoneal, pericardial, and tunica vaginalis. The two cell types are epithelioid and sarcomatoid.

• Epithelioid mesothelioma cells are cube shaped cells with a clear nucleus. Epithelioid tumors are comprised of these types of cells and are the most common cells to occur with mesothelioma; occurring in 50-70% of mesothelioma cases. They are contain small flanges within the cell membrane.
• Sarcomatoid mesothelioma cells are elongated, almost spindle shaped with no clear nucleus. Sarcomatoid cells have no clear organization when grouped together.

Together, these two cells’ presence in a single tumor makes up “biphasic mesothelioma”. More often than not, they are present in separate parts of the tumor. They don’t usually “mix” with each other. Therefore, a biopsy that takes samples from different parts of the tumor is required for accurate examination of the tumor. For this reason, many doctors stopped using the most non-invasive form of biopsy for mesothelioma cancers. The needle biopsy method requires no surgery, but only extracts a very small sample from one portion of the tumor. In cases where a needle biopsy is still used, diagnosing biphasic mesothelioma requires multiple needle biopsies; each extracting a sample from a different part of the tumor. The diagnostic process must be more ardent in discovering biphasic mesothelioma so that it can be properly treated.

Prognosis is only altered by a few months in most cases. The average mesothelioma diagnosis will carry a prognosis of less than one year. Biphasic mesothelioma prognosis is similar.

Biphasic Mesothelioma Symptoms Aren’t Usually Helpful in Diagnosis

Symptoms are typically unaffected by the cell type, as all symptoms of mesothelioma more often relate to the tumor’s size and not the composition. Location is also an important factor in determining the cause of symptoms. Biphasic mesothelioma, like all cancers, may cause a person to feel tired, have a fever, or experience unexplained weight loss. Beyond the general symptoms, however, biphasic mesothelioma will cause symptoms like pain, nausea, vomiting, or difficulty breathing. The specific symptoms greatly depend on the location so the typical symptoms of the primary mesothelioma type will prevail.

Pleural mesothelioma symptoms with biphasic cell types in the chest cavity may cause chest pain, dry or painful cough, difficulty swallowing, back pain, hoarseness, swelling in the upper extremities, breathlessness, and difficulty swallowing.

Peritoneal mesothelioma symptoms with biphasic cell types in the abdominal cavity may cause abdominal pain, abdominal swelling, weight loss, digestion issues, and loss of appetite or superficial lumps due to tumors just beneath the skin.

Pericardial mesothelioma symptoms with biphasic cell types on or near the hear may cause irregular heartbeat, chest pain, heart arrhythmia, weakness and fatigue, fever and chills or sweating, difficulty breathing, or shortness of breath that’s worse when lying down.

These symptoms are all very common to myriad conditions, so symptoms alone cannot determine that an individual has a specific disease. Biphasic mesothelioma is often undetected until surgery to alleviate one of the symptoms occurs. During surgery, it is common for doctors to remove several samples of abnormal tissues. This is typically when biphasic mesothelioma is discovered.

Biphasic Mesothelioma Treatments

As mentioned, treatment doesn’t vary much between cell types and is more focused on the stage and location of mesothelioma. Biphasic mesothelioma treatments might include any of the following treatments or a combination of them. Treatments are broken down into two categories, curative and complementary.

In addition to curative treatments such as those in the table above, complementary treatments may assist in alleviating the symptoms of biphasic mesothelioma.