Abstract: Objective To explore the clinical characteristics, diagnosis and treatment of Mycoplasma pneumoniae pneumonia (MPP)complicated with cardiac thrombus and pulmonary embolism in children. Methods The clinical data of MPP complicated with cardiac thrombus and pulmonary embolism in a child were retrospectively analyzed, and the cases of MPP complicated with cardiac thrombus and pulmonary embolism in CNKI, Wanfang database and PubMed were searched and analyzed. Results A 4 -year-old boy presented with fever and cough; his serum Mycoplasma pneumoniae (MP) antibody titer was higher than 1 : 1280 , and D-dimer was significantly increased. CT showed a large area of inflammatory consolidation in the left lung, and echocardiography showed a mass in the right ventricular cavity. The patient received combined treatment of right ventricle tumor extraction, bronchoscopic lavage and anti-infection, and pulmonary inflammation was improved for a time. Subsequently, the child's condition worsened, and chest enhanced CT showed left lower pulmonary embolism. After anticoagulant therapy, pulmonary inflammation and pulmonary embolism were improved. The postoperative pathology of the right ventricle mass of the child showed inflammatory necrotic tissue. The child was finally diagnosed of MPP with intracardiac thrombosis and pulmonary embolism. Four cases of MPP complicated with intracardiac thrombosis were reported in domestic and foreign literatures, and all of them were boys aged from 4 to 9 years old. Intracardiac thrombosis was found in 3 children 4 - 11 days after onset, 4 children had positive anti-cardiolipin antibody, 2 had elevated D-dimer, 2 underwent surgery, and 2 received anticoagulation therapy. All children were cured and anti-cardiolipin antibodies turned negative at 3 months of followup. Conclusions When MP infection causes lobar pneumonia or pleural effusion, D-dimer levels and anticardiolipin antibodies should be dynamically monitored and so embolism or thrombosis can be timely detected. Early diagnosis and timely treatment will lead to a good prognosis.

Key words: Mycoplasma pneumoniae pneumonia; cardiac thrombus; pulmonary embolism