Benign Mesothelioma

What Is Benign Mesothelioma?

Benign mesothelioma is a rare, noncancerous tumor that grows slowly, doesn’t spread and usually forms a single mass. It originates in mesothelial cells, which make up the mesothelium, the thin lining of the lungs, heart, abdomen and testes. It also has no established link to asbestos exposure, which sets it apart from the malignant form of the disease.

Key Facts About Benign Mesothelioma

1. Benign mesothelioma accounts for 10% of mesothelioma cases, according to the National Cancer Institute.
2. The incidence rate for the multicystic peritoneal type is under 1%.
3. Benign mesothelioma is more common in women in their 20s to 40s.
4. Men who develop benign mesothelioma have a mean age of 67..

A correct diagnosis and treatment plan are vital. They lead to the best outcomes in benign mesothelioma cases. Most people with benign mesothelioma can be treated and will fully recover. However, if tumors return they may become malignant. For this reason, doctors must continue to watch for new tumors.

Benign Mesothelioma vs. Malignant Mesothelioma

Benign mesothelioma tumors differ from malignant ones because they don’t spread to other parts of the body and tend to grow more slowly. And unlike the multiple tumor nodules often seen in malignant mesothelioma, benign tumors usually form a single mass and respond well to treatment. As a result, people with benign mesothelioma generally have a more favorable outlook.

Benign and malignant mesothelioma share some symptoms, and benign tumors can still cause discomfort. Abdominal pain and shortness of breath occur with both types. However, weight loss is more common with malignant mesothelioma, whereas people with benign tumors often experience weight gain. 

Types of Benign Mesothelioma

There are several benign mesothelioma types. The tumors’ cell characteristics define each. The most common type is benign multicystic mesothelioma. But it has fewer than 200 reported cases. Well-differentiated papillary mesothelioma is rarer. There are only 180 documented cases.

Benign Mesothelioma Types

• Adenomatoid tumor: AT is a subtype of epithelial mesothelioma. It most often affects the uterus wall and the tunica vaginalis. It’s rare for this type to develop in the pleura.
• Benign multicystic peritoneal mesothelioma: BMPM occurs in the peritoneal cavity, most often in the pelvis. It mainly affects young and middle-aged women. It sometimes occurs in women with a history of abdominal surgery.
• Localized fibrous tumor: LFT affects the surface of mesothelial cells in the pleura. It can also occur in the pericardium, tunica vaginalis and peritoneum. About 50% of patients have no symptoms. When they occur, they include a cough, pain and breathlessness.
• Well-differentiated papillary tumor: WDPT is the most likely of the benign types to become cancerous over time. Most cases occur in the peritoneum of women 30 to 40 years of age.

Each benign type carries its own recurrence risk and likelihood of malignant transformation. For that reason, doctors monitor all patients after treatment and watch for signs of tumors returning. Early detection of recurrence gives patients the best chance at successful retreatment.

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Symptoms of Benign Mesothelioma

Benign mesothelioma symptoms vary depending on the affected organ and may include swelling, pain and noticeable lumps in the abdomen or pelvis. Tumors can grow large enough to harm nearby tissues and organs. Benign and malignant mesothelioma share many of the same symptoms.

Common Benign Mesothelioma Symptoms

• Abdominal pain
• Chest pain
• Chronic cough
• Fluid buildup
• Palpable masses
• Shortness of breath
• Weight gain

Benign pleural tumors may cause low blood sugar. Rarely, they may cause seizures or coma. These are also symptoms of malignant pleural mesothelioma. Other symptoms are fever, night sweats and weight loss. Symptoms of benign mesothelioma may be unclear in some cases. 

A 2021 report in the Annals of Medicine and Surgery noted a 25-year-old woman with unusual symptoms. She had constipation, a strong urge to urinate and irregular periods. This case highlights the challenges in diagnosing some benign mesotheliomas, as their symptoms can be nonspecific and easily mistaken for other conditions.

Diagnosing Benign Mesothelioma

A biopsy confirms whether a tumor’s cells are benign or malignant and is the most important step in diagnosing benign mesothelioma. Doctors typically begin with a physical exam and full medical history, then order blood tests and imaging scans before performing the biopsy. A pathologist then studies the tissue sample and prepares a report detailing the cell type and characteristics, a process known as histopathology.

