Desmoplastic mesothelioma is a rare subtype of malignant mesothelioma. This type accounts for less than 10% of all cases. It is characterized by fibrous tissue with very few cells. Like other mesothelioma types, it is linked to asbestos exposure. Patients may benefit from immunotherapy.

01. Overview of Desmoplastic Mesothelioma

What Is Desmoplastic Mesothelioma?

Desmoplastic mesothelioma is a less common form of malignant mesothelioma. Specifically, it is a subtype of sarcomatoid mesothelioma. Forms of mesothelioma, such as desmoplastic, are linked to asbestos exposure.

Desmoplastic mesothelioma cells may develop in different areas of the body. They are most often found with malignant pleural mesothelioma, which develops in the lung lining. Desmoplastic mesothelioma has also been found in cases of peritoneal and pericardial mesothelioma.

Mesothelioma occurs in three main cell types:

  • Biphasic: This is a combination of epithelioid and sarcomatoid cells, also called mixed mesothelioma.
  • Epithelial: This is a cell type that lines many tissues. Mesothelioma occurs most often in this cell type. The disease may develop in the lining of the lungs, abdomen, heart or testicles.
  • Sarcomatoid: This is a less common mesothelioma cell type, most often impacting the lung lining. This cell type is generally associated with malignant pleural mesothelioma. However, these cells may also develop in the abdominal lining (peritoneum).

Within these three main cell types, there are different subtypes. Desmoplastic malignant mesothelioma (DMM) is a rare subtype of sarcomatoid mesothelioma.

This form of sarcomatoid (or spindle cell) mesothelioma may develop throughout mesothelial tissue. Desmoplastic tumors contain a very small number of scattered cells. These tumors are dense and made of fibrous, collagenized connective tissue.

02. Prognosis for Desmoplastic Mesothelioma

Survival and Prognosis for Desmoplastic Mesothelioma

A desmoplastic mesothelioma prognosis may vary for each patient. Because of its rarity, there are few published studies around survival rates for desmoplastic mesothelioma. Some studies reported survival rates ranging from about one month to 12 months for patients who underwent treatment.

Due to desmoplastic mesothelioma’s rarity, researchers have studied fewer cases than some other mesothelioma types. Without more studies, it is unclear how survival compares to general mesothelioma survival rates. Although more research is needed, scientists are learning about this subtype of mesothelioma.

Research on other mesothelioma types may provide some insight for desmoplastic mesothelioma survival time. Desmoplastic sarcomatoid mesothelioma is a non-epithelioid cell type. This means non-epithelioid research findings may apply to desmoplastic mesothelioma patients.

For example, a recent clinical trial treated non-epithelioid mesothelioma patients with immunotherapy. For these patients, the trial achieved a median survival of 18.1 months. Although possible, it is unclear if any participants had desmoplastic mesothelioma. Still, the results may be encouraging for those diagnosed with this subtype.

Doctors cannot yet estimate how immunotherapy may affect desmoplastic mesothelioma prognosis and survival. To gather more data on this, future studies and case reports are necessary.

After a mesothelioma diagnosis, a doctor can provide individualized care for a patient. This includes estimating a mesothelioma prognosis and treatment plan based on various disease factors.

03. Symptoms of Desmoplastic Mesothelioma

Desmoplastic Mesothelioma Symptoms

Being a less-studied form of mesothelioma, desmoplastic mesothelioma symptoms are not completely defined.

Symptoms in Desmoplastic Mesothelioma Patients

However, in some published case reports, researchers found patients had similar symptoms to those diagnosed with more common mesothelioma types. Future research may confirm specific desmoplastic mesothelioma symptoms.

Some symptoms associated with desmoplastic mesothelioma are also related to other conditions. For example, a respiratory infection could cause some of the same symptoms. A patient should talk with a doctor about any symptoms that could be due to mesothelioma. This is especially important for any patients with a known history of asbestos exposure. Their doctor may be able to run tests to determine the cause of the symptoms.

04. Diagnosing Desmoplastic Mesothelioma

Desmoplastic Mesothelioma Diagnosis

Diagnosing desmoplastic mesothelioma is similar to diagnosing mesothelioma in general. This means doctors may conduct various imaging scans and biopsies to make a diagnosis. However, this form of mesothelioma requires extra care with histology and cytology testing. These pathology tests involve microscopic analyses of specific cell types.

If doctors suspect malignant mesothelioma, the diagnostic process may include:

  • CT scan: This is an imaging test to help identify various details of a patient’s cancer diagnosis. CT scans can show abnormalities in normal organs and tissues.
  • Fluid biopsy: This is a fluid sample removed with a needle for diagnostic analysis. In some cases, fluid samples may not be enough to confirm the presence of mesothelioma.
  • Tissue biopsy: This is a tissue sample removed for diagnostic analysis. There are various methods a doctor can use to remove the sample.

A biopsy is the only way to confirm a mesothelioma diagnosis. Doctors may use a combination of tests to determine disease type, stage and other characteristics.

Desmoplastic Mesothelioma Diagnostic Guidelines

The following tissue characteristics support a diagnosis of desmoplastic mesothelioma:

  • Areas of malignant sarcomatoid cells are present.
  • More than 50% of the biopsy tissue sample contains dense, collagen-rich, fibrous tissue with very few cells.
  • The fibrous tissue has spread/grown into nearby fat or muscle.
  • The tissue sample contains areas of dead cells (tissue necrosis).
  • The tissue tests negative for thrombomodulin (a protein found on the outside of non-mesothelioma cells).
  • The tissue tests positive for calretinin, cytokeratin or p53 (the tumor suppressor gene).

