Key Points• Upper limb PTS in children depends on DVT pathogenesis (primary vs secondary) and on the age of the patient (neonates vs non-neonates).• DVT pathogenesis and thrombus resolution are independent predictors of upper limb PTS in children.Despite its relatively estimated high occurrence, the characterization of pediatric upper extremity deep vein thrombosis (UE-DVT) and of UE postthrombotic syndrome (PTS) is still lacking. We investigated the occurrence, characteristics, and predictors of UE-PTS in a cohort of children with objectively confirmed UE-DVT. Patients were analyzed in 3 groups according to DVT pathogenesis and neonatal status: primary (G1), secondary neonates (G2 neonates ), and non-neonates (G2 non-neonates ). A total of 158 children (23 G1, 25 G2 neonates , and 110 G2 non-neonates ) were included. The most common triggering factors were effort-related (87%) in G1 and central lines in G2 neonates (100%) and in G2 non-neonates (92%). PTS scores ‡1, as per the Modified Villalta Scale, were identified in 87% of primary patients, 16% of G2 neonates , and 49% of G2 non-neonates . Survival analysis showed that the time to PTS score ‡1 significantly differed among group (log-rank test P < .0001).A multivariable logistic regression showed that DVT pathogenesis and imaging-determined degree of thrombus resolution at the end of therapy were independent predictors of a PTS score ‡2. In conclusion, pediatric UE-PTS frequency and severity depend on UE-DVT pathogenesis (primary/secondary) and, within the secondary group, on patient's age. Line-related UE-PTS has a more benign course, particularly in neonates. (Blood. 2014;124(7):1166-1173

Kaposiform hemangioendothelioma (KHE) is a rare infiltrative vascular tumor that may be associated with Kasabach-Merritt Phenomenon (KMP), which is a consumptive coagulopathy with potentially life-threatening thrombocytopenia. Management of KHE and KMP is challenging, and currently, there are no standardized validated treatment protocols. Mammalian target of rapamycin inhibitors have been shown to be effective in the treatment of KHE. We describe a term male who presented as a diagnostic dilemma with life-threatening pleural and pericardial effusions and severe thrombocytopenia. After extensive work-up the etiology for his condition was determined to be KHE with KMP. The patient was commenced on sirolimus and responded well to therapy with resolution of KMP.