Pediatric Malignant Pleural Effusion

The pleural cavity is a thin layer of the sac that is lined with a serous membrane that encloses the lungs and separates them from the thoracic cage. An inner layer covers the surface of the lungs called the visceral pleura. The outer layer is the parietal pleural.A minuscule amount of fluid that is approximately 10 microliters thick can be found between the 2 layers.The amount of fluid in the pleural cavity is regulated by a fine balance in the oncotic and hydrostatic pressures between the pleural space and the intravascular components coupled with the perilymphatic drainage. The Frank-Starling law controls this process.

Up to 15 percent of patients with lung cancer develop malignant pleural effusions (MPEs). However, MPEs are not limited to lung cancers and might be a clinical presentation of either adjacent or metastatic carcinomas. Accordingly, MPEs can complicate malignant mesothelioma or might be present in metastatic cancers, including lung or distant sites such as breast or ovary), lymphoma, and hematologic malignancies. Generally, the presence of an MPE implies a poor prognosis.

In MPEs, cancer cells infiltrate into pleural tissue. Therefore, pleural tissue invasion by malignant cells is evident on pleural biopsy, and positive fluid cytology is predicted.

Specific malignancies, including small blue-round cell tumors, including rhabdomyosarcoma in the pediatric population, have the propensity for pleural metastasis and malignant pleural effusion.