Chest pain consisting of either a dull ache or a true pleurisy is common. Most patients have fever, but frank rigors are unusual. In patients with a chronic course lasting many weeks, anorexia, weight loss, and debility are often seen. These findings are not diagnostic, however, and chest x-rays or CT scans are required to establish the presence of an abscess. Chest CT scans can define the extent of the abscess and, on occasion, may reveal an abscess not apparent on chest x-ray.
Abscesses occur more often in the right lung than in the left lung.
Although any lung segment may be involved, abscesses are most common in the posterior segments of the upper lobes and the apical segments of the lower lobes because these areas are dependent when the patient is recumbent. Abscesses may be single or, less often, multiple. Although primary lung abscesses begin with necrotizing pneumonitis, cavitation is radiographically evident in most patients by the time lung abscess is diagnosed. The finding of air-fluid levels signifies rupture into the bronchial tree. As is the case with other pulmonary infections, examination of the sputum is crucial to diagnosis.