Papillary Mesothelioma

What Is Papillary Mesothelioma?

Papillary mesothelioma is a rare form of mesothelioma. It’s also called well-differentiated papillary mesothelioma and its tumors are low-grade. This means they grow slowly and are less likely to spread. This differs from malignant mesothelioma, which is aggressive and fast-growing.

Primary Characteristics of WDPM

• The tumor’s cells feature small finger-like projections called papillae.
• Papillae can create round swirls of calcium called psammoma bodies.
• Tumors are smaller than 1 centimeter in more than 50% of all cases.
• Tumors form white or grey nodules ranging from less than 1 centimeter to more than 3 centimeters.

Well-differentiated papillary tumors don’t invade nearby tissues or spread. WDPMT can develop as a solitary mass or arise in many sites. The latter has more aggressive behavior. WDPMT is inactive in some cases, showing no cell division.

Are Well-Differentiated Papillary Mesothelioma Tumors Cancerous?

Most experts don’t classify WDPM as a cancer. It’s generally considered less aggressive than malignant mesothelioma. WDPM is usually benign but can turn malignant in rare cases. 

Early detection helps manage the condition effectively. This reduces risks of progression.

Expert Take

Dr. Jacques Fontaine: How Your Tumor Location Affects Your Mesothelioma Treatment

View Transcript

Mesothelioma is a cancer coming from mesothelial lining. We have mesothelial lining around our lungs and our chest called pleura. We have mesothelial lining around our abdomen, peritoneal mesothelioma, and we also have mesothelial lining around the testicles as well as the pericardium.


Mesothelioma, which is a cancer of the lining of the mesothelial cells, can occur around the heart, pericardial mesothelioma, quite rare, and occur around the lungs, the pleural cavity, that’s called pleural mesothelioma, the most common type.


And the second most common type is around the intestine, around the belly, that’s called peritoneal type, and extremely rarely around the testicles. Of the different locations, the treatment in terms of chemotherapy or immunotherapy does not differ.


What makes us decide to use chemotherapy versus immunotherapy is not the location of the mesothelioma, but rather the subtype, meaning how does it look like under a microscope, the histological subtype. Is it epithelial, or is it sarcomatoid, or is it mixed? Now in terms of surgery, the surgery differs obviously in terms of the location in the body. So if we have pleural mesothelioma, we usually have a tendency to remove the whole lining around the lung, the lining around the chest wall, the lining around the heart and the diaphragm. If it’s perineal mesothelioma, we make an incision on the belly, and then we remove the lining around the belly, on the intestines, the capsule, sometimes around the liver, and the rectum. So the type of surgery differs in terms of location, but the type of systemic therapy, chemo or immunotherapy, is the same irrespective of the location of the mesothelioma.

Where Does Papillary Mesothelioma Develop?

Papillary mesothelioma typically develops in the abdominal cavity. It grows on protective membranes in specific areas. It mainly affects the peritoneum but can also develop in the pleura or tunica vaginalis.

• Peritoneum: Lining of the abdomen
• Pleura: Lining of the lungs
• Tunica Vaginalis: Lining around the testes

WDPM is more common in women. It’s typically diagnosed during the course of unrelated medical exams.

What Causes Papillary Mesothelioma?

The exact cause of papillary mesothelioma is unknown. Asbestos exposure is a risk factor for developing this rare disease. 

Many cases appear to develop without identifiable risk factors, making it challenging for researchers to pinpoint exact causes. Rare documented cases suggest some instances of WDPM may result from genetic mutations or environmental factors.

Is There an Asbestos Connection?

Exposure to asbestos may be involved in some WDPM cases, but the connection is less clear than with malignant mesothelioma. Experts suggest further research is needed to confirm any relationship.

Juan Namnun, a Philadelphia teacher, sued his local school district in 2022. He faced asbestos exposure from school buildings and received a diagnosis of papillary mesothelioma. 

“This is a systemic, long-standing issue that didn’t happen overnight,” said Namnun’s asbestos lawyer Thomas Bosworth. “I think that’s the most alarming part to me.”

The medical literature includes about 50 cases of WDPMT in the peritoneum, including a 2019 study in the Annals of Surgical Oncology. Some individuals with WDPM have no history of asbestos exposure but often have prior abdominal surgeries or long-standing inflammation in the affected tissues.

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Symptoms of Papillary Mesothelioma

Many cases of WDPM, particularly in the early stages, may be asymptomatic. They’re discovered incidentally during imaging or surgery for unrelated conditions.

