Abscess formation is uncommon in pneumococcal pneumonia. In other patients, abscess develops as a result of bronchial obstruction caused by tumors, foreign bodies, or bronchial stenosis. Septic pulmonary embolization is a cause of abscess formation. Pulmonary tuberculosis, fungal infection, or actinomycosis often leads to cavity formation. In the immunosuppressed host, Nocardia and other opportunistic organisms may also produce cavitation.
Noninfectious processes can produce cavitary lung lesions.
The clinical presentation of the patient with a lung abscess depends on the type of abscess. Patients with abscesses resulting from necrotizing staphylococcal or gram-negative bacillary pneumonias are usually acutely ill and exhibit clinical features of the underlying pneumonia. Although patients with primary lung abscess may also present acutely with aspiration pneumonia, they more often experience insidiously progressive symptoms for weeks or even months before diagnosis. Hemoptysis is present in approximately one third of cases and may occasionally reach life-threatening proportions. Chest pain consisting of either a dull ache or a true pleurisy is common.