Incidence, clinical features and risk factors of interstitial pneumonia in children with acute lymphoblastic leukemia.

Interstitial pneumonia (IP) is an important pulmonary complication in children with acute lymphoblastic leukemia (ALL), yet its incidence, clinical characteristics, and predictors remain insufficiently defined. We conducted a single-center retrospective study including 484 children diagnosed with ALL and treated at the First Affiliated Hospital of Sun Yat-sen University between February 2002 and January 2022. Among 484 patients, 33 (6.82%) developed IP. The incidence was higher in boys than girls (8.92% vs. 2.94%) and significantly elevated in high-risk versus non–high-risk ALL (16.67% vs. 3.78%,  < 0.001). IP occurred more frequently during maintenance therapy than intensive chemotherapy (75.75% vs. 24.25%,  = 0.047), with a median onset of 122 days after maintenance initiation. Common symptoms included dyspnea (100%), fever (87.87%), and cough (75.75%). Imaging commonly demonstrated diffuse ground-glass opacities and interstitial changes. Management involved antibacterial therapy (84.84%), antifungals (75.75%), antivirals (72.72%), corticosteroids (87.87%), and oxygen therapy (93.93%). Twenty-six patients improved, whereas seven died, predominantly due to respiratory failure. In high-risk patients during maintenance therapy, lower absolute lymphocyte counts and changes in absolute neutrophil count/white blood cell ratio (ANC/WBC) and absolute lymphocyte count/white blood cell ratio (ALC/WBC) were significantly associated with IP onset, suggesting their potential predictive value. No variables were significantly associated with mortality. Early recognition and timely initiation of corticosteroids and supportive care are essential. Hematologic indices may help identify children at heightened risk, supporting improved surveillance and risk-adapted management.