What are typical examples of chest x-rays (CXR) characteristic of tuberculosis (TB)?

Characteristic Chest X-ray Findings in Tuberculosis

Chest radiography is the first-line imaging modality for diagnosing tuberculosis, with typical findings including upper lobe infiltrates, cavitation, and fibro-cavitary disease in the apical and posterior segments of the upper lobes or superior segments of the lower lobes. 1

Primary Radiographic Patterns

• Primary TB typically presents with lobar pneumonia with hilar and/or mediastinal adenopathy, more commonly seen in children and severely immunocompromised individuals 1
• Postprimary/Reactivation TB typically shows apical posterior upper lobe or superior segment lower lobe fibro-cavitary disease with endobronchial spread through airways 1, 2
• Cavitation is the hallmark of postprimary tuberculosis, appearing in approximately 45% of patients 2, 3
• Patchy, poorly defined consolidation in the apical and posterior segments of the upper lobes is commonly observed (91% of cases) 2, 3

Key Radiographic Features

• Upper lobe involvement is seen in 92% of adult pulmonary TB cases in developed countries 4
• Cavitation is highly correlated with smear positivity (89% of cavitary cases are positive by microscopy) 4
• Infiltrates can be patchy or nodular in appearance 1
• Pleural effusion is seen in approximately 18-24% of cases 2, 3
• Miliary pattern (disseminated disease) appears as numerous small nodules throughout both lungs, seen in approximately 6% of cases 2

Atypical Presentations

• Unusual radiographic patterns occur in approximately 8% of adult pulmonary TB cases 4, including:

  • Isolated lower lobe infiltrations
  • Hilar adenopathy without parenchymal involvement
  • Miliary TB
  • Tuberculoma (mass-like lesion)
  • Normal chest X-ray (seen in approximately 3% of cases) 2, 4

• HIV-infected patients commonly show atypical presentations:

  • Less frequent apical cavitary disease
  • More common infiltrates in any lung zone
  • More frequent mediastinal or hilar adenopathy 1

Advanced Imaging Considerations

• CT should be considered when:

  • Chest X-ray is equivocal
  • Patient is immunocompromised, particularly with low CD4 counts
  • Classic findings are not present on chest X-ray 1

• CT increases diagnostic specificity by better showing:

  • Cavitation
  • Endobronchial spread with tree-in-bud nodules
  • Early disease not visible on plain radiographs 1

Common Diagnostic Pitfalls

• Failure to recognize hilar and mediastinal lymphadenopathy as a manifestation of primary TB in adults 2
• Exclusion of TB because disease predominates in or is limited to the anterior segment of an upper lobe or basilar segment of a lower lobe 2
• Overlooking minimal fibroproductive lesions or reporting them as inactive 2
• Failure to recognize that an upper-lobe mass surrounded by satellite fibroproductive lesions might be tuberculous 2

Emerging Technologies

• Deep learning algorithms for TB detection using chest X-rays have shown promising results with reported accuracy of 94%, sensitivity of 96.85%, and specificity of 91.49% 5
• Machine learning approaches may help overcome limitations of human reading of chest radiographs, which can have substantial within- and between-observer variability 6

Clinical Correlations

• Extensive lesions on X-ray are associated with high glycosylated hemoglobin levels 7
• Cavitation is associated with multidrug-resistant TB 7
• Bilateral cavities are strongly associated with multidrug-resistant TB 7
• Poor treatment outcomes show borderline significance with extensive lesions at onset 7