What Are Pleurisy and Pleural Effusion?

The pleura are two thin layers of smooth tissue that line the chest cavity and surround the lungs. Ordinarily, a small amount of fluid lubricates the two layers.

Pleurisy, also known as pleuritis, is an inflammation of the pleura. Pleural effusion is when there is buildup of fluid between the two layers. Both conditions can cause considerable pain when you inhale and exhale. The pain can be in the chest or back, or radiate up into the shoulder.

About 1.5 million Americans are diagnosed with pleural effusion every year.