Types of Mesothelioma

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This page was medically reviewed by James Stevenson, M.D. on February 22, 2019. For information on our content creation and review process read our editorial guidelines. If you notice an error or have comments or questions on our content please contact us.

James Stevenson, M.D. Thoracic Medical Oncologist

There are four types of malignant mesothelioma based on tumor location. Mesothelioma may form in the lining of the lungs (pleural), abdomen (peritoneal), heart (pericardial) or testicles. It’s also categorized by cancer cell type: epithelioid, sarcomatoid and biphasic. Common treatments: chemotherapy, radiation and surgery.

01. Types by Location

Mesothelioma Types by Location

Mesothelioma cancer develops after a person is exposed to asbestos fibers. Ten to fifty years after initial exposure, healthy cells mutate and become cancerous. These cells grow and multiply in the thin layer of cells lining the outside of internal organs (mesothelium). The cancer may form in the lining of the lungs, heart, abdomen or testicles. The location of the tumors is the primary method used to determine the type of mesothelioma.

Pleural Mesothelioma (Lungs)

Pleural mesothelioma forms in the lining of the lungs, known as the pleura. It is the most common form of the aggressive disease. Approximately 80 – 90% of all diagnosed cases of mesothelioma are pleural.

Pleural mesothelioma symptoms include:

  • Chest pain
  • Coughing
  • Fatigue
  • Shortness of breath

These symptoms are sometimes inaccurately associated with other diseases, such as lung cancer. Nonspecific symptoms and the long latency period can make diagnosing pleural mesothelioma difficult.

On average, pleural mesothelioma patients survive about 18 months after diagnosis. This form of the cancer has a one-year survival rate of about 73% and five-year survival rate of about 12%.

Peritoneal Mesothelioma (Abdomen)

Peritoneal mesothelioma is the second-most common type of the cancer and is diagnosed in about 15 – 20% of all mesothelioma cases. This type of mesothelioma affects the lining of the abdominal cavity (peritoneum).

Peritoneal mesothelioma symptoms include:

Due to advancements in treatments, peritoneal mesothelioma patients have a more favorable life expectancy than those with other forms of the disease. One of the most promising peritoneal treatments is surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC). At least 50% of patients who undergo surgery combined with HIPEC live for five years or more.

Peritoneal mesothelioma patients have a one-year survival rate of 92%, regardless of their treatment plan.

Pericardial Mesothelioma (Heart)

Pericardial mesothelioma tumors form in the lining of the heart (pericardium). This cancer is very rare. Fewer than 50 people receive pericardial mesothelioma diagnoses in the United States each year. This form of the disease accounts for about 1% of the total number of mesothelioma cases.

Pericardial mesothelioma symptoms include:

Because of the tumors’ proximity to the heart, patients may experience severe symptoms during the early stages of mesothelioma.

Due to its rarity, the general prognosis for pericardial mesothelioma is poor. Patients survive six months on average, with a one-year survival rate of 51%. In most cases, pericardial mesothelioma treatments are palliative and aim to reduce symptoms.

Testicular Mesothelioma

Testicular mesothelioma is diagnosed in less than 1% of all cases. Medical literature only describes approximately 100 cases. The cancer develops in the lining of the testicles (tunica vaginalis).

Testicular mesothelioma typically presents with the following symptoms:

  • A mass on the testicle
  • Testicular pain
  • Scrotal swelling caused by fluid buildup

Patients with this type of mesothelioma have a more favorable life expectancy than patients with other forms. Prognosis for testicular mesothelioma patients is two years on average. However, studies have shown testicular mesothelioma has a high rate of recurrence. Almost 93% of patients experience recurrent cancer within five years of their initial diagnosis.

02. Cell Types

Mesothelioma Cell Types

There are three main types of mesothelioma cells: epithelial, sarcomatoid and biphasic. Mesothelioma doctors consider cell type when creating a treatment plan because the cells respond differently to treatment. Doctors will use cell type with mesothelioma type when determining viable treatment options and patient prognosis.

Epithelioid Mesothelioma

Epithelioid Mesothelioma

Epithelioid mesothelioma is the most common cell type and accounts for about 70 – 80% of all mesothelioma cases. This cell type typically responds well to treatment and has a more favorable prognosis than other cell types. Patients with epithelioid mesothelioma have an average life expectancy of 12 – 24 months.

Sarcomatoid Mesothelioma

Sarcomatoid Mesothelioma

Sarcomatoid mesothelioma accounts for about 10 – 20% of all diagnosed mesothelioma cases. It is considered the most difficult to treat. Sarcomatoid cells are known for aggressive growth, often leaving patients with a less favorable prognosis of six months.

Biphasic Mesothelioma

Biphasic Mesothelioma

Biphasic mesothelioma, or mixed mesothelioma, contains epithelial and sarcomatoid cells within the mesothelioma tumors. With both types of cells present, prognosis varies depending on which cell type is dominant. Patients with more epithelial cells will likely have a more favorable response to treatment compared to those with more sarcomatoid cells.

Adenoid Mesothelioma

Rare Cell Types

Mesothelioma cells may sometimes be classified as rare subtypes of epithelial or sarcomatoid mesothelioma.

Rare subtypes include:

  • Adenomatoid mesothelioma
  • Cystic mesothelioma
  • Desmoplastic mesothelioma
  • Well-differentiated papillary mesothelioma
  • Small cell mesothelioma

Depending on the identified subtype, treatment options may be limited. Rare malignant mesothelioma cell types typically have a poor prognosis, often less than one year. However, some rare cell types may be benign and patients can live for years following diagnosis.

03. Malignant vs. Benign

Malignant vs. Benign Mesothelioma

Mesothelioma is categorized by the type of cells found in fluid or tissue samples taken from the body. The tumors can be either malignant (cancerous) or benign.

Malignant mesothelioma makes up the majority of diagnosed cases. Malignant tumors often grow or spread quickly, which can limit viable treatment options. As such, patients with malignant mesothelioma live an average of 12 – 21 months after diagnosis.

Benign mesothelioma is a non-cancerous form of the disease. These tumors have a low rate of recurrence and can often be completely resected with surgery. Benign tumors are typically localized, slow-growing and non-invasive (unlikely to spread). In some cases, benign mesothelioma tumors may potentially become malignant.

04. Treatment by Type

Mesothelioma Treatment by Type

Viable treatment options will depend on mesothelioma type and cell type.

There are three primary types of treatment available to patients:

Two or more treatments are often combined as part of a multimodal treatment plan.

Patients who are diagnosed with early-stage mesothelioma and are in generally good health may be candidates for more radical treatments. These may include surgical options, such as extrapleural pneumonectomy (EPP), pleurectomy/decortication (P/D) or peritoneal cytoreductive surgery (CRS).

When surgery isn’t an option, chemotherapy and/or radiation may be used. The specific treatment combination applied will vary on a case-by-case basis.

In addition to traditional treatments like surgery, there are also immunotherapy and targeted therapy options available through ongoing clinical trials.

Patients who are too ill to receive any curative treatment are given palliative therapies. The goal of these therapies is to reduce pain as part of end-of-life care.