Symptoms depend on the location of the tumor. If WDPMT develop in the chest, symptoms can include coughing or trouble breathing. In the abdomen, symptoms can include abdominal pain or digestive issues.

Papillary Mesothelioma Symptoms

• Abdominal pain or swelling
• Ascites (fluid buildup in the abdominal cavity)
• Chest pain or discomfort
• Difficulty breathing (dyspnea)
• Fatigue or weakness
• Heart palpitations or irregular heartbeat (if affecting the pericardium)
• Loss of appetite
• Nausea or digestive issues
• Persistent cough
• Pleural effusion (fluid buildup in the chest cavity)
• Unexplained weight loss

WDPMT of the tunica vaginalis can cause scrotal swelling or lumps. In a study of 22 WDPMT cases, only 2 patients reported symptoms to their doctors. One patient experienced acute abdominal pain, and the other had chronic pelvic pain.

Diagnosis of Papillary Mesothelioma

Diagnosing WDPM requires a biopsy to confirm the type of tumor. Imaging tests, like CT scans, are helpful but may not detect smaller growths. Biopsies provide the most accurate results.

Doctors usually discover this condition during pelvis or abdomen surgery. An imaging test, such as a CT scan, may find it. However, this technique isn’t sensitive enough to detect tumors smaller than 1 centimeter.

Misdiagnosis and Challenges

Doctors also look for negative markers while looking for signs of mesothelioma. These markers indicate that the tumor is likely not mesothelioma but another type of cancer. 

Common WDPMT Misdiagnoses

• Adenomatoid tumor
• Peritoneal carcinomatosis
• Reactive mesothelial hyperplasia
• Serous papillary carcinoma of the ovary
• Serous papillary carcinoma of the peritoneum
• Tuberculous peritonitis

One example of a negative marker is the PAX8 protein. Mesothelioma patients rarely test positive for PAX8. If detected, this could mean kidney, thyroid or female reproductive cancers.

Treatment Options for Papillary Mesothelioma

Therapy usually involves surgery, chemotherapy, radiation therapy or a combination of the main types of mesothelioma treatment. Treatment options also depend on where the papillary mesothelioma tumors form.

For abdominal cases, surgery combined with heated chemotherapy or HIPEC has shown the most success. This approach targets cancer cells directly in the abdominal cavity, improving outcomes while minimizing systemic side effects.

Papillary Mesothelioma Prognosis and Survival

Most WDPM patients have a good prognosis, with many living for years after diagnosis. With rare malignant cases survival rates are lower, but early treatment improves outcomes.

Malignant mesothelioma’s prognosis is typically not as good as the prognosis for WPDM. For comparison, malignant mesothelioma’s median survival is 12-21 months, while benign WDPM has much higher survival rates. Studies show patients who undergo surgery and heated chemotherapy for peritoneal cases often achieve long-term remission.

Common Questions About Papillary Mesothelioma

Can Papillary Mesothelioma Be Detected Early Without Symptoms?

Detecting papillary mesothelioma early is difficult. It’s a rare disease and its symptoms are nonspecific. This means it shares symptoms with other more common conditions. 

Routine screenings or monitoring of people potentially at risk, such as those with a history of abdominal surgeries or asbestos exposure, may help identify WDPM before it progresses. Most people only receive a diagnosis after their symptoms develop, prompting further investigation.

Are There Genetic or Family Risk Factors for Papillary Mesothelioma?

Researchers haven’t established genetic or familial links to well-differentiated papillary mesothelioma. Unlike some cancers, WDPM doesn’t appear to run in families. However, ongoing research seeks to uncover whether certain genetic factors or specific mutations could lead to WDPM.

Are There Clinical Trials for Papillary Mesothelioma?

WDPM is very rare, so few clinical trials explicitly target it. However, broader mesothelioma studies often include patients with WDPM. 

These trials usually use innovative therapies, procedures or combinations of treatments. Patients can explore clinical trial opportunities via the National Cancer Institute, specialized cancer centers or speaking with a Patient Advocate.

How Does WDPM Impact Fertility in Women?

There is limited research on WDPM’s impact on fertility. Since many cases involve the peritoneum, treatment options like surgery and chemotherapy could potentially affect reproductive organs or overall fertility. Women diagnosed with WDPM are encouraged to consult a specialist to discuss fertility preservation options before starting treatment.