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Sarcomatoid Mesothelioma

Sarcomatoid mesothelioma is the least common of the cell types. Patients face a very poor prognosis, as it is the most aggressive subtype of mesothelioma and the most difficult to treat.

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Key Points

  • 1

    Sarcomatoid cells are the least common cell type, comprising 10% – 20% of cases.

  • 2

    The average life expectancy for patients with sarcomatoid mesothelioma is 1 year or less.

  • 3

    Sarcomatoid cells grow quickly and tend to spread to other organs.

  • 4

    Treatment options are limited and often confined to palliative.

Sarcomatoid mesothelioma is a less common cell type. Because the cells form in separate nodules, sarcomatoid mesothelioma metastasizes, or spreads, faster than other cell types. Sarcomatoid cells are also more resistant to treatment compared to other mesothelioma cell types. As a result, patients with sarcomatoid mesothelioma typically have limited treatment options and a poor prognosis.

Defining Characteristics of Sarcomatoid Mesothelioma Cells

When determining what type of mesothelioma a patient has, physicians will use histology, the study of cells, to analyze tumor cells and differentiate type. Sarcomatoid cells are sometimes hard to recognize, as they can appear very similar to normal, healthy cells. However, there are some defining characteristics, including the following:

  • Spindle-shaped
  • Enlarged, elongated nucleus
  • Sometimes have multiple nuclei
  • Spread apart, quick to metastasize

When comparing the malignant sarcomatoid cell type to malignant epithelial cells, the most common cell type of mesothelioma, epithelial cells are typically found clumped together, in uniform formations. Sarcomatoid cells, however, tend to be further apart, allowing them to spread quickly across far distances within the body (distant metastasis).

Sarcomatoid Mesothelioma Subtypes

Each of the three main cell types of mesothelioma has rare subtypes. There isn’t as much knowledge around rare subtypes as there is for biphasic, epithelial and sarcomatoid mesothelioma since there are a substantially smaller number of cases.

Sarcomatoid mesothelioma has three recognized subtypes, including transitional, lymphohistiocytoid and desmoplastic.

Rare Subtypes of Sarcomatoid Mesothelioma
Transitional Mesothelioma
  • Location: Pleura or peritoneum, pericardium (very rare)
  • Cell pattern: Plump, spindle-shaped cells
  • Metastasis: Local and distant
Lymphohistiocytoid Mesothelioma
  • Location: Peritoneum, pleura
  • Cell pattern: Large, polygonal/spindle-shaped cells, dense bundles of inflammatory immune cells
  • Metastasis: Local and distant with potential for recurrence after resection
Desmoplastic Mesothelioma
  • Location: Peritoneum, tunica vaginalis, pleura, areas of the male reproductive system
  • Cell pattern: Patternless
  • Metastasis: Local and distant with a resemblance to benign fibrous tissues

Aside from these three main subtypes of sarcomatoid mesothelioma, heterologous mesothelioma is sometimes considered a sarcomatoid subtype, as most cases are composed of sarcomatoid cells. Heterologous tumors are extremely rare, leaving prognosis for this subtype largely unknown. The main defining characteristic of heterologous tumors is the presence of cells from other bodily tissues, such as bone, cartilage and soft tissue. Many case studies refer to mesothelioma tumors having osteosarcomatous elements or chondrosarcomatous elements to define what cells are present within the mass.

  • Osteosarcomatous elements: Presence of bone cells within the cancerous mass.
  • Chondrosarcomatous elements: Presence of cartilage within the tumor.

Due to their rarity, sarcomatoid mesothelioma subtypes are easily misdiagnosed and may require multiple biopsies to make a differential diagnosis between mesothelioma and other cancers.

Diagnosing Sarcomatoid Mesothelioma

With all forms of cancer, early detection is important to provide a patient with the best opportunities for treatment and long-term survival. Sarcomatoid mesothelioma is no exception but can be hard to diagnose at an early stage due to the long latency period before symptoms emerge and its aggressive nature.

What Causes Malignant Sarcomatoid Mesothelioma?

