Pulmonary embolism and septic emboli
Pulmonary embolism (a blood clot in the lung) causes pulmonary infarction (the death of lung tissue) less than 15% of the time, and only about 5% of pulmonary infarctions result in lung cavities. Septic pulmonary emboli (infected blood clots) are collections of infectious organisms, fibrin, and platelets that travel through the blood to the lung and cause small areas of pulmonary infarction by blocking off blood flow. This results in multiple small cavities 85% of the time. Symptoms can include cough, dyspnea (shortness of breath), chest pain, hemoptysis (coughing up blood) and sinus tachycardia (a fast heart rate). 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). Two forms of septic thrombophlebitis include pelvic thrombophlebitis and Lemierres syndrome (septic thrombophlebitis of the internal jugular vein). Trauma
Pulmonary contusion (lung bruise) from blunt chest trauma causes bleeding into the alveoli (air sacs) and can cause small cavities to form that are called traumatic pulmonary pseudocysts (TPP). This is rare, as less than 3% of lung injuries lead to TPP. It can occur at any age, but is more common in children and adults under the age of 30. Although it can occur anywhere in the lung, it is most common in the lower lobes. TPP usually resolves on its own within four weeks.
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.