Abstract
Thrombosis is uncommon but increasingly recognized complication in pediatric patients with Mycoplasma pneumoniae (M. pneumoniae) infection. In general, small-vessel thrombosis is treated by medication therapy. However, the management of thrombosis in large vessels is more complex and controversial due to the risks of thrombus enlargement and embolization. In this case, we report an 8-year-old boy who was hospitalized for macrolide-resistant M. pneumoniae pneumonia. After experiencing abdominal pain, he was diagnosed with thrombosis in the pulmonary artery and mesenteric vein. Additionally, massive thrombi were found in the inferior vena cava and left common iliac vein, measuring approximately 4 cm and 4.5 cm in length, respectively. Following routine therapies of anti-infection and anticoagulation, the patient continued to experience recurrent abdominal pain, and there was a risk of the deep vein thrombi detachment. To avoid the shedding of thrombi, the patient underwent inferior vena cava filter placement and catheter-directed thrombolysis with alteplase on day 8 following admission. The clinical symptoms significantly improved, and thrombosis recurrence was not observed in the subsequent follow-ups. This case report highlights the need for prompt recognition of thrombosis in M. pneumoniae infection. Massive thrombus in deep vein is extremely rare but life-threatening in children. The optimal treatments remain to be determined due to the limited experience to date.