Biphasic Mesothelioma Diagnosis

How is Biphasic Mesothelioma Diagnosed?

A medical diagnosis is confirmation of a disease or other condition that explains a person’s symptoms. The process of receiving a mesothelioma diagnosis – regardless of whether it’s biphasic mesothelioma or another cell type – involves imaging tests and eventually a biopsy to test tissue samples for the presence of cancerous cells.

Imagining tests may include X-rays, CT scans or MRIs. If the imaging tests detect a mass, doctors will perform a biopsy and extract a sample of tissue from the chest or abdominal cavity – wherever the mass was found – and send it to a laboratory to be examined under a microscope. Specialists examine the biopsy tissue sample under a microscope to determine which cell type is present.

There are three mesothelioma cell types: epithelioid; sarcomatoid; and biphasic. Biphasic mesothelioma is not an actual cell but rather a combination of epithelioid cells and sarcomatoid cells. Biphasic mesothelioma is diagnosed in approximately 20%-30% of all mesothelioma cases.

How to Determine the Cell Type of Mesothelioma

Doctors determine the mesothelioma cell type by studying tissue samples under a microscope. This process is called pathology, which is the microscopic study of tissue or fluid samples for the presence of cancer.

These tests are conducted by pathologists, who examine the appearance of cells. Pathologists identify the cell type based on:

• Behavior
• Size and shape
• Nuclei
• Pattern of the sample

Staining for Biphasic Mesothelioma

Pathologists conduct tests on tissue samples by staining tissue cells, which is a process called immunohistochemistry.

The pathologists stain the tissue cells to see if specific cancer proteins react to indicate the presence of mesothelioma. Epithelioid cells and sarcomatoid cells can have different proteins, so this staining process is a method of determining the cell type.

Biphasic mesothelioma is not an individual type of cancer cell but rather a combination of two types of mesothelioma cancer cells: epithelioid cells and sarcomatoid cells. Therefore, there is no one specific stain for biphasic mesothelioma.

Staining for this biphasic cell type involves getting positive reactions for antigens (markers) on the surface of epithelioid cells and sarcomatoid cells.

Doctors can also look at the appearance of the cells as an identifier for whether they are epithelioid cells or sarcomatoid cells. The two cell types differ in their appearance:

• Epithelioid cells have a well-defined shape and easily visible nuclei. The cells seem to clump together, making them easier to identify.
• Sarcomatoid cells have a long, narrow and oval shape. The cells either have no clearly defined nuclei or multiple elongated nuclei. Sarcomatoid cells do not clump together, often spreading in a disconnected manner.

Steps of a Biphasic Mesothelioma Diagnosis

Regardless of the mesothelioma cell type, there is a specific process patients should follow to receive an accurate diagnosis. The steps are below:

Stages of Biphasic Mesothelioma

After receiving a biphasic mesothelioma diagnosis, patients will learn from their doctor which stage their cancer is in at that time. Most types of cancer have four stages: stage 1, stage 2, stage 3 and stage 4. Doctors determine the stage of mesothelioma by testing the size of the tumors and how far the disease has spread.

The stage of mesothelioma changes and progresses. For instance, a patient in stage 1 or 2 at the time of their diagnosis can advance to stage 3 or stage 4 quickly. The progression of the cancer heavily depends on where the cancer forms and the majority cell type.

The 4 Stages of Biphasic Pleural Mesothelioma

There are four stages of pleural mesothelioma (regardless of the cell type):

• Stage 1 – The earliest stage is defined by tumors localized to the pleura, which is the thin lining of the lungs and where pleural mesothelioma originally forms.
• Stage 2 – This stage is characterized by tumors in the pleura on one side of the chest with possible disease found in the diaphragm or lung tissue on the same side.
• Stage 3 – This is the first advanced stage, with tumors spreading beyond the pleura and to the nearby lung, the chest wall, the diaphragm and the mediastinum (the space between your lungs).
• Stage 4 – The most advanced stage is characterized by tumors found throughout the thoracic cavity and in other areas of the body (such as the abdominal cavity or spinal cord).

Using PCI to Stage Biphasic Peritoneal Mesothelioma

Mesothelioma doctors use a system called the peritoneal cancer index (PCI) to determine the stage of peritoneal mesothelioma.

The system divides the abdomen into 13 sections, and each section receives a score from 0-3 depending on how much cancer is in each section. The scores are added up for a total PCI score, which correlates to one of the four stages used for most cancers: 

• Stage 1 – PCI score between 1 and 10
• Stage 2 – PCI score between 11 and 20
• Stage 3 – PCI score between 21 and 30
• Stage 4 – PCI score between 31 and higher