[1] Cavities in the lung can be caused by infections, cancer, autoimmune conditions, trauma, congenital defects,[2] or pulmonary embolism.

[2] Symptoms of a lung cavity due to infection can include fever, chills, and cough.

[2] In the 2008 Fleischner Society "Glossary of Terms for Thoracic Imaging", a cavity is radiographically defined as “a gas-filled space, seen as a lucency or low-attenuation area, within [a] pulmonary consolidation, a mass, or a nodule”.

[3] However, a 2007 study that used CT to evaluate lung cavities showed no relationship between wall thickness and the likelihood of malignancy.

[2] Cystic bronchiectasis is irreversible bronchial dilation, which is permanent widening of the bronchioles (small airways) in the lung.

[2] It can be distinguished on imaging by a lack of bronchial tapering, meaning that the bronchioles do not get narrower as they travel further into the lung.

Cystic bronchiectasis is also associated with an increased bronchoarterial ratio, meaning that the bronchioles are larger than the blood vessels that run alongside them.

[7] The most common bacterial causes of lung cavities are Streptococcus species and Klebsiella pneumoniae.

[5] Less commonly, the bacteria Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter, Escherichia coli, and Legionella can cause cavitation.

[5] 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.

[5] Melioidosis, caused by the bacteria Burkholderia pseudomallei, is common in tropical areas, especially Southeast Asia, and is frequently associated with lung cavities.

[4] 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),[7] older age, diabetes mellitus, drug abuse, and artificial ventilation.

[8] Even after successful treatment with anti-tuberculosis drugs, 20-50% of patients with cavitary tuberculosis have persistent cavities, which results in decreased lung function and increased risk of opportunistic infections by Aspergillus fumigatus and other fungal pathogens.

[10] Mycobacterium avium complex (MAC) is the most common cause of NTM lung disease in most countries, including the United States.

[6] Fungal infections that can cause cavitations include histoplasmosis, coccidioidomycosis, cryptococcosis, and aspergillosis.

[2] An aspergilloma is an infection of a pre-existing lung cavity by Aspergillus species without tissue invasion and results in the formation of a fungal ball.

[4] Risk factors for chronic necrotizing aspergillosis include advanced age, alcoholism, diabetes, and mild immunosuppression.

This results in cysts forming in the body, most commonly in the liver, but lung involvement is seen in 10-30% of cases.

[7] Paragonimus westermani, also called the lung fluke, is a flatworm which is transmitted by eating freshwater crabs or crayfish containing metacercaria (the infective form of the tapeworm).

[2] Other primary cancers of the lung, such as lymphoma and Kaposi’s sarcoma, can also cavitate, especially in people with AIDS.

[4] Ankylosing spondylitis, eosinophilic granulomatosis with polyangiitis, and systemic lupus erythematous rarely cause lung cavities.

[4] Risk factors for septic pulmonary emboli include IV drug use, implanted prosthetic devices (like central lines, pacemakers, and right-sided heart valves), and septic thrombophlebitis (a blood clot in a vein due to infection).

[2] These congenital lesions are the most common cause of lung cavities in infants, children, and young adults.