Part of the diagnostic process may involve determining the patient’s mesothelioma stage. The stage alone does not dictate life expectancy or prognosis. It does, however, help doctors choose the optimal treatment for the patient.

Misdiagnosis of Desmoplastic Mesothelioma

Desmoplastic mesothelioma can be difficult to distinguish from another condition called pleural fibrosis. The condition is also called fibrous pleurisy. Desmoplastic mesothelioma and pleural fibrosis both develop in the chest wall. These two conditions have other similarities as well.

Pleural fibrosis affects the thin lung lining, called the pleura. This condition causes the pleura to develop scar tissue. Pleural fibrosis may cause a variety of symptoms.

Both desmoplastic mesothelioma and pleural fibrosis cause the development of fibrous scar tissue. Due to this, doctors may confuse the two conditions for each other. Careful analysis of biopsy tissue can help pathologists correctly identify desmoplastic mesothelioma. In general, this means using cytology and immunohistochemical markers during testing.

Patients diagnosed with pleural fibrosis may have a history of asbestos exposure. If so, it is important they share this information with their doctor. This can help doctors understand the need for more biopsy sample tests. These tests will help to either rule out or confirm desmoplastic malignant mesothelioma.

05. Treating Desmoplastic Mesothelioma

Desmoplastic Mesothelioma Treatment

Desmoplastic mesothelioma treatment varies for each case. Due to its rarity, this type of mesothelioma does not yet have a definitive treatment plan. Doctors usually follow general mesothelioma treatment practices, personalized for a patient’s needs.

Specific treatment approaches depend on several factors. These factors include tumor location, stage at diagnosis and overall patient health.

Regardless of the specific stage and location, palliative care is available throughout a patient’s mesothelioma journey. Palliative care methods can help patients manage symptoms, side effects and emotional needs.

Treatment Options for Desmoplastic Mesothelioma


  • Chemotherapy uses chemicals to kill cancer cells and limit their growth.
  • Chemotherapy may reduce metastasis (tumor growth). It may also improve a patient’s survival and quality of life.
  • Chemotherapy alone is not enough to cure mesothelioma. It may be more effective when combined with other treatments.

Experimental Treatments

  • Experimental treatments are promising therapies still being evaluated for mesothelioma. Researchers test these treatments, such as CAR T-cell therapy, in clinical trials.
  • For some mesothelioma patients, experimental treatments have improved life expectancy and other outcomes.
  • If interested, patients should discuss clinical trial eligibility with their doctor.


  • Immunotherapy stimulates a patient’s immune system to attack cancer cells.
  • Combination treatment plans may include other therapies with immunotherapy drugs.
  • Researchers continue testing this treatment for mesothelioma. Although immunotherapy cannot cure mesothelioma, it may extend patient life expectancy.

Multimodal Therapy

  • Multimodal therapy is when doctors combine multiple treatment methods.
  • Studies show combining treatments may improve various outcomes, such as survival.
  • For optimal results with mesothelioma treatment, doctors may recommend multimodal therapy.


  • Radiation therapy uses energy to damage and kill cancer cells. It may also prevent the spread of tumors.
  • Radiation is commonly used in combination with other treatments.
  • In some cases, radiation may improve symptoms and extend survival for mesothelioma patients.


  • Surgery is an operation to remove as much cancerous tissue as possible.
  • Surgery can be both a diagnostic tool and a treatment approach. As a treatment, it may have a variety of positive outcomes on a patient’s prognosis.
  • Surgery is a common treatment method for mesothelioma. For those who qualify, it may increase survival rates and improve symptoms.

A recent clinical trial showed significant survival benefits for patients with non-epithelioid cell types. This cell type includes desmoplastic mesothelioma. These results may change future treatments for patients with this form of mesothelioma.

There are many possible treatment options for mesothelioma patients. A mesothelioma doctor or expert can recommend the best options for each case. They can create personalized treatment plans for patients.

06. Causes of Desmoplastic Mesothelioma

How Does Asbestos Cause Desmoplastic Mesothelioma?

Asbestos is a known cause of malignant mesothelioma. However, some details specific to desmoplastic mesothelioma are unknown. The rarity of this subtype makes it difficult for scientists to study. Asbestos exposure may cause this subtype to develop like other forms of mesothelioma. Still, researchers have not determined exactly how it develops after asbestos exposure.

There are various published case reports on desmoplastic mesothelioma patients. Some of these case reports show numerous patients have an asbestos exposure history. These cases may have developed the same way researchers have suggested mesothelioma does in the pleura.

For instance, inhaling asbestos fibers may cause the fibers to move through lung tissue and lodge in the pleura. The fibers then cause inflammation, which may later lead to the development of mesothelioma tumor cells.

Patients should discuss any possible symptoms of mesothelioma with a doctor. It is also important for patients to disclose any history of asbestos exposure. With all this information, doctors can begin to provide a differential diagnosis.

Some symptom-free individuals may suspect or know of past asbestos exposure. They should still discuss this with a doctor, who may help monitor for signs of asbestos disease.