Lung ultrasound and the interstitial syndrome in tuberculosis endemic regions: illustrated insights from diverse clinical settings

Lung ultrasound (LUS) is increasingly used as a diagnostic tool in respiratory medicine, particularly in resource-limited, tuberculosis (TB)-endemic settings. Sonographic interstitial syndrome (IS), characterized by B-line artefacts, has proven valuable in diagnosing cardiogenic pulmonary edema, pneumonia, and chronic interstitial lung disease. However, in TB-endemic areas, its interpretation remains challenging due to overlapping pathologies. This illustrated review explores the diagnostic and prognostic relevance of IS across three clinical contexts: acute respiratory distress, chronic interstitial lung disease, and pulmonary TB. We review current evidence and discuss illustrative cases from TB-endemic settings to highlight sonographic pattern variations and guide clinicians in recognizing key diagnostic features and common pitfalls. IS, while inherently non-specific, gains diagnostic value when contextualized within the patient's background and within additional sonographic findings such as pleural line abnormalities, consolidations, and altered lung sliding. Specific TB manifestations—including miliary TB, cavitary TB, HIV-associated TB, and post-TB sequelae—demonstrate diverse IS presentations. Accurate interpretation requires understanding disease-specific patterns, using appropriate scanning techniques, and adhering to standardized protocols. Greater awareness of IS variations among clinicians can improve diagnostic accuracy and clinical decision-making in TB-endemic regions.