Diagnostic Tools

• Biopsies: A biopsy collects a sample of cells for analysis under a microscope. Biopsies are the only way to confirm if a tumor is benign or malignant.
• Blood tests: Blood tests alone aren’t sufficient to diagnose benign mesothelioma. But they can help doctors detect abnormalities that may indicate the presence of a tumor.
• Imaging scans: X-rays, CT scans and MRIs can spot suspicious tissue and help identify the location of potential tumors. This helps doctors plan biopsies and surgery.

A biopsy also shows the specific cell type that makes up the benign tumor. This information is helpful in assessing the risk of cancer. Some cells have a lower risk of turning into malignant mesothelioma.

How Is Benign Mesothelioma Treated?

Surgery is the primary treatment for benign mesothelioma. For tumors in the abdomen, doctors may apply heated chemo during surgery to help reduce the chance of recurrence. Doctors don’t generally recommend postoperative systemic chemo.

Recurrence and Survival Rates

• 10-year disease-free rate with HIPEC: Approximately 80% of multicystic peritoneal patients remain disease-free 10 years after surgery with HIPEC.
• Peritoneal recurrence rate (without HIPEC): Approximately 50% of peritoneal cases recur without heated chemotherapy.
• Pleural recurrence rate: Approximately 3% of pleural benign mesothelioma cases recur after surgery.

Most patients with benign mesothelioma recover fully after surgery and return to normal life. Recurrence is possible, particularly in peritoneal cases, which is why doctors monitor patients closely in the years following treatment. Catching a recurrence early gives patients the best chance at successful retreatment.

Treating Benign Pleural Mesothelioma

Thoracotomy is a common surgical treatment for benign pleural mesothelioma. Depending on the case, this may involve removing a segment of the lung, an entire lobe or the whole lung. However, removal of the entire lung is infrequent in benign cases.

As with any surgery, there are potential risks. A common side effect after thoracotomy is pleural effusion, which is the buildup of fluid in the pleural space around the lungs. This fluid can put pressure on the lungs and heart and may require the placement of a chest drain to remove it.

Treating Benign Peritoneal Mesothelioma

Doctors use cytoreductive surgery to remove benign peritoneal mesothelioma tumors in the abdomen. After surgery, heated chemotherapy is applied, which has reduced the chance of tumor recurrence to about 20%.

In the past, doctors often performed laparotomy or laparoscopy to remove tumors. However, the cancer usually returned, especially in women. Recurrence rates after surgery ranged from 40% to 50% for women, compared with about 33% for men.

What Is the Prognosis for Benign Mesothelioma?

The outlook for benign mesothelioma is generally positive, especially when the tumors are fully removed through surgery. This type of mesothelioma doesn’t usually affect life expectancy. Most people recover well after surgery and return to normal, active lives.

Although benign mesothelioma isn’t cancerous, tumors can still come back. Abdominal tumors carry a higher chance of returning, with recurrence rates reaching up to 50% without HIPEC. Tumors that doctors don’t fully remove also carry a higher chance of growing back. When tumors return, doctors often use surgery again to manage the diagnosis.

There’s also a small chance benign mesothelioma could become malignant over time. A biopsy can confirm if the disease has become cancerous. If that happens, a person’s outlook or prognosis will likely change.

Common Questions About Benign Mesothelioma

Is benign mesothelioma cancer?

Benign mesothelioma isn’t cancer. It’s a noncancerous tumor that doesn’t spread to other parts of the body. But it can still cause symptoms and, in rare cases, may become malignant over time.

Can benign mesothelioma become malignant?

In rare cases, yes. Well-differentiated papillary tumor, or WDPT, carries the highest risk of malignant transformation among benign types. That’s why doctors recommend ongoing monitoring after treatment to watch for any changes.

Is surgery always necessary for benign mesothelioma?

Surgery is the most common treatment. For those who don’t qualify for surgery, doctors use chemo. Radiation may also be used in some cases.

Are there any long-term health risks with benign mesothelioma?

Tumors can return after treatment, and there’s a small chance they may become malignant over time. Regular follow-up appointments help doctors catch any changes early.

Should people diagnosed with benign mesothelioma make lifestyle changes?

It’s not clear if lifestyle changes reduce the risk of recurrence. It’s also unclear if lifestyle raises the risk of tumors turning malignant. Smoking, for example, doesn’t directly cause mesothelioma. But it can affect the body’s response to asbestos.

Good overall health can help you heal better after surgery. This can reduce recovery time. Chemo and radiation can lower immunity. A healthy lifestyle can improve immunity. Diet and exercise can benefit the immune system.

What follow-up is recommended after treatment?

Your doctor will likely schedule you for imaging scans. These screenings may be every 3 or 4 months at first. It’s important to check for recurrence.  

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