Miliary tuberculosis with diagnostic challenges in infancy: a case report from Vietnam.

BACKGROUND: Miliary tuberculosis in infants is a life-threatening condition often misdiagnosed due to non-specific symptoms that mimic common childhood illnesses such as bronchiolitis. Obtaining microbiological confirmation is challenging in paucibacillary pediatric cases, frequently delaying life-saving treatment, especially in high-burden settings such as Vietnam.

CASE PRESENTATION: We describe a case of a 3-month-old Vietnamese male infant who presented with progressive wheezing unresponsive to standard bronchiolitis therapy. Although vaccinated with Bacille Calmette-Guérin at birth, no vaccination scar was observed. Chest computed tomography revealed diffuse miliary nodules and necrotic lymphadenopathy, causing severe airway compression. While gastric aspirate samples were negative by both acid-fast bacilli smear and the Xpert Mycobacterium tuberculosis/rifampicin assay, a diagnosis was confirmed after a non-invasive nasopharyngeal swab tested positive for rifampicin-sensitive Mycobacterium tuberculosis using the same molecular assay. The patient showed rapid clinical improvement following the initiation of a 6-month anti-tuberculosis regimen.

DISCUSSION AND CONCLUSIONS: This case illustrates that miliary tuberculosis can be a critical differential diagnosis in infants with persistent wheezing. The successful use of a nasopharyngeal swab for molecular testing in this instance suggests its potential as a valuable, non-invasive diagnostic tool when traditional specimens are negative or difficult to obtain; however, its overall diagnostic yield requires evaluation in larger studies. Furthermore, the development of disseminated disease despite vaccination in an infant lacking a Bacille Calmette-Guérin scar raises questions about host immune responses and suggests a need for further research into the clinical and immunopathological significance of this finding.