Lung abscess

Accumulation of pus in lung tissue, which may have various causes; the condition is rare today. An abscess is a cavity in tissue filled with pus, usually caused by an inflammatory process resulting from bacterial infection. The cavity formed is encapsulated in tissue containing numerous inflammation cells. A lung abscess can result from closure of one of the smaller branches of the air passages by a tumour or foreign body that has ‘gone down the wrong way’ and come to rest in the lung. Bacterial inflammation can develop in the tissue behind the closure. The normal immune mechanism brings about encapsulation of the inflammation, and an abscess is formed. Bacteria may also be carried to the lungs by the blood from a source of infection elsewhere in the body, thus causing an abscess in this way. Another possible source is tuberculosis. Tuberculosis bacteria may be inhaled and cause abscesses in the lungs; these are encapsulated, forming the ‘caverns’ typical of tuberculosis. Lung abscesses irritate the lung and cause a ticklish cough. Sometimes the patient coughs up pus or blood, and there may be general symptoms such as fever and malaise. Symptoms that suggest a lung abscess should be followed up by checking with a stethoscope and X-rays of the lungs. Treatment should be in hospital, and involves surgery or medication ac-