Abstract: Objective The clinical manifestations and imaging features of mycoplasma pneumoniae pneumonia in children were retrospectively analyzed to provide basis for clinical diagnosis and treatment. Method The general clinical data, chest CT imaging data and etiological examination results of 200 outpatients and inpatients with mycoplasma pnuemoniae pneumonia in the First Hospital of Tsinghua University and the Children's Hospital Affiliated to Capital Institute of Pediatrics from November 2023 to January 2024 were retrospectively analyzed. Chest CT imaging indicators included the distribution of lesions in the lung, thickening of the bronchial wall, imaging manifestations of lesions in the lung, presence or absence of plastic bronchitis, presence or absence of pleural effusion,etc. Result A total of 200 children with mycoplasma pneumoniae pneumonia were included, ranging from 1 month to 15 years old, with an average age of (8.29±2.81) years, including 107 boys (53.5%) and 93 girls(46.5%). The main clinical symptom was fever in 165 cases (66.0%). The duration of fever ranged from 1 to 30 days, with a median of 7 days. Followed by 162 cases of cough (64.8%), the duration of cough ranged from 2 to 60 days, with a median of 10 days days. Other symptoms in order of frequency were expectoration, wheezing, runny nose, sore throat, vomiting, headache, chest pain, dyspnea, urticaria, etc. The most involved lung lesions were left inferior lobe, followed by right inferior lobe. The most common imaging findings were bronchial wall thickening, tree-in-bud sign, and consolidation. Mycoplasma pneumoniae pneumonia in children with adenovirus infection is the most common. The children with plastic bronchitis and non-plastic bronchitis had statistically significant differences in respiratory syncytial virus infection, tree-in-bud sign, acinar nodules, consolidation, atelectasis and pleural exudation. Conclusion The main clinical manifestations of mycoplasma pneumoniae pneumonia in children are fever and cough. Thickening of bronchial wall, tree-in-bud sign, tree-in-fog sign, and mass consolidation are the most common characteristic imaging manifestations. The presence of plastic bronchitis should be considered when the pulmonary imaging of children with mycoplasma pneumoniae pneumonia shows acinar nodules, consolidation, atelectasis and pleural exudation.

Key words: Mycoplasma pneumoniae, Pneumonia, Computed tomography, Tree-in-fog sign, Plastic bronchitis