The purulent infection in which the germs invade the pleural cavity and produce purulent exudate accumulation in the pleural cavity is called abscess chest. Acute abscess chest (within 6 weeks), chronic abscess chest (more than 6 weeks) Total abscess chest: pus spreads throughout the pleural cavity. Restricted: pus accumulates in a certain part of the chest cavity. Localized pus chest is often located between the lobes of the lung (interlobular pus chest), above the diaphragm (supradiaphragmatic pus chest), posterior and lateral to the pleural cavity (pus chest between lung and chest wall) and mediastinal surface (mediastinal pus chest). Suppurative pustules Tuberculous pustules Amoebic pustules The causative organisms of pustules mostly come from foci of infection in the lungs, and a few come from foci in other organs in the chest and mediastinum or other parts of the body. Pathogenic bacteria enter the pleural cavity by: 1. direct invasion or contamination of the pleural cavity due to trauma or surgery; 2. lymphatic route: liver abscess, subdiaphragmatic abscess, mediastinal abscess and purulent pericarditis; 3. hematologic route: sepsis and septicemia. The pathological process of septic chest is divided into three phases 1. Exudative phase: After bacterial invasion, the pleura is congested and initially exudes, and later leukocytes and fibrin increase and become pus. The pus increases rapidly, causing the lung to be compressed and the mediastinum to be pushed to the healthy side, causing respiratory and circulatory disorders. 2.Fibrin phase: pus contains a large amount of fibrin, which is deposited in the dirty and wall layer pleura, so that the lung, diaphragm and thorax respiratory activities are restricted. 3.Mechanization phase: fibrin mechanization forms fibrous plates and even calcification, making respiratory dysfunction more serious.