<i>Mycoplasma pneumoniae</i> Pneumonia With Multiple Thromboses and Airway Stenosis: A Case Report

A 12-year-old boy was admitted to a local hospital with a fever and cough. An etiological examination suggested a Mycoplasma pneumoniae (MP) infection. Unexpectedly, he abruptly experienced facial paralysis, limb movement disorder, and epileptic seizures on the 6th day of the course, and computed tomography (CT) revealed cerebellar infarctions. He was treated with sedation and tracheal intubation and was then transferred to the Children's Hospital of Nanjing Medical University. The child was hospitalized three times. His major symptoms and imaging results are shown in Figure 1, and his laboratory examination results are shown in Table 1. Radiological examination revealed lobar pneumonia (Figure 1A) and cerebral infarctions (Figure 1B) with thromboses in the left lower pulmonary artery (Figure 1C), left vertebral artery (Figure 1D), and right posterior cerebral artery (Figure 1E). Suspected splenomegaly was also observed (Figure 1F), and after multidrug treatment and two rounds of fiberoptic bronchoscopy with bronchoalveolar lavage, his clinical manifestations and cerebral imaging findings improved. His chest and abdominal examination findings worsened, and necrotizing pneumonia in the lower right lung (Figure 1G) and multiple splenic infarctions (Figure 1H) were observed. Additionally, his second fiberoptic bronchoscopy with bronchoalveolar lavage revealed slight narrowing of the central airway and bloody bronchial casts in the lumen of the left lower lobe bronchus. Considering that he had no positive signs or symptoms, he was discharged on Day 55 of the course. However, he was readmitted because of severe dyspnea on Day 82 of the course. CT (Figure 1I,J, see original images for high resolution images) confirmed obvious stenosis in the middle section of the trachea, indicating central airway stenosis. Flexible bronchoscopy with balloon dilation revealed a scar-like stenosis ~4 cm in length and located 15 cm from the incisors, with the narrowest part measuring 3–4 mm in diameter. His dyspnea significantly improved 4 days after tracheal intubation; however, he experienced epileptic seizures again, and sedative and antiepileptic drugs were administered. Ultimately, the patient was discharged in a stable condition on Day 100 of the course, following nebulization, rehabilitation, and hyperbaric oxygen therapy. MP pneumonia (MPP) became a global pandemic in the autumn of 2023, with an increasing incidence of complications [1]. Thrombosis is a common complication of MPP and its clinical manifestations vary greatly depending on the specific systems affected [2]. In addition, small airway lesions such as bronchitis obliterans and bronchiolitis obliterans often lead to dyspnea or even respiratory failure [3], while central airway stenosis is rarely reported. This case was notable for the early onset of neurological impairment. Radiological examinations and fiberoptic bronchoscopy revealed cerebral, pulmonary, and splenic infarctions, and laboratory examinations indicated an abnormal coagulation status. Considering that the patient was beyond the temporal window for thrombolysis when transferred to our hospital, we adopted anticoagulation and intracranial pressure control therapies; early rehabilitation interventions were beneficial. The currently recognized pathogenesis of thrombosis after MP infection includes direct invasion, immune-mediated lesions, and hypercoagulable states [4]. Endothelial cell damage, whether through direct invasion or indirect invasion, leads to platelet accumulation and activates endogenous and exogenous clotting pathways. The interplay between coagulation, anticoagulation, and fibrinolysis results in a hypercoagulable state, followed by continuous thrombosis promotion, vascular stenosis, occlusion, and even organ ischemia or infarction. Fibrinogen degradation products (FDPs) and D-dimer are widely used indicators of MPP. Additionally, hematological disorders can increase thrombosis risk, so when it comes to children with recurrent or multiple thromboses, as observed in our patient, comprehensive coagulation function tests should be conducted, including platelet function tests, coagulation factor assays, anticoagulant system defect screenings, and antiphospholipid antibody evaluations. Treatment strategies include thrombus recanalization, anticoagulation, and functional protection therapies, which reduce the risk of irreversible brain injury. Enhanced nursing care and early rehabilitation were emphasized. Remarkably, this child also developed central airway stenosis, which is rare. Mild narrowing of the main airway was observed at ~6 weeks, with a progressive worsening of wheezing. At ~12 weeks, he experienced dyspnea, with CT reconstruction and fiberoptic bronchoscopy confirming central airway stenosis, and balloon dilation was performed to expand the narrowed airway. While small airway lesions, such as bronchitis obliterans and bronchiolitis obliterans, are recognized as long-term concurrent diseases of MPP, often resulting in ventilation dysfunction [5], few researchers have investigated the relationship between central airway lesions and MPP. Irreversible respiratory tract stenosis caused by scar formation after persistent inflammation may be a possible pathogenic mechanism; however, further research is required to determine how MP causes central airway stenosis. In patients with airway stenosis, early interventional strategies, such as tracheal stenosis dilation, can improve prognosis, and some patients need to be treated with endotracheal stenting, open surgery, or even tracheal transplantation. In conclusion, MPP is often accompanied by pulmonary and extrapulmonary complications that may occur independently or simultaneously. Clinicians should be vigilant about potential complications, such as thrombosis or airway stenosis, especially in patients who present with unusual symptoms that indicate organ infarction or failure. Early diagnosis and appropriate treatment are crucial for optimizing patient outcomes. Rui Zhang: visualization, writing – original draft. Feng Liu: conceptualization, writing – review and editing. All authors read and approved the final manuscript. The authors received no specific funding for this work. The study involving human participants was approved by the Ethics Committee of Children's Hospital of Nanjing Medical University (Approval Number: 202408039-1). This study received an exemption from informed consent, because we only used medical records obtained in previous clinical care, and we did not disclose any information that may reveal the identity of the patient. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors have nothing to report. All relevant data are within the manuscript.