Key Points about Mesothelioma Cell Types
- The three main types of mesothelioma cells are epithelioid, sarcomatoid, and biphasic
- The study of cells is known as histology, a branch of biology and medicine
- By studying cancer cells, scientists can learn about important cell behaviors and features
- Knowing the specific cell features aids in diagnosis and impacts treatment and prognosis
Most malignancies, including mesothelioma, exhibit wide variations of tumor cell properties and functions. Cell typing, done under the histology umbrella, enables tumor cells to be grouped based on their appearance and features. This has particular importance because the groups, known as mesothelioma cell types, differ in their rates of growth, propensity to metastasize, likelihood to respond well to treatment, and impact on prognosis.
In fact, some investigators have found that, compared to stage, mesothelioma cell type may actually be a stronger predictor of survival. The three principal mesothelioma cell types are:
Each cell type exhibits substantially different tumor behavior. Further, each cell type also has a number of subtypes.
Mesothelioma Histology Involves The Study Of Cancer Cells
In biology, histology is the study of the body’s cells on a microscopic level, where scientists can see the structure and makeup of each cell. Specifically, mesothelioma histology, which studies cancerous mesothelial cells, is actually a branch of histopathology, or the study of diseased cells. This allows doctors to examine and then classify types of cells, which is crucial for an accurate diagnosis and developing an effective treatment plan.
Diagnosing Cell Type
To come to a diagnosis, the following steps are generally involved:
- Biopsy — Tissue or fluid is collected for examination
- Analysis — Scientists run the tissue through a chemical process that reveals its microscopic structures
- Typing — The sample is then studied and classified as a specific cell type based on its observable characteristics
Immunohistochemistry involves analyzing the cells for visual markers that indicate interaction between antibodies and proteins; various antibodies are applied to tissue samples in this process. Studies have found that immunohistochemistry improves the accuracy of a mesothelioma cell diagnosis, and it should be factored in along with other diagnostic protocols.
Epithelioid mesothelioma, the most common malignant mesothelioma cell type, accounts for 50-70% of all mesothelioma cases. As its name implies, it is the mutation of epithelial cells. Individual cells are known to be relatively uniform in shape and with a uniquely “tubular” appearance. When the cell is viewed under intense magnification, the cell nuclei is known to be distinct from other cell nuclei.
This cell type has the best prognosis.
Sarcomatoid mesothelioma, the least common type, is a rare malignant cell type and only accounts for between 10-15% of all mesothelioma cases. Sarcomatoid mesothelioma cells are oval shaped, but consistently irregular and not as uniform as epithelioid mesothelioma cells. The nucleus of sarcomatoid cells, so clear and distinguishable in epithelioid cells of the same type, is muddled and not as visible.
The oval shape of the sarcomatoid mesothelioma cells is common in other cell structures, and while it is not often associated with mesothelioma, they can closely mimic those of other malignancies, including those of sarcomatoid carcinoma and sarcoma. While sarcomatoid mesothelioma cells can manifest in other parts of the body, there are relatively rare within the lungs (the origin of most mesothelioma malignancies).
These cells metastasize more quickly than epithelioid cells and thus, sarcomatoid mesothelioma has a poorer prognosis.
Biphasic mesothelioma, also known as mixed cell type, has a combination of the two malignant cell types, epithelioid and sarcomatoid. Biphasic mesothelioma accounts for roughly 30% of all mesothelioma cases. Each cell type must make up at least 10% of the tumor for it to be diagnosed as biphasic.
Cancer behavior and spread, treatment, and prognosis of biphasic mesothelioma depends on the ratio of epithelioid cells to sarcomatoid cells. If there are more epithelioid cells, for example, treatment efficacy and prognosis may be more favorable, but it varies greatly.
Mesothelioma Cell Type Affects Treatment And Prognosis
There is debate over how much cell type plays a role in treatment. Some experts argue that, in determining treatment for mesothelioma patients, the difference in cell type is not a main factor. Instead, tumor location and stage of the cancer are the most important factors at play in developing a treatment plan. Cell type becomes more of a factor in determining how aggressive the treatment approach will be, and is also a factor in how favorable the prognosis is.
Other studies show that each cell type responds quite differently to treatments and can significantly impact prognosis, making accurate diagnosis of cell type highly important. Cell type can account for a difference of up to 6 to 7 months of survival.
Ultimately, there are a number of unique factors at play, all of which influence one another and play a role in determining an effective treatment plan and patient outcome. It’s important to talk with your doctor and to get a second opinion from a mesothelioma specialist to ensure highest accuracy in diagnosis, which will only improve treatment efficacy and prognosis.