Pathophysiology
Clinical meaning
Pleurisy (pleuritis) is inflammation of the pleura — the thin membrane lining the chest wall (parietal pleura) and covering the lungs (visceral pleura). Normally a small amount of lubricating fluid allows smooth lung movement. When inflamed, the rough surfaces rub against each other with every breath, causing sharp chest pain. The hallmark is sharp, stabbing chest pain that worsens with deep breathing, coughing, or sneezing and improves when holding the breath or leaning forward. A pleural friction rub — a grating, creaking sound synchronized with breathing — may be heard on auscultation (disappears if fluid accumulates between the layers). Common causes include viral infections (most common), pneumonia, pulmonary embolism, autoimmune diseases, rib fracture, and tuberculosis. Pleurisy itself is a symptom requiring identification and treatment of the underlying cause.