Diagnostic Approach for Cavitary Lung Lesions in Children

Initial Imaging Evaluation

The American College of Radiology recommends a chest CT without IV contrast as the most appropriate initial diagnostic test for evaluating a cavitary lung lesion in a child with no prior risk factors or exposure, with thin sections (1.5 mm) to properly characterize the lesion, as CT is 10-20 times more sensitive than standard radiography for nodule/lesion characterization 1, 2
Ultrasound of the chest should be used to confirm if there is any associated pleural fluid collection, which can help differentiate between intrapulmonary and pleural pathology 3, 4
Routine lateral chest radiographs are not recommended as they rarely add additional diagnostic information beyond what is visible on the posteroanterior/anteroposterior views 3, 4

Blood cultures, including anaerobic bottle, should be obtained to identify potential infectious causes of the cavitary lesion, along with complete blood count with differential to assess for evidence of infection, inflammation, or malignancy 3, 4
C-reactive protein and erythrocyte sedimentation rate should be evaluated to assess the degree of systemic inflammation, and serum albumin levels can be low in infectious processes 3, 4

If the CT shows features suggestive of fungal infection, the European Respiratory Society recommends serum Aspergillus IgG antibody test and galactomannan antigen, and consideration of testing for other fungal pathogens such as histoplasmosis, coccidioidomycosis, and cryptococcosis 5, 6, 7
If the CT shows features concerning for tuberculosis, a tuberculin skin test and/or interferon-gamma release assay should be performed, along with early morning gastric aspirates for acid-fast bacilli (three samples) as young children rarely produce sputum 5, 6, 8

The Centers for Disease Control and Prevention recommend bronchoscopy with bronchoalveolar lavage as the diagnostic procedure of choice for obtaining samples in children with cavitary lesions, allowing for microbiological studies including bacterial, fungal, and mycobacterial cultures 8
CT-guided percutaneous needle biopsy may be considered if the lesion is peripheral and accessible, as recommended by the American College of Radiology 9

The American College of Radiology recommends employing low-dose CT technique when possible to minimize radiation exposure in pediatric patients, with doses potentially equivalent to 20-400 chest radiographs depending on the technique 1, 2, 3, 4
Chest CT scans should not be performed routinely without clear indication due to radiation concerns 3, 4