Pulmonary Alveolar Proteinosis in an Infant with ADA-Deficient SCID

Adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) is a rare disorder characterized by profound lymphocytopenia, recurrent infections, and non-infectious complications such as pulmonary alveolar proteinosis (PAP). PAP in ADA-SCID results from impaired surfactant clearance due to dysfunctional alveolar macrophages and may cause hypoxemia, chronic pulmonary complications and death if treatment is delayed. This case describes a 3-week-old female diagnosed with ADA-SCID, who developed acute hypoxic respiratory failure secondary to PAP confirmed by positive Periodic Acid-Schiff staining of bronchoalveolar lavage and diffuse ground glass opacities on chest CT. The child was treated with enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT) and demonstrated normalization of physical exam, oxygen saturation and chest imaging. This case illustrates the importance of early recognition and definitive therapy for ADA-SCID-associated PAP including ERT and HSCT, rather than traditional and high-risk interventions for pediatric PAP including whole lung lavage. Timely intervention can lead to favorable pulmonary outcomes.