Background: While rare in children, chylothorax is a significant cause of respiratory morbidity and can lead to malnutrition and immunodeficiency. Historically, the traditional pharmacological treatment has been octreotide. There are several treatments that have been utilized in the past few years including sirolimus, however data regarding their efficacy and outcomes is limited. Furthermore, sirolimus has proven efficacy in complex vascular malformations, and hence, its utility/efficacy in pediatric chylous effusions warrants further investigation. Methods: In this retrospective study at Texas Children’s Hospital, data were extracted for all patients with chylothorax who were treated with sirolimus between 2009 and 2020. Details regarding underlying diagnosis, co-morbidities and number of days from sirolimus initiation to resolution of effusion were collected. Descriptive statistics were used to analyze the study cohort. Results: Initially a total of twelve infants were identified. Among them, seven patients had complete data and were included in the study. The mean duration of sirolimus treatment needed for chest tube removal was 16 days, with a median of 19 days and range of 7- 22 days. Chest tube output corresponded with sirolimus serum trough levels and trended down prior to chest tube removal. Conclusion: With close monitoring, sirolimus is a safe and effective therapy for pediatric lymphatic effusions even in critically-ill infants. The study also demonstrates shorter duration of chest tube requirement after initiation of sirolimus compared to previous studies. Our conclusion is based on a small case series due to the rare incidence of the condition.

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.