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Well-Differentiated Papillary Mesothelioma

Well-differentiated papillary mesothelioma is a type of benign tumor affecting the lungs or abdomen lining. It may be caused by exposure to asbestos and can be treated with surgery, chemotherapy, or radiation. The cells in this cancer are arranged in finger-like projections which gives it its name.

Key Facts About Well-Differentiated Papillary Mesothelioma

  • People with well-differentiated papillary mesothelioma often have no symptoms.
  • Well-differentiated papillary mesothelioma is a rare subtype of epithelioid mesothelioma.
  • The tumors are typically small, with one study recording a range of sizes from 0.1 cm to 2 cm.
  • It most often occurs in the peritoneum of women over a wide age range.
  • The tumors are usually benign, although some cases of WDPM turning malignant have been recorded.

What Is Well-Differentiated Papillary Mesothelioma?

Well-differentiated papillary mesothelioma is a rare subtype of epithelioid mesothelioma. Mesothelioma is a terminal cancer, but well-differentiated papillary mesothelioma is typically benign, meaning that it does not spread throughout the body and therefore has a fair prognosis.

Well-differentiated papillary mesothelioma most commonly arises in the peritoneal cavity but can also be found in the pleural cavity, pericardium, and tunica vaginalis.

What Do Well-Differentiated Papillary Mesothelioma Cells Look Like?

In well-differentiated papillary mesothelioma, papillary structures are lined by bland-looking, single-layered mesothelial cells.

The cells in a WDPM tumor grow into finger-like structures called papillae. This means that the cells grow in a pattern that resembles fingers. They are most often found on the surface of the tumor and can be seen as small projections or bumps.

What Causes Well-Differentiated Papillary Mesothelioma?

Asbestos is a naturally occurring mineral that has been mined for centuries. It was used in the past to make insulation, roofing shingles, and cement. It was also used in many household items, such as potting soil, vinyl floor tiles, and children’s toys.

Asbestos exposure can cause cancer of the lung or mesothelioma. The risk of developing mesothelioma increases with the duration and intensity of exposure to asbestos fibers.

This mineral is dangerous because it can break down into small enough fibers to enter the lungs. The fibers then irritate the lining of the lungs or cause cancerous changes in cells.

However, the link between asbestos exposure and well-differentiated papillary mesothelioma is less clear than for malignant types of mesothelioma. As there have been so few cases, researchers are unsure as to how it develops.

Symptoms of Well-Differentiated Papillary Mesothelioma

In many cases, well-differentiated papillary mesothelioma tumors have no symptoms. In some patients, well-differentiated papillary mesothelioma can cause pain. It can also cause fluid buildup in some patients.

One 2019 study found that all but one patient had zero symptoms and that most of the tumors were found incidentally during surgery for other causes.

Diagnosing Well-Differentiated Papillary Mesothelioma

Usually, healthcare providers will first conduct imaging tests to look for abnormalities in the body. However, it has been noted that well-differentiated papillary mesothelioma may not be detected by imaging. Additionally, if no symptoms are present, doctors would not know there was anything to look for. This is why well-differentiated papillary mesothelioma is typically found incidentally.

Biopsy is the most common and accurate way of diagnosing well-differentiated papillary mesothelioma. The biopsy will remove some tissue from the tumor and then look at it under a microscope. Healthcare providers will analyze the cells’ structure and determine what type they are.

What are the Treatment Options for Well-Differentiated Papillary Mesothelioma?

Because it is so rare, there is no standard treatment plan for well-differentiated papillary mesothelioma. However, some treatment options may include the following:

  • surgery
  • chemotherapy
  • radiation therapy

The surgery for well-differentiated papillary mesothelioma is to remove the tumor. Surgery is usually done by removing the entire tumor and some of the surrounding tissue. If there is a lot of fluid in the chest, this fluid may need to be drained before surgery can happen.

If the well-differentiated papillary mesothelioma has turned malignant, chemotherapy or radiation therapy may be needed.

Chemotherapy drugs work by stopping the growth of cancer cells and by killing them. They do this by interfering with the cell’s DNA. The drugs also interfere with the cell’s ability to divide and grow in order to create new healthy cells. However, chemo drugs can also affect healthy cells as well which is why it takes time for the body to recover from chemo treatments.

Radiation therapy targets the cancer cells with radiation so they can’t divide and grow as fast as they would without the treatment. It destroys these cells, which reduces the size of the tumor.

What is the Prognosis for Well-Differentiated Papillary Mesothelioma?

Because this is usually benign, it can typically be removed with surgery, and the prognosis is favorable.

Except in rare cases, where well-differentiated papillary mesothelioma can turn malignant, the tumor is removed using surgery and no further treatment is needed. However, because of the risk of it turning malignant, people with well-differentiated papillary mesothelioma should attend regular checkups to monitor for any additional issues.


Read on to learn the answers to frequently asked questions regarding well-differentiated papillary mesothelioma.

What is the difference between well-differentiated and poorly differentiated?

The different levels of differentiation are determined by how well the cells are organized in the tissue or organ. Cancer cells are compared to normal cells in an organ or tissue under a microscope. Well-differentiated cells look more similar to normal cells, whereas poorly differentiated cells look less normal.

What does it mean for a tumor to be well-differentiated?

Cancer cells are described as well-differentiated when they look more like normal cells under a microscope. They typically grow and spread more slowly than poorly differentiated or undifferentiated cancer cells.

Is papillary mesothelioma malignant?

Well-differentiated papillary mesothelioma is usually benign, meaning that it usually does not spread throughout the body. However, there have been some reported cases of it turning malignant, meaning cancerous.

Next Steps

After you’ve been diagnosed with well-differentiated papillary mesothelioma, the first thing to do is to consult your doctor. Your doctor will recommend a treatment plan that is tailored to your case. Treatment may include surgery, chemotherapy, and radiation therapy.

You should also talk to your family about the diagnosis, so they can understand what you are going through. It’s important to tell them about it so they can provide support and be there for you when needed.