Features | Examples | |
Bleb | Previously, "bleb" referred to a rounded, subpleural lucency, <1 cm diameter. Now considered to be a type of bulla, and use of the term is discouraged. | |
Bulla | Rounded, focal, thin-walled (<1 mm); usually several centimeters in diameter, can fill hemithorax, can be seen in association with emphysema. | Emphysema. |
Bronchiectasis | Dilated, thick-walled bronchi can look cystic, but are in communication with airway; may be clustered. | Cystic fibrosis, primary ciliary dysfunction, common variable immunodeficiency, postinfectious. |
Cavity | Thick walled (>4 mm) may be partially filled with fluid, debris, mycetoma. Can be within a mass, nodule, or area of consolidation. | Necrotizing bacterial pneumonia, mycobacterial or fungal infection, neoplasm (eg, bronchogenic carcinoma if single; metastatic cancer if multiple), granulomatosis with polyangiitis (GPA) and other vasculitides. |
Cyst | Round or irregular, variable size, thin-walled (<2 mm thick), may be associated with nodules. | Birt-Hogg-Dubé syndrome, lymphangioleiomyomatosis, lymphocytic interstitial pneumonia, pulmonary Langerhans cell histiocytosis. |
Emphysema | Rounded or polygonal lucencies without walls; variable size. Paraseptal emphysema is bounded by pleura and interlobular septa; centrilobular emphysema has an upper lobe predilection. | Alpha-1 antitrypsin deficiency, lung injury due to cigarette smoking or indoor cooking fires. |
Honeycombing | Clusters of round, 3 to 10 mm diameter lucencies, wall-thickness 1 to 3 mm; may be multitiered, typically in a subpleural location, associated with traction bronchiectasis and septal thickening. | Asbestosis, idiopathic pulmonary fibrosis (IPF), usual interstitial pneumonia in systemic rheumatic disease, chronic hypersensitivity pneumonitis. |
Pneumatocele | Often postinfectious, may be solitary or multiple, typically transient. | Postinfectious (eg, Staphylococcus aureus pneumonia, Pneumocystis jirovecii pneumonia, coccidioidomycosis), post-traumatic, hydrocarbon inhalation. |
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