Epithelioid Mesothelioma

Of all mesothelioma cases diagnosed, the epithelioid type is the most common. Also known as epithelial, it accounts for about 50% to 70% of all cases and typically occurs in pleural mesothelioma (affecting the lungs). This means that the cancerous tissue is made up mainly of epithelial cells.

Epithelial cells form the tissue that lines a surface on or in the body. This surface tissue is called an epithelium (plural: epithelia), and it forms the epidermis (the outer skin layer), inside of body cavities, the outside of many internal organs and the inside of tubes and ducts. The epithelia creates a barrier that can be impermeable (like the epidermis) or not (like in the intestines). It can also perform other functions, such as absorbing nutrients, secreting fluid and aiding in the movement of substances.

We all have epithelial cells, and at a normal rate, they are essential for our health and well being. However, if they begin to mutate and rapidly grow, cancer can result.

Sub-types of epithelial mesothelioma

The size, shape and formation of the epithelial cells determines which sub-type of epithelial mesothelioma you may have. Finding out which sub-type you have is important in making an effective treatment plan.
  • Single file (can be confused with breast cancer)
  • Diffuse – NOS
  • Glomeruloid
  • Small Cell
  • Poorly Differentiated (cells that are round, polygonal or irregularly shaped and can increase the risk of misdiagnosis)
  • Mucin Positive
  • Gaucher Cell-Like
  • Deciduioid Tubulopapillary
  • Glandular
  • Histiocytoid
  • Well Differentiated Papillary (WDPM)
  • Signet Ring
  • Multi cystic:
    Adenoid Cystic

Diagnosing epithelioid mesothelioma

Imaging scans, radiology, pathology, immunohistochemistry and a physical examination are all diagnostic tools. Epithelial mesothelioma can be misdiagnosed as lung adenocarcinoma (and vice versa). Research has found that abiopsy and immunohistochemical testing with calretinin and cytokeratin markers can help make a proper diagnosis1.

Once diagnosed, patients have an expected lifespan of about one year.

A better survival rate

Fortunately, epithelioid mesothelioma has been found to have a better survival rate than other types of this cancer. This may be for three reasons:

  1. It has been researched more than the other cellular types, so more is known about its development and how to prevent it. Because of this, more treatment options may be available and doctors can design a more effective treatment plan.
  2. Patients respond better to treatment. It is standard that treatment involves surgery, chemotherapy and radiation therapy.
  3. Epithelial cells may divide faster than other cell types, however they tend to stick to each more. This means that even though tumors grow faster, the cancer won’t spread as much to other tissues.

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