Lung abscess overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Lung abscess is necrosis of the pulmonary tissue and formation of cavities (more than 2 cm)[1] containing necrotic debris or fluid caused by microbial infection.This pus-filled cavity is often caused by aspiration, which may occur during altered consciousness. Alcoholism is the most common condition predisposing to lung abscesses.Lung Abscess is considered primary(60%) when it results from existing lung parenchymal process and is termed secondary when it complicates another process e.g. vascular emboli or follows rupture of extrapulmonary abscess into lung.
Historical Perspective
Lung abscess has been a disease entity since the days of Hippocrates. Postural physiotherapy had been the mainstay of treatment until Harold Neuhof described his concept of new one-stage open drainage for the acute abscess in 1930's. With the invention of antibiotics in late 1940's and their promising results led the change in management of lung abscess.
Pathophysiology
Aspiration of anaerobic bacteria is the inciting event for the development of lung abscess. Once the aspirate is localized it results in pneumonitis. Inflammatory mediators are released, morphology, resulting in the formation of colliquative necrosis. The right side lung is more commonly affected than the left. On gross morphology, the lesions are well circumscribed filled with necrotic debris and do not demonstrate well-defined borders with the surrounding lung parenchyma. Microscopic examination demonstrates neutrophilic granulocytes with dilated blood vessels and inflammatory edema.
Causes
Lung abscess is commonly caused by bacterial infections and these include bacteroides, peptostreptococcus and prevotella.