Kaposiform haemangioendothelioma: ultrasonographic features and risk factors for the Kasabach-Merritt phenomenon.

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor with high morbidity and mortality. The aim of this study was to evaluate ultrasonographic findings associated with KHE.The clinical and ultrasonographic findings of a cohort of 64 cases with pathologically proven KHE were retrospectively reviewed and analyzed between November 2014 and February 2021. Two subtypes were divided according to the presence or absence of the Kasabach-Merritt phenomenon (KMP). The KMP risk factors in patients with KHE were analyzed statistically.Among the 64 cases of KHE, 43 (67.2%) were accompanied by KMP. There was a positive correlation between the appearance of KMP and tumor size. KHEs had an increased risk of developing KMP if the lesions measured were >6 cm and if they belonged to the deep or mixed subtype. On ultrasonography, all KHE lesions were heterogeneous, and 81.3% were hypoechoic; 93.8% of KHEs exhibited ill-defined margins, 68.7% had strands branching into the adjacent tissue, and 84.4% presented marked hypervascularity. Elastography showed that central hypoechogenic lesion areas were hard, and surrounding hyperechogenic lesion areas were soft.KHEs can occur in different parts of childrens' bodies. On ultrasonography, the main findings are heterogeneous low erosions, indistinct margins, branching strangulation into adjacent tissues, and obvious hypervascularity. Patients with lesions larger than 6 cm or belonging to deep or mixed subtypes (musculoskeletal infiltrates) are at risk for developing KMP, and clinicians should be vigilant.