Hereditary pulmonary alveolar proteinosis in a 5-year-old child: Diagnostic insights and therapeutic approach.

Hereditary pulmonary alveolar proteinosis (hPAP) is a rare disorder caused by mutations in the CSF2RA or CSF2RB genes, leading to impaired surfactant clearance by alveolar macrophages and subsequent respiratory dysfunction. A 5-year-old female with a 2-year history of poor weight gain, fatigue, and intermittent fever was evaluated. Clinical evaluation revealed hypoxemia, while high-resolution computed tomography (HRCT) of the chest showed the characteristic "crazy-paving" pattern suggestive of PAP. Bronchoalveolar lavage (BAL) yielded milky fluid with periodic acid-Schiff (PAS)-positive material, and genetic testing confirmed a homozygous mutation in the CSF2RA gene, consistent with hPAP. The patient underwent therapeutic whole lung lavage (WLL), resulting in significant clinical improvement. This case underscores the challenges of diagnosing pediatric hPAP and the value of integrating imaging, pathology, and genetic testing. While WLL remains the mainstay of treatment, further research is needed to develop targeted therapies.