Medically Reviewed By:
Written By:
Last Modified September 2, 2022
This page features 6 Cited Research Articles
Fact Checked
Our fact-checking process begins with a thorough review of all sources to ensure they are high quality. Then we cross-check the facts with original medical or scientific reports published by those sources, or we validate the facts with reputable news organizations, medical and scientific experts and other health experts. Each page includes all sources for full transparency.
Reviewed is the nation’s most trusted mesothelioma resource

The Mesothelioma Center at has provided patients and their loved ones the most updated and reliable information on mesothelioma and asbestos exposure since 2006.

Our team of Patient Advocates includes a medical doctor, a registered nurse, health services administrators, veterans, VA-accredited Claims Agents, an oncology patient navigator and hospice care expert. Their combined expertise means we help any mesothelioma patient or loved one through every step of their cancer journey.

More than 30 contributors, including mesothelioma doctors, survivors, health care professionals and other experts, have peer-reviewed our website and written unique research-driven articles to ensure you get the highest-quality medical and health information.

About The Mesothelioma Center at

  • Assisting mesothelioma patients and their loved ones since 2006.
  • Helps more than 50% of mesothelioma patients diagnosed annually in the U.S.
  • A+ rating from the Better Business Bureau.
  • 5-star reviewed mesothelioma and support organization.
Learn More About Us


"My family has only the highest compliment for the assistance and support that we received from The Mesothelioma Center. This is a staff of compassionate and knowledgeable individuals who respect what your family is experiencing and who go the extra mile to make an unfortunate diagnosis less stressful. Information and assistance were provided by The Mesothelioma Center at no cost to our family."
Mesothelioma patient’s daughter
  • Google Review Rating
  • BBB Review Rating
Read Our Testimonials

Where Does Papillary Mesothelioma Develop?

The majority of well-differentiated papillary mesothelioma (WDPM) tumors develop in women, specifically in the abdominal cavity. Less commonly, doctors have found WDPM tumor growth on several of the body’s protective membranes, including the pleura (lining of the lungs), pericardium (heart sac) and tunica vaginalis (lining of the testes).

Is WDPM Cancerous?

From a medical standpoint, these tumors are practically benign. Studies have reported WDPM turning into malignant mesothelioma over time, although the chance of this happening is unlikely. Some people with WDPM have also experienced multiple recurrences after treatment.

A February 2019 study published in the Annals of Diagnostic Pathology observed 75 cases of WDPM diagnosed between 2000 and 2017 at Fudan University Shanghai Cancer Center in China.

Patients in the study included 58 females and 17 males ranging in age from 18 to 69 years. Of the 75 cases, only one turned cancerous.

A 2021 research report in Modern Pathology stated that solid papillary mesothelioma tumors appear to be either benign or very low-grade tumors that need to be separated from malignant mesotheliomas.

Is There an Asbestos Connection?

At this point, researchers are unsure whether papillary mesothelioma is linked to asbestos exposure. Some patients have a history of asbestos exposure, but most do not. The cause of this disease remains poorly understood.

According to a 2019 study published in Annals of Surgical Oncology, approximately 50 cases of WDPM in the peritoneum have been described in medical literature. There are also several small case reports of WDPM of the pleura. Another study indicated that there are fewer than 20 documented cases of testicular papillary mesothelioma.

Find a Top Mesothelioma Doctor
Gain access to top mesothelioma doctors and get help scheduling appointments.

Symptoms and Characteristics

well-differentiated papillary mesothelioma
well-differentiated papillary mesothelioma.

Many cases of well-differentiated papillary mesothelioma have no symptoms, but the disease has been known to cause pain and excessive fluid buildup in the pleura or abdomen of some patients.

WDPM of the tunica vaginalis can cause scrotal swelling or the formation of testicular lumps. In one study of 22 WDPM cases, only two patients reported to their doctors with symptoms. One patient experienced acute abdominal pain, and the other had chronic pelvic pain.

Primary Characteristics of WDPM

  • Well-differentiated tumors are low grade, meaning their cancer cells resemble healthy cells and grow and multiply at a slow rate.
  • The cancer does not invade nearby tissues or spread throughout the body.
  • In many cases, WDPM is completely inactive, showing no signs of cell division.
  • The tumor’s cells feature small, finger-like projections called papillae. These projections are lined by a single layer of flat mesothelial cells and can appear uniform, coarse or branching.
  • Papillae sometimes create round swirls of calcium known as psammoma bodies.
  • Tumors form white or grey nodules ranging from less than 1 centimeter in size to more than 3 centimeters.
  • WDPM can develop as a solitary mass or arise in many sites. The latter is known for more aggressive behavior.
  • Tumors are smaller than 1 centimeter in more than half of all cases.

Misdiagnosis and Challenges

Because well-differentiated papillary mesothelioma rarely causes symptoms, doctors usually discover tumor growth during an unrelated pelvic or abdominal surgery. WDPM can sometimes be found with an imaging test, such as a CT scan, but this technique isn’t sensitive enough to detect tumors smaller than 1 centimeter in size.

The only definitive procedure for diagnosing WDPM and other mesotheliomas is a biopsy — the collection of a tissue sample for laboratory analysis.

It is important for doctors to collect a comprehensive sample to prevent misdiagnosis, because highly aggressive malignant mesothelioma tumors sometimes feature areas of papillary cell growth.

Doctors may confuse WDPM with several other cancers and conditions:

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

Papillary Mesothelioma Treatment

With only a limited amount of research on the management of well-differentiated papillary mesothelioma, doctors have yet to reach a consensus on the most effective course of treatment.

Therapy usually involves a combination of the main types of mesothelioma treatment, including surgery, chemotherapy and radiation therapy.

Treatment options also depend on where the papillary mesothelioma tumors form.

For example, WDPM on the peritoneum may be treated with a combination of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy, also known as HIPEC. In the 2019 study published in Annals of Surgical Oncology, 37 of the 56 patients were treated with this combination.

A preview of the mesothelioma guide provided by The Mesothelioma Center
Get a Free Mesothelioma Guide
Receive a 200-page mesothelioma guide overnight. Learn about your diagnosis, top doctors and how to pay for treatment.

Prognosis and Survival Rate of Papillary Mesothelioma

The survival outlook for patients with well-differentiated papillary mesothelioma is significantly better than the prognosis of patients with most other mesothelioma cell types.

While only 5% to 10% of malignant mesothelioma patients survive five years after diagnosis, several patients with WDPM have survived for decades.

Median Survival for Well-Differentiated Papillary Mesothelioma
WDPM of the Pleura WDPM of the Peritoneum
6 years and 2 months 12 years
Source: American Journal of Surgical Pathology, 2004; Annals of Surgical Oncology, January 2019

Get the Compensation You Deserve
Laptop with screen video conference on kitchen counter
Watch Our Free Mesothelioma Webinars
Lab technician using a microscope in a lab
Immunotherapy & Mesothelioma Clinical Trials

Tell us what you think
Did this article help you?
How did this article help you?
What about this article isn’t helpful for you?
Did this article help you?

Thank you for your feedback. Would you like to speak with a Patient Advocate?