Friction rub

Superficial, grating or creaking auscultatory sound produced when inflamed serosal or tendon surfaces (e.g., pleura, pericardium, tendon sheaths) rub against each other during cardiac cycles or respiration. Possible causes are pneumonia, pulmonary embolism, autoimmune diseases (rheumatoid arthritis, SLE), rib fracture, lung cancer, myocardial infarction (Dressler's syndrome), and radiotherapy.