Atypically presenting kaposiform hemangioendothelioma of the knee: ultrasound findings.

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor of early childhood and infancy. Kasabach-Merritt phenomenon, a common complication of KHE, is characterized by life-threatening thrombocytopenia, hemolytic anemia, and consumption coagulopathy. There may be atypical cases that do not present with Kasabach-Merritt phenomenon and do have atypical imaging findings. Knowledge of atypical imaging features may assist radiologists in identifying KHE. In this report, we present a 4-year-old case of KHE with atypical ultrasound findings.