Imaging of pediatric pulmonary infections: A pictorial review

Table 1 Imaging features and distinguishing characteristics of common pediatric pulmonary infections

Pathogen	Clinical context	Common imaging findings (CXR/CT)	Distinguishing features/complications
Respiratory syncytial virus	Infants and young children, especially with chronic lung disease or prematurity	Peribronchial thickening, hyperinflation, patchy atelectasis	Most common LRTI in infants; indistinct from other viruses on CXR
Human metapneumovirus	Similar to RSV; affects children < 5 years	Same as RSV: Hyperinflation, atelectasis, perihilar opacities	Often milder than RSV; supportive care is mainstay
Parainfluenza virus	Children with croup or LRTI	Subglottic narrowing (“steeple sign”), perihilar opacities, atelectasis	Croup presentation (stridor, barking cough); lower tract infection < 10%
Adenovirus	Infants, toddlers; post-infectious bronchiolitis obliterans risk	Patchy opacities, hyperinflation, air trapping (CT: Mosaic attenuation)	Chronic sequelae: Constrictive bronchiolitis; often severe disease
Influenza (H1N1, B)	All ages; epidemics	Bilateral infiltrates, ground-glass opacities, lobar consolidation (CT)	Severe in immunocompromised; overlap with bacterial superinfection
Streptococcus pneumoniae	Most common bacterial cause < 5 years	Lobar consolidation, air bronchograms	Risk of pleural effusion, empyema, necrosis in severe cases
Staphylococcus aureus	Hematogenous spread, post-viral pneumonia	Patchy/multifocal infiltrates, pneumatoceles, abscesses	High complication risk: Necrotizing pneumonia, empyema
Klebsiella pneumoniae	Immunocompromised, aspiration	Bulky consolidation, abscesses with air-fluid levels	Can mimic TB; necrosis common
Mycoplasma pneumoniae	School-aged children, adolescents	Segmental/Lobar consolidation, interstitial infiltrates (GGO, septal thickening)	Often subacute; extrapulmonary manifestations possible
Primary TB	Children < 5 years; endemic areas	Hilar/mediastinal lymphadenopathy ± mild parenchymal opacities	May cause bronchial obstruction; CT better for lymph nodes
Miliary TB	Infants, immunocompromised	Countless tiny nodules throughout lungs	Hematogenous spread; high mortality if untreated
Post-primary TB	Adolescents or reactivation cases	Upper lobe cavitation, tree-in-bud nodules, consolidation	Spinal involvement (Pott’s disease), paraspinal abscess
Aspergillus (fungus ball)	Pre-existing cavity, immunocompetent	Mobile intracavitary mass, air-crescent sign	Changes with position; typically non-invasive
Allergic bronchopulmonary aspergillosis	Asthma, CF	Central bronchiectasis, mucus plugging (“finger-in-glove”)	IgE elevation, eosinophilia, recurrent exacerbations
Invasive aspergillosis	Immunocompromised (BMT, neutropenia)	Nodules with halo sign, cavitation, pneumomediastinum	Angio-invasive: Infarction; airway-invasive: Air leaks, CT essential

CXR: Chest X-ray; CT: Computed tomography; RSV: Respiratory syncytial virus; hMPV: Human metapneumovirus; LRTI: Lower respiratory tract infection; H1N1: Hemagglutinin type 1 and neuraminidase type 1 (Influenza A subtype); GGO: Ground-glass opacity; TB: Tuberculosis; CF: Cystic fibrosis; BMT: Bone marrow transplant.