Papillary Mesothelioma

Expert Fact Checked

This page was medically reviewed by James Stevenson, M.D. on March 10, 2019. For information on our content creation and review process read our editorial guidelines. If you notice an error or have comments or questions on our content please contact us.

James Stevenson, M.D. Thoracic Medical Oncologist

Well-differentiated papillary mesothelioma (WDPM) is a rare type of epithelial mesothelioma. Epithelial mesothelioma is the most common cell type of the cancer. Papillary mesothelioma can be connected to asbestos exposure. Many papillary mesothelioma tumors are benign with a favorable prognosis.

01. What Is Papillary Mesothelioma?

What Is Papillary Mesothelioma?

Papillary mesothelioma is a rare subtype of epithelial mesothelioma. It is often referred to as well-differentiated papillary mesothelioma (WDPM).

Papillary mesothelioma can occur in the linings of the abdomen (peritoneum), lungs (pleura) and testicles (tunica vaginalis).

Characteristics of papillary mesothelioma include:

  • Cell pattern: WDPM cells can be round or oval. The cells form finger-like projections called papillae.
  • Cell growth: WDPM cell growth is slow and microscopic. This growth pattern differentiates epithelial mesothelioma from malignant sarcomatoid mesothelioma. In contrast, sarcomatoid cells exhibit aggressive behavior and rapid growth.
  • Tumor location: Papillary mesothelioma affects cells in the linings of internal organs.
  • Patient demographic: WDPM is most common in young women, especially those with a history of endometriosis and ovarian cancer.
  • Unique calcification: In rare cases, papillary cancers may form psammoma bodies. Psammoma bodies are areas of calcification within the tumor.

Identifying tumor cell characteristics can help differentiate papillary mesothelioma from other mesothelioma subtypes.

Is Papillary Mesothelioma Benign?

Papillary mesothelioma is typically benign.

Some researchers have reported WDPM becoming malignant over a period of years. However, others have concluded WDPM is not a precursor to malignant mesothelioma. Conflicting information may be due to initial misdiagnosis of malignant mesothelioma as WDPM.

Due to the disease’s benign nature, WDPM is not prone to recurrence after treatment. Patients often experience no symptoms and live many years with this condition.

02. Papillary Mesothelioma & Asbestos

Well-Differentiated Papillary Mesothelioma and Asbestos

Papillary mesothelioma has been linked to asbestos exposure. In a review of 24 pleural WDPM cases, half of the patients had confirmed occupational asbestos exposure.

Published cases of papillary mesothelioma are rare. The disease is prone to misdiagnosis or being left undiagnosed altogether. These factors make the condition difficult to study.

Asbestos exposure itself is also difficult to track. Occupational asbestos exposure is the most common cause of mesothelioma. However, individuals may be exposed at home, school and many other locations.

Due to this lack of data, it is difficult to measure the prevalence of papillary mesothelioma in asbestos-exposed individuals.

03. Papillary Mesothelioma Symptoms

Symptoms of Papillary Mesothelioma

The majority of patients diagnosed with papillary mesothelioma show no symptoms.

One MD Anderson Cancer Center study reviewed 26 female papillary mesothelioma patients. In this study, only two patients presented symptoms. However, any reported symptoms can help physicians reach an accurate diagnosis.

Possible Symptoms of Papillary Mesothelioma by Location

Papillary Mesothelioma of the Peritoneum

Papillary Mesothelioma of the Pleura

Papillary Mesothelioma of the Tunica Vaginalis

  • Scrotal nodules
  • Scrotal swelling
  • Fluid-filled sac around scrotum (hydrocele)
04. Diagnosing Papillary Mesothelioma

Diagnosing Well-Differentiated Papillary Mesothelioma

Papillary mesothelioma diagnosis often occurs incidentally during other procedures.

However, well-differentiated papillary mesothelioma can be discovered in several ways, including:

  • Imaging scans: X-rays and CT scans may be able to identify WDPM tumors
  • Biopsy: Several types of biopsies may diagnose WDPM. These include laparoscopic biopsy, open lung biopsy and thoracoscopic pleural biopsy
  • Histology: The study of microscopic tissue structure
  • Immunohistochemistry: This process identifies unique cell proteins using a visible stain

These methods may be combined to confirm a diagnosis. However, biopsies are the only way to definitively diagnose papillary mesothelioma. A biopsy can characterize tumor cells, including mesothelioma type and stage. Biopsies are crucial for a differential diagnosis and preventing cancer misdiagnosis.

Due to its rarity, papillary mesothelioma is prone to misdiagnosis.

Potential Misdiagnoses of Papillary Mesothelioma

  • Appendicitis
  • Acute cholecystitis
  • Clear cell carcinoma
  • Incarcerated umbilical hernia

To prevent misdiagnosis, physicians will also observe symptoms and common co-occurring conditions.

Conditions associated with papillary mesothelioma include:

  • Colorectal cancer
  • Ovarian cancer
  • Endometriosis

The presence of the conditions in conjunction with WDPM has been observed in a few patients. There is not enough data for the conditions to be considered “risk factors.” However, they may assist doctors with correctly diagnosing papillary mesothelioma.

Accurate diagnosis is important to ensure the disease is treated correctly.

05. Papillary Mesothelioma Prognosis

What Is the Prognosis for Papillary Mesothelioma?

WDPM is typically benign and has a very favorable mesothelioma prognosis.

In the MD Anderson Cancer Center study of 26 papillary mesothelioma patients:

  • 22 survived with no recurrence
  • 1 patient experienced recurrence of WDPM after four years
  • 3 patients died of other causes

Papillary mesothelioma has a low malignant potential. However, because research on WDPM is limited, long-term follow-ups and monitoring are recommended.

06. Papillary Mesothelioma Treatment

How Is Papillary Mesothelioma Treated?

Treatment is not always required for benign WDPM. However, treatment options for papillary mesothelioma may include:

Treatment for well-differentiated papillary mesothelioma depends on malignancy. Benign mesothelioma tumors are typically removed with complete surgical resection.

Are Chemotherapy and Radiation Therapy Useful for WDPM?

Treatment for WDPM may include chemotherapy drugs such as cisplatin, doxorubicin and oxaliplatin.

However, researchers in one study of peritoneal WDPM noted adjuvant chemotherapy “does not seem to bring added value” to surgical removal. Researchers suggest patients with inoperable tumors be monitored for progression rather than attempting more aggressive treatments.

Researchers in a study of pleural WDPM found no evidence suggesting chemotherapy or radiation were beneficial.

Ultimately, more research is needed for a standard treatment plan for papillary mesothelioma. Patients should seek professional medical advice to establish an individualized mesothelioma treatment plan.

*Image Attribution: NephronCC BY-SA 3.0, via Wikimedia Commons