Clinical characteristics and prognostic factors of pediatric acute eosinophilic pneumonia: an 11-year single-center retrospective cohort study.

UNLABELLED: Acute eosinophilic pneumonia (AEP) is a rare, rapidly progressive respiratory disease characterized by diffuse pulmonary eosinophilia. Its etiology, clinical course, and prognosis in children remain incompletely understood. We conducted a retrospective cohort study at Yuying Children's Hospital, enrolling children diagnosed with AEP between January 2014 and December 2024. Demographic, clinical, laboratory, radiological, treatment, and outcome data were analyzed. Among 31 patients with pediatric AEP, the highest proportion occurred in autumn (38.7%). Respiratory infections were identified in 26 (83.9%) patients, most commonly Mycoplasma pneumoniae (n = 12) and human bocavirus (n = 4). Passive smoke exposure was identified in five patients (16.1%). Children with allergic comorbidities (10/31, 32.3%) demonstrated significantly elevated total immunoglobulin E levels (median, 742.0 vs. 317.5 IU/mL, P = 0.012), but otherwise comparable clinical laboratory profiles. Fifteen patients (48.4%) who presented with respiratory failure demonstrated significantly elevated procalcitonin (PCT, 0.39 vs. 0.07 µg/L, P = 0.002) and D-dimer levels (1.10 vs. 0.55 µg/mL, P = 0.015), longer hospital stays (7.0 vs. 5.0 days, P = 0.028), and a higher prevalence of pleural effusion (53.3% vs. 18.8%, P = 0.044) compared with the non-respiratory failure group. Twenty-two patients (71.0%) received systemic corticosteroids. Most achieved full recovery, though asthma (n = 5) was observed during follow-up.

CONCLUSION: Pediatric AEP is primarily infection-driven, with a probable autumn seasonality and passive smoke exposure as a potential co-trigger. Elevated PCT and D-dimer levels are associated with the development of respiratory failure. The overall prognosis is generally favorable, but long-term follow-up is essential to monitor sequelae.

WHAT IS KNOWN: •  AEP is a rare, acute hypoxemic disease characterized by eosinophil-mediated inflammation triggered by infection, inhalational exposures, or medications. •  It responds rapidly to corticosteroid therapy; pediatric-specific guidelines are lacking, and existing evidence is largely limited to case reports.

WHAT IS NEW: •  Pediatric AEP appears to be primarily infection-driven, with autumn clustering and a potential contribution from passive smoke exposure, while generally maintaining a favorable prognosis. •  Elevated PCT and D-dimer levels are associated with the development of respiratory failure in pediatric AEP.