Sarcomatoid Mesothelioma

Sarcomatoid: The Most Aggressive Mesothelioma Cell Type

Sarcomatoid mesothelioma is sometimes referred to as sarcomatous, spindle or diffuse malignant fibrous mesothelioma.

Spindle refers to the appearance of the cells when viewed under a microscope. They are long and spindle-shaped.

Diffuse and fibrous describes how the tumors appear within the pleural membrane that surrounds the lungs and lines the chest cavity. Sarcomatoid tumors can merge to form a sheet-like, fibrous mass on the pleural membrane.

Sarcomatoid mesothelioma is caused by the inhalation of asbestos fibers. The mutations in mesothelial cells caused by asbestos exposure develop into sarcomatoid mesothelioma.

It is the least common of all of the types of mesothelioma. Compared to epithelial and biphasic types of mesothelioma, it is also the most aggressive and resistant to treatment.

Nearly all sarcomatoid mesotheliomas are pleural. Fewer than 30 documented cases have occurred in people with peritoneal mesothelioma.

Sarcomatoid Mesothelioma Facts

• Location: Almost exclusively in the pleural membrane.
• Treatment: Chemotherapy, radiation therapy and immunotherapy. Some patients may qualify for surgery.
• Prognosis: Less than six months.

Diagnosis of Sarcomatoid Mesothelioma

Mesothelioma is easily misdiagnosed because signs of the disease mimic other, less serious conditions.

A 2018 study published in Lung Cancer describes a new approach for more accurate sarcomatoid mesothelioma diagnosis. Tests for the BAP1 and MTAP genes were 100% accurate for distinguishing sarcomatoid mesothelioma from fibrous pleuritis.

However, most doctors still use the traditional methods of determining a diagnosis.

Once a doctor has ruled out other causes of ongoing symptoms, they will order imaging studies such as X-rays, a CT scan or an MRI. These tests reveal abnormalities in the chest, but they do not reveal exactly what is causing these changes.

If your imaging studies suggest cancer, your doctor will refer you for a biopsy, which is a small sample of the tumor for analysis and identification under the microscope. A biopsy can be obtained using a needle under CT scan guidance or in a small outpatient procedure performed by a thoracic surgeon.

Surgeons often use thoroscopy or video-assisted thoracic surgery procedures to biopsy mesothelioma. These techniques can increase the chances of an accurate diagnosis.

Seeking a mesothelioma specialty team is important, too, because this group will include pathologists skilled in this diagnosis.

Common Misdiagnoses for Sarcomatoid Mesothelioma

Sarcomatoid cells present an extra level of difficulty to obtaining an accurate diagnosis.

They are easily misdiagnosed as other cancers and some noncancer conditions.

• Pleural liposarcoma
• Fibrous pleurisy or pleuritis
• Sarcoma or fibrosarcoma
• Malignant fibrous histiocytoma (also called undifferentiated pleomorphic sarcoma)
• Localized fibrous tumors
• Metastasized renal cell carcinoma
• Solitary fibrous tumor of the pleura (hemangiopericytoma)

Symptoms of Sarcomatoid Mesothelioma

Most patients experience nonspecific symptoms such as cough, shortness of breath and chest pain prior to diagnosis.

As the disease progresses, symptoms become more serious.

• Shortness of breath
• Prolonged hoarseness
• Persistent cough
• Coughing up blood
• Low blood oxygen levels
• Anemia (low iron)
• Weight loss and weakness
• Abdominal “fullness”
• Lack of appetite, anorexia and nausea
• Fatigue and extreme tiredness

Sarcomatoid Mesothelioma Treatment

A 2019 study published in The Annals of Thoracic Surgery found many patients do not receive treatment consistent with national guidelines on the management of malignant pleural mesothelioma.

The most important way to ensure you receive optimal care is to be treated at a reputable cancer center with experience managing this rare, asbestos-related disease.

Stage and location of the cancer typically determines the primary mesothelioma treatment options, which include surgery, chemotherapy and radiation therapy.

Surgery

Surgery is challenging because sarcomatoid tumors are rigid, often spread over large areas and can grow into the chest wall.

All of these features mean surgery alone isn’t likely to be effective for complete tumor removal. In some cases, mesothelioma surgery may not be an option for patients with sarcomatoid disease.

Because of the aggressive nature of sarcomatoid mesothelioma, the cancer has a tendency to return relatively soon, even after extensive surgery. For these reasons, surgical resection is usually not recommended for sarcomatoid pleural mesothelioma.

A 2020 study published in Translational Lung Cancer Research confirmed that surgeons do not operate on patients with sarcomatoid mesothelioma because they do not show the same benefit as patients with epithelioid mesothelioma.

With peritoneal mesothelioma tumors, the cancer can grow into or encase the soft internal organs of the abdomen.

Chemotherapy

The standard chemotherapy for treating pleural mesothelioma is a combination of Alimta (pemetrexed) plus cisplatin or carboplatin. This includes sarcomatoid cell type, which is found almost exclusively in the pleural membrane.

Radiation Therapy

Radiation therapy is not considered curative for mesothelioma. However, it can improve quality and length of life for some patients. It can be used as part of a palliative care plan to reduce symptom severity.

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Prognosis

The median survival for patients with sarcomatoid tumors is typically less than six months, but some patients live longer.

Patients with the lymphohistiocytoid cell subtype have survived as long as six years.

Prognosis estimates are based on past data. As treatment options improve and newer, cutting-edge therapies are employed, prognosis typically improves as well. This effect isn’t captured in current survival rate statistics.

If you are interested in a clinical trial that may improve prognosis, seek treatment at a specialty mesothelioma treatment facility.

Rare Mesothelioma Variants

Transitional Mesothelioma

This variant tends to grow and spread in ways similar to other sarcomatoid mesotheliomas. It has plump spindle-shaped cells, which help pathologists differentiate it from other cells.

Lymphohistiocytoid Mesothelioma

These tumors contain inflammatory and immune cells. Lymphohistiocytoid variant makes up less than 1% of all mesotheliomas. Some patients with this cancer have better-than-average life expectancy.

Desmoplastic Mesothelioma

This variant is a sarcomatoid subtype. It is one of the most difficult to diagnose. Half or more of the tumor shows no discernible pattern of growth. Desmoplastic type accounts for approximately 5% of all mesotheliomas.

Common Questions About Sarcomatoid Mesothelioma

What do I need to know about sarcomatoid mesothelioma?

• Sarcomatoid is the most aggressive and fastest spreading mesothelioma cell type and has the lowest average survival rate.
• It makes up 10% to 20% of all mesothelioma cases.
• It is more resistant to treatment than other types.
• However, clinical trials are testing new therapies for sarcomatoid mesothelioma and may be available to you through your physician.

How do I find a doctor who treats sarcomatoid mesothelioma?

All mesothelioma doctors have studied sarcomatoid mesothelioma and received training on how to treat this specific cell type. These specialists know the right kind of treatments and approaches that best control sarcomatoid mesothelioma. They also can connect you to clinical trials designed for patients with this cell type.

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Karen Selby, RN

Registered Nurse and Patient Advocate

Karen Selby joined Asbestos.com in 2009. She is a registered nurse with a background in oncology and thoracic surgery and was the regional director of a tissue bank before becoming a Patient Advocate at The Mesothelioma Center. Karen has assisted surgeons with thoracic surgeries such as lung resections, lung transplants, pneumonectomies, pleurectomies and wedge resections. She is also a member of the Academy of Oncology Nurse & Patient Navigators.

Edited by Walter Pacheco

Medical Review By Dr. Jacques Fontaine