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Recurrent Pleural Effusion Could Signal High Mesothelioma Risk

Recurrent pleural effusion

The case of a Japanese woman with recurrent pleural effusion suggests the problem could be a precursor of malignant pleural mesothelioma.

Pleural effusion is a build-up of fluid on the space between the layers of the membrane that surrounds the lungs. It is common with mesothelioma and some other cancers. 

In the new case study, the patient had recurrent pleural effusion for 15 years before she developed mesothelioma in situ. This is the earliest stage of asbestos cancer, before it becomes invasive.

Her doctors say patients with similar problems should be tested for BAP1 loss and other signs of mesothelioma in situ. 

Understanding Recurrent Pleural Effusion

Pleural effusion is a side effect of several conditions including heart disease and cancer. Most mesothelioma patients eventually develop pleural effusion. 

The timing of this fluid build-up can vary from patient to patient. Some people do not have a problem with it until late in the disease process. Others, including the woman in the Japanese case study, deal with it for years. 

Recurrent pleural effusion is a sign that the body is trying to cope with some kind of internal threat. As fluid builds up in the layers of the pleura, it gets harder to breathe. Draining the fluid can temporarily relieve discomfort. 

A Slowly-Developing DIsease

The Japanese patient in the new case study was in her 70s. She had recurrent pleural effusion for 15 years before she developed pleural mesothelioma. Doctors kept draining off the fluid to help her feel better.

In the meantime, she developed mesothelioma in situ. Mesothelioma in situ is a group of cells on the surface of the mesothelial membrane that show BAP1 loss. With mesothelioma in situ, there is no tumor. But patients have a high risk of developing one in the future.

Doctors tracked the woman’s progress with immunohistochemical tests, gene tests, observations, and X-rays. It took 7 years for her mesothelioma in situ to turn into an invasive disease.

Testing May Be Key to Early Intervention

The Japanese study suggests that recurrent pleural effusion could signal mesothelioma in situ. The authors say patients with repeated lung fluid build-up should have a biopsy. They say pathologists should test the cells for loss of the BAP1 gene. 

“These results support a diagnostic strategy combining histomorphology with genomic-based assays including BAP1 IHC [immunohistochemistry] in biopsy tissues from a patient with recurrent pleural effusion,” they write.

An article published in Modern Pathology last year says finding mesothelioma in situ has the potential to improve mesothelioma survival. 

“Mesothelioma in situ…is associated with a high risk of developing invasive mesothelioma, but typically over a relatively protracted time, so that curable interventions may be possible,” the authors write. 

Mesothelioma is rare but usually fatal within a year. 


Kidaka, K, et al, “Development of mesothelioma in situ and its progression to invasive disease observed in a patient with uncontrolled pleural effusions for 15 years”, September 21, 2020, Pathology International, Case Reports, https://onlinelibrary.wiley.com/doi/10.1111/pin.13021

Chung, A, et al, “Malignant mesothelioma in situ: morphologic features and clinical outcome”, August 2, 2019, Nature, https://www.nature.com/articles/s41379-019-0347-0

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