PLEURISY

inflammation of the pleura, the membrane that lines the thoracic cavity and folds in to cover the lungs. The inflamed membrane exudes varying quantities of fluid into the pleural cavity, between these two surfaces of the folded membrane. Depending on the amount of exudate, the pleurisy is described as simple or dry or fibrinous (in which case the amount of fluid is normal) or as pleurisy with effusion (in which case the amount of fluid accumulating in the pleural cavity is often extremely large). Because the pleura is well supplied with nerves, pleurisy can be very painful. The disease is commonly caused by infection in the underlying lung and, more rarely, by diffuse inflammatory conditions such as rheumatoid arthritis. Treatment of the disease includes pain relief and fluid evacuation; its main objective is correction of the underlying cause.