Mesothelioma pathology is the study of the causes and effects of the disease. Patients who are suspected of having mesothelioma require a pathology report to determine their diagnosis, which includes cytological and histological testing of fluid and tissue samples.

Breaking Down the Pathological Process

Diagnosing mesothelioma begins with a pathology report. These reports are made up of data from cytological and histological tests performed on a patient who is suspected of having mesothelioma cancer. It is from these tests like fine needle aspirations and tissue biopsies that oncologists are able to determine the cell type of the patient’s mesothelioma and form a more accurate diagnosis, which in turn determines what the correct treatment should be.

The pathological process can be broken down into two subsections:

  • Cytology

    Cytology is simply the study of cell structure and their functions. In the case of studying mesothelioma, cytological analysis of fluid buildup is an essential next step after imaging tests have been conducted to find evidence of malignant cells. By using a needle biopsy, doctors can extract a sample of the fluid that builds up in the pleura or peritoneum, stain it, and see if there are malignant cells that react to the stain.

    This is a much less invasive procedure than a tissue biopsy and can sometimes definitively diagnose mesothelioma before tissue samples are taken. Often times there are not enough malignant cells in a fluid sample to determine if a patient does, in fact, have mesothelioma cancer. This is why most oncologists will require a tissue biopsy and a histological analysis to make a definitive diagnosis.

  • Histology

    Histology is the study of tissue under a microscope. It is almost always conducted in unison with cytological tests to help make a definitive diagnosis of mesothelioma. Similar to cytological tests, histology is used to analyze cells from tissue samples taken from a patient suspected of having mesothelioma. Histopathology is similar to cytology but the stains are applied to tissue samples that contain more cells.

    Immunohistochemistry tests are essential for accurately diagnosing mesothelioma because cells can resemble other forms of cancer under the microscope. Through these processes, oncologists are able to understand what cell type a patient’s mesothelioma is made up of, which can influence decisions in choosing treatment options.

Determining Mesothelioma Cell Types

One of the main reasons to get a mesothelioma pathology report is to determine the exact cell type of a patient’s cancer. Mesothelioma tumors can be made up of three varieties of cells, each with their own unique qualities and effects on the patient’s prognosis.

  • Epithelioid

    Epithelioid cells are the most common cell type of mesothelioma. Their characteristics include a clearly defined, elongated egg-shape with a visible nuclei. It is the most treatable cell type because while the cells exhibit rapid cell division, they tend to stick together making them easier to remove surgically.

  • Sarcomatoid

    Sarcomatoid cells are the least common cell type of mesothelioma. These cells are spindle-shaped, often with elongated or multiple nuclei. Sarcomatoid cells spread more quickly throughout the body since they do not clump together. Metastasis is much more likely when diagnosed with this cell type.

  • Biphasic

    Biphasic mesothelioma is made up of a combination of epithelioid and sarcomatoid cells. It is the second most common cell type. Treatment is based off of which cell type is more prevalent. Typically, if the patient has more epithelioid cells than sarcomatoid then they are projected to have a better life expectancy.