Clinical, Bronchoscopic and BALF Cytological Characteristics in Children with Chlamydia pneumoniae Pneumonia Undergoing Clinically Indicated Bronchoscopy: A 10-Year Single-Center Retrospective Analysis

Background: Chlamydia pneumoniae is a recognized cause of pediatric community-acquired pneumonia, but its bronchoscopic features and bronchoalveolar lavage fluid (BALF) cytology remain poorly characterized. While our previous single-center study outlined the broad epidemiological and clinical-radiological profiles of hospitalized children with Chlamydia pneumoniae pneumonia (CPP), it did not specifically evaluate the subgroup undergoing invasive bronchoscopy. This exploratory cohort study aimed to comprehensively characterize the clinical manifestations, bronchoscopic features, and BALF cytological profiles of hospitalized children with CPP who underwent clinically indicated flexible bronchoscopy. Methods: We retrospectively identified 61 hospitalized children with PCR-confirmed CPP who underwent clinically indicated flexible bronchoscopy with bronchoalveolar lavage (BAL) at Hebei Children’s Hospital (May 2015–May 2025). Clinical data, bronchoscopic findings, BALF cytology, and chest CT findings were analyzed. Results: The cohort (mean age: 10.3 years; 73.8% male) predominantly presented with cough (98.36%) and fever (54.10%). Bronchoscopy consistently revealed mucosal hyperemia and edema, longitudinal mucosal folding, and flocculent exudates across all or most examined airways. BALF cytology showed marked neutrophil predominance (median: 79.0%, IQR: 76.0–82.0%). Chest CT identified consolidation or atelectasis in 72.1% of cases. Bronchoscopic examination demonstrated that lingular and basal segments were the most frequently affected airway regions, with a mean of 4.6 involved segments per patient (range: 2–10). A moderately positive correlation was observed between BALF and peripheral blood neutrophil percentages, whereas the correlation for lymphocytes was non-significant; neither association remained significant after FDR correction for multiple testing. Conclusions: These findings solely reflect characteristics of patients meeting procedural indications and stem from a non-generalizable retrospective cohort; thus, they should not be extrapolated to the broader pediatric CPP population. Firm conclusions regarding diagnostic utility, anatomical mechanisms, or therapeutic efficacy cannot be drawn from this dataset. Future prospective, multi-center cohort studies are warranted to validate these exploratory observations.