Hypersensitive Pneumonitis: an Initial Presentation of Chronic Granulomatous Disease in a Child.

Hypersensitive pneumonitis (HP) is a rare initial presentation of chronic granulomatous disease (CGD), especially in children. CGD presenting as HP may result from exposure to inhaled environmental antigens and be induced by excessive production of inflammatory cytokines due to loss of reactive oxygen species production. We herein describe a 2-year-old boy with CGD caused by a mutation in CYBB gene, who initially presented with HP. The patient developed dry cough, progressive dyspnea, and fever after playing in dusty air in a factory that produced plastic materials containing isocyanates. The patient's symptoms and radiological abnormalities did not improve after antigen avoidance, but disappeared after corticosteroid therapy. Because HP is uncommon in children, we should consider the possibility of CGD in children who present with HP. A prompt diagnosis of CGD is essential to enable initiation of prophylactic antibacterial and antifungal therapies.