ABSTRACT Introduction: Although still rare, pulmonary embolism (PE) in children has been increasing over the years. Data regarding this group of patients are still sparse, which contributes to the lack of standardized prophylaxis protocols and the misdiagnosis. This study aimed to determine the incidence of pediatric PE at a Brazilian tertiary hospital, describe clinical characteristics and identify possible risk factors. We also analyzed the diagnosis and management of PE. Methods: This was a retrospective review of tertiary Brazilian single-center data of all pediatric patients (0 – 18 years) with acute PE, diagnosed radiologically, from September 2009 to May 2019. Results: The incidence of PE was 3.3 cases per 10,000 hospitalized children. All the twenty-three cases had some risk factor identified and sixteen of them (69.5%) had more than one risk factor. The most important were central venous catheter (39.1%), malignancy (34.8%) and recent surgery (34.8%). Among the children with identifiable symptoms (69.5%), the most common was dyspnea (56.2%). Only one patient did not receive antithrombotic therapy because of the high bleeding risk and most patients (70.6%) were treated for 3 to 6 months. Among the nineteen patients alive at the end of the six-month follow-up, ten (52.6%) repeated the PE image control. Seven of them (70.0%) had complete or partial resolution of the thrombosis and none had worsening images. Conclusion: Our lower incidence than that of the current literature may reflect underdiagnosis due to low suspicion of PE. At least one risk factor was identified in all patients, which emphasizes the importance of increasing awareness of high-risk children.

Abstract Introduction: Little attention is given to thrombosis associated with pediatric acute promyelocytic leukemia (APL). This study describes the thrombotic and hemorrhagic manifestations of APL in pediatric patients and evaluates their hemostasis, based on coagulation tests. Methods: Inclusion criteria were age 0–18 years and APL diagnosis between April 2005 and November 2017. Patients who had received blood transfusion prior to coagulation tests were excluded. Baseline coagulation tests, hematologic counts, and hemorrhagic/thrombotic manifestations were evaluated. Results: Median age was 10.7 years (1–15 years). The initial coagulation tests revealed a median Hgb of 8.3 g/dL (4.7–12.9 g/dL), median leucocyte count of 10.9 × 109/L (1.1–95.8 × 109/L), median platelet count of 31.8 × 109/L (2.0–109.0 × 109/L), median activated partial thromboplastin time (aPTT) of 31.7 s (23.0–50.4 s), median aPTT ratio of 1.0 (0.78–1.6), median thromboplastin time (PT) of 17.5 s (13.8–27.7 s), median PT activity of 62% (25–95 %), and median fibrinogen of 157.7 mg/dL (60.0–281.0 mg/dL). Three patients (13%) had thrombosis. At diagnosis, 21 patients (91.3%) had bruising, one patient (4.3%) had splenic vein and artery thrombosis and one patient (4.3%) presented without thrombohemorrhagic manifestations. During treatment, two patients (8.6%) had thrombosis. Conclusion: Knowledge of thrombosis in pediatric APL is important to determine its risk factors and the best way to treat and prevent this complication.