Rare disease heralded by pulmonary manifestations: Avoiding pitfalls of an "asthma" label

Pulmonary manifestations are seldom recognized as symptoms of storage disorders. The report describes the diagnostic journey in a 30-month-old male infant, born of a third-degree consanguineous marriage referred to our institute as severe persistent asthma. History revealed that the child had progressively worsening breathlessness and persistent dry cough not associated with fever but accompanied by weight loss. On physical examination, there was growth failure, respiratory distress, clubbing, hepatosplenomegaly, and occasional rhonchi. Blood gas revealed hypoxemia which improved with oxygen administration. Plain X-rays and high-resolution computed tomography of the chest showed perihilar alveolar infiltrates and patchy consolidation. The clinicoradiological features did not support a diagnosis of asthma but favored interstitial lung disease (ILD). Bronchoalveolar lavage was performed as a first-tier investigation. It showed periodic acid-Schiff-negative foamy macrophages. The clues of consanguinity, visceromegaly, ILD, and foamy macrophages in the bronchoalveolar fluid prompted consideration of lysosomal storage disorders as the likely etiology. Gaucher disease and Niemann-Pick disease A/B were ruled out by enzyme estimation. Niemann-Pick disease type C was suspected and confirmed by detecting a homozygous mutation in the NPC2 gene. This case serves to caution physicians against labeling breathlessness in every toddler as asthma. It emphasizes the importance of searching for tell-tale signs such as clubbing and extrapulmonary clues which point to a systemic disease such as lysosomal storage disorders as a primary etiology of chronic respiratory symptoms.