Thrombotic storm in a 4-year-old boy with a thrombus in the right atrium

Thrombotic storm (TS) is a rare disease, especially with thrombus in the heart of pediatric patient. We present a case of a 4-year-old boy, who was diagnosed with TS during his first hospitalization due to lower extremity deep venous thrombosis, pulmonary embolism, and thrombosis of the inferior vena cava, cerebral, left internal jugular, portal, renal, and iliac veins. He was eventually prescribed with rivaroxaban to control thrombosis after 30 days of successive use of low-molecular-weight heparin, unfractionated heparin, and warfarin, which were demonstrating little effect on preventing thrombosis, and the patient was intolerant to argatroban. While his lupus anticoagulant ratio was slightly above the normal range and no other potential causes such as congenital thrombophilia, severe infection, malignancy, and trauma were confirmed, we suspected antiphospholipid antibody syndrome and prescribed glucocorticoid and rituximab to control the disease. After 36 days of admission, ultrasonography showed recanalization of the former thrombus. One month after discharge, a tumor embolus resembling a mass emerged in his right atrium under effective anticoagulant therapy. During his second admission, he underwent surgical thrombectomy, and pathological examination confirmed the mass to be a platelet-rich thrombus rather than tumor embolus or infection. Considering the suspected antiphospholipid antibody syndrome as the cause of the TS, we prescribed aspirin combined with rivaroxaban to prevent thrombosis. In this case, surgery and pathology shed light on the type of thrombus that emerged from the inferior vena cava and traveled to the heart, which is the possible potential cause of TS. It also changed our therapeutic strategy to antiplatelet therapy combined with anticoagulant therapy to control the disease.