Table 3 Systematic approach to the diagnosis of intrathoracic TB in children

Step 1: Identify findings suggestive of TB disease

• Clinical evaluation: history & physical exam

• Radiological imaging: chest radiography; computed tomography; ultrasonography

• Laboratory studies: composite measures (cell count and chemistry) of body fluids (e.g., pleural fluid)

• Endoscopic studies: bronchoscopy

Step 2: Identifying findings supportive of TB as the etiology

• TB exposure history

• Immune-based tests: TST; IGRA

• Biochemical markers: ADA in body fluids (e.g., pleural fluid; pericardial fluid)

• Mycobacterial detection: smear microscopy; NAAT; culture; antigen test (in HIV-infected adolescents, lateral flow lipoarabinomannan in urine with CD4 < 100)

• Histopathological & cytopathological studies

• Excluding other differential diagnoses

Step 3: Screen for risk factors for progression to TB disease

• Age groups (e.g. immunological immaturity of infancy)

• Immunocompromising conditions (e.g., HIV infection)

• Immunosuppressive medications (e.g., TNF-α) antagonists

• Contained TB infection-disease (e.g., noncalcified fibronodular lesions, especially apical, on chest imaging

• Environment (e.g., continued exposure)

Step 4: Follow-up evaluation to support or exclude TB as the etiology