Heterozygous mutations in Factor V Leiden (FVL) or prothrombin G20210A (PT-G20210A) are relatively common; the presence of double-heterozygosity for these mutations is rare but may be as high as 5% in patients with deep vein thrombosis (DVT). Antiphospholipid syndrome (APS) is a rare autoimmune disorder and commonly presents in adolescents and young adults. This report describes the diagnosis, treatment, and outcome for acute presentation of extensive lower extremity DVT and saddle pulmonary embolism (PE) in a previously healthy 17-year-old male found to have multiple genetic risk factors including double-heterozygosity for FVL/PT-G20210A and concurrent APS, which is rare and not well-described.

Background: Children with cancer diagnosis are overall at a higher risk of thrombosis. For a newly diagnosed bland thrombus, patients are commonly started on anticoagulants to prevent further extension and embolization of the clot. In the rare instance that a pediatric patient has a tumor thrombus, the role of anticoagulation is less clear. Procedure/Methods: Patients under 21 years of age with a finding of tumor thrombus on imaging from 2010-2020 at Texas Children’s Hospital were identified and their medical records were reviewed. Results: A total of 50 patients were identified. Most thrombi were incidental findings at diagnosis; however, there were two patients who presented with pulmonary embolism (PE). Inferior Vena Cava extension was noted in 36% of the patients and 24% patients had an intracardiac tumor thrombus. Hepatoblastoma (26%) was the most common malignancy associated with tumor thrombus. Anticoagulation was initiated in 10 patients (20%). Only 2 of these 10 patients showed response to anticoagulation. However, 40% (4/10) patients in the anticoagulation cohort were noted to have bleeding complications (p <.05). Conclusion: Children with intravascular extension of solid tumors were not commonly started on anticoagulation at the time of diagnosis, irrespective of the extent of tumor thrombus. Furthermore, we observed a significant trend toward higher incidence of bleeding complications after initiation of anticoagulation. There is inadequate evidence at this time to support routine initiation of anticoagulation in pediatric patients with intravascular extension of solid tumors.

Objective: Effective treatment for acute limb-threatening lower extremity (LE) thrombosis involves thrombolysis in addition to anticoagulation. There is limited available data on the outcomes and safety of catheter directed thrombolysis (CDT) to help guide its use in pediatrics. Procedure: Single-center retrospective medical record review of children (<21 years of age) that received CDT for LE and inferior vena cava (IVC) thrombosis over a 5-year span at a pediatric tertiary care center. Results: A total of 29 patients were identified for inclusion in the study, 76% (n=22) received overnight CDT while 24% (n=7) received tissue plasminogen activator (tPA) as a bolus dose during a single interventional procedure. The median age of the cohort was 15.8 years (range 0-19.1). All patients were treated with a course of anticoagulation. The thromboses represented were extensive, with 93% (n=27) being occlusive and affecting multiple venous segments. Thrombus resolution occurred in 35% (n=10) of patients. Rivaroxaban use during the course of anticoagulation and estrogen-containing hormonal therapy use prior to diagnosis were associated with thrombus resolution, while Hispanic ethnicity was associated with thrombus persistence. There was one major and 3 minor bleeding events that occurred as a complication of thrombolysis and no treatment related deaths. Conclusions: The administration of tPA, whether by CDT or as an intra-procedural bolus, for extensive LE and IVC thromboses is effective and safe in children when combined with a course of anticoagulation.