If a patient comes in with symptoms of mesothelioma, a history of asbestos exposure is a huge signal to physicians that they may have the rare cancer. Airborne asbestos fibers can be ingested or inhaled, then become imbedded in organ linings, causing inflammation, scarring and mutation of normal cells into cancerous cells. Though asbestos is the only proven cause of malignant mesothelioma, there are other suspected risk factors that may make a patient more susceptible to developing the disease.

Symptoms of Sarcomatoid Mesothelioma

Different location types can alter the symptoms that a patient experiences, along with existing conditions, age and stage classification.

Common Symptoms of Sarcomatoid Mesothelioma
  • Abdominal pain
  • Chest pain
  • Cough
  • Difficulty breathing
  • Fatigue
  • Fever
  • Loss of appetite
  • Nausea
  • Weight loss

Mesothelioma Diagnostic Tests

After doctors gather patient history and symptom information, they will likely conduct imaging tests to confirm that there is a cancerous mass, as well as determine location and if the cancer has spread. Common image tests include CT scans, MRI scans, X-rays and PET scans. Results will also help guide physicians to understand where a biopsy should be performed.

There are many different types of biopsies that can be performed, varying based on location and how invasive they are. The main goal of a biopsy is to gather a tissue sample for analysis, to then determine the following:

  • Determine if tumor cells are cancerous or non-cancerous
  • Use histology and cytology to make a definitive mesothelioma diagnosis
  • Pinpoint cell type and stage of cancer
  • Develop an understanding of the most effective treatment plan

If sarcomatoid mesothelioma is suspected, seeking a mesothelioma specialist is often the best option to avoid common misdiagnoses, such as ovarian cancer, pneumonia, renal cell carcinoma, sarcomatoid carcinoma, fibrous pleurisy, localized fibrous tumors, fibrous histiocytoma and fibrosarcoma.

Treatment of Sarcomatoid Mesothelioma

Mesothelioma treatment can be extremely complicated, and sarcomatoid presents even more challenges due to its aggressive nature.

Conventional Treatments for Sarcomatoid Mesothelioma

Multimodal treatment plans are the most common route for mesothelioma patients, but conventional techniques aren’t usually as viable for sarcomatoid patients.

Sarcomatoid Response To Conventional Treatments
  • Sarcomatoid tumors are difficult to remove surgically
  • Usually used palliatively, such as with pleurodesis as complications usually outweigh surgical benefits
  • Sarcomatoid cells do not effectively respond to chemotherapy
  • Chemotherapy has shown little to no impact on median survival for sarcomatoid patients
  • Radiation therapy can be used to shrink tumors, but usually only used palliatively
  • Can treat symptoms such as difficulty breathing and pain

Compared to biphasic and epithelioid mesothelioma, sarcomatoid mesothelioma does not respond well to conventional treatments and will continue to spread quickly to distant organs. Each treatment comes with its own set of side effects, which will likely only worsen the symptoms that a sarcomatoid mesothelioma patient is experiencing.

Palliative Treatments for Sarcomatoid Mesothelioma

Sarcomatoid mesothelioma patients are often left with palliative treatments as their only option. Palliative care centers around patient comfort, providing cancer patients with the support and resources they need to maintain a high quality of life.

Extreme forms of palliative care include surgery, chemotherapy and radiation. When used palliatively, these techniques aim to reduce symptoms. Simple, yet highly effective forms of palliative care include yoga, meditation, therapy, support groups and job coaching. These methods can assist patients with finding peace of mind, staying comfortable, combatting treatment side effects and discovering support at any point during their treatment journey.

Sarcomatoid Mesothelioma Life Expectancy

Of the different types of mesothelioma, the sarcomatoid type has the worst prognosis due to its aggressive nature and poor response to treatment. Even with quick treatment at the first sight of symptoms, the average survival for sarcomatoid patients is only around 1 year or less.

While many patients face poor survival rate of less than a year, there are also some patients that have lived longer.

Even with such a grim prognosis, there is still hope for patients and their loved ones. Medical professionals continue to discover new potential options for treating the malignancy. Emerging treatments and clinical trials continue to show promise and offer hope for finding a cure.