Nocardia is a bacterium that can cause pulmonary nocardiosis and lung cavities in people who are immunocompromised (have weak immune systems), including organ transplant recipients who are on immunosuppressants, and those with AIDS, lymphoma, or leukemia. Melioidosis, caused by the bacteria Burkholderia pseudomallei, is common in tropical areas, especially Southeast Asia, and is frequently associated with lung cavities.Pneumonia can lead to the development of a lung abscess, which is a pus-containing necrotic lesion of the lung parenchyma (lung tissue). On CT scan of the chest, a lung abscess appears as an intermediate- or thick-walled cavity with or without an air-fluid level (a flat line separating the air in the cavity from the fluid). An abscess can occur anywhere in the lung. Risk factors for polymicrobial lung abscesses (abscesses caused by multiple species of bacteria) include alcoholism, a history of aspiration (food or water accidentally going down the trachea), poor dentition (bad teeth), older age, diabetes mellitus, drug abuse, and artificial ventilation. Polymicrobial lung abscesses are usually due to aspiration and are located in the posterior segments of the upper lobes or superior segments of the lower lobes. Klebsiella pneumoniae is a common cause of lung abscesses and is usually monomicrobial (caused by a single species of bacteria). Risk factors include diabetes and chronic lung disease. A lung abscess due to Klebsiella can progress to massive pulmonary gangrene, a rare condition in which an entire section of the lung is completely destroyed. Half of all cases of pulmonary gangrene are caused by Klebsiella.
11% of primary lung cancers (cancers that start in the lung) have cavities that can be seen on chest X-ray; 22% of primary lung cancers will have cavities on CT, which is more sensitive. Squamous-cell carcinoma of the lung is more likely to develop cavitations than lung adenocarcinoma or large-cell lung carcinoma. Other primary cancers of the lung, such as lymphoma and Kaposi’s sarcoma, can also cavitate, especially in people with AIDS. Lung cancers that develop cavities are associated with a poor prognosis (worse outcomes). Cancers that metastasize (spread) to the lung can also develop cavitations, but this is only seen about 4% of the time on X-ray. Metastatic cancers of squamous cell origin are also more likely to cavitate than cancers of other origins. Both chemotherapy (drugs to treat cancer) and radiofrequency ablation (destroying cancer with radio waves) can cause lung cancers to develop cavities, which is a sign of a good response to treatment. It is possible to have both an infection and lung cancer in the same cavity; the most common combination is primary lung cancer and tuberculosis. Autoimmune
Autoimmune causes of lung cavities include granulomatosis with polyangiitis, rheumatoid arthritis, and rarely necrotizing sarcoidosis (less than 1% of people with sarcoidosis develop lung cavities). Ankylosing spondylitis, eosinophilic granulomatosis with polyangiitis, and systemic lupus erythematous rarely cause lung cavities.