Type:
Educational Exhibit
Keywords:
Parasites, Infection, Cavitation, Socio-economic issues, Education, Complications, CT-High Resolution, CT, Conventional radiography, Thorax, Respiratory system, Lung, Chest, Not applicable
Authors:
B. D. Norena Rengifo1, A. Arroyave2, A. T. suarez2; 1Medellin, Antioquia/CO, 2Medellin/CO
DOI:
10.26044/ecr2020/C-10945
Background
Fleischner Society define a cavity as a gas-filled space, observed as a lucent or low-attenuation area within a mass, nodule or consolidation with a defined wall > 4mm thick.
Cavities are frequently found on thoracic images and they have many differential diagnoses including infections, autoimmune disorders and neoplasms(primary and metastatic).
Pathological processes of a cavity including caseous necrosis as in tuberculosis, cystic dilatation of lung structures as in Pneumocystis pneumonia, suppurative necrosis as in pyogenic lung abscess, or displacement of lung tissue by cystic structures as in Echinococcus.
Although in Colombia Tuberculous Mycobacterium is the most common cavitary lung infection (Fig 1), there are other infections less common but very important in the differential diagnosis.
An adequate approach to evaluate a cavitary lung infection is firstly to identify a true cavity and excluding mimics (cysts, emphysema, infected bullae and cystic bronchiectasis), then it is possible to categorize them according to the duration of clinical symptoms and chest imaging findings in acute and subacute those < 12 weeks old suggesting common bacterial and uncommon nocardial and fungal causes of pulmonary abscesses, necrotizing pneumonias and septic emboli, and chronic cavities those > 12 weeks old suggesting mycobacterial, fungal, viral, or parasitic infections. Subacute and chronic pulmonary infections are more associated with cavities than acute infections, except by the necrotizing pneumonias due to Staphylococcus aureus and K. pneumoniae (Fig 2).
Some chest imaging findings suggest a particular diagnosis such as multiple peripheral nodules in varying stages of cavitation associated with septic emboli, halo and reversed halo signs suggesting fungal infections and septic emboli, or bronchiectasis associated with peripheral small airways disease indicating widespread chronic disease.
The lack of specificity in radiographic findings requires that imaging features be combined with clinical context to make an adequate diagnosis.