Fig. 6

Kaposiform Hemangioendothelioma in a 13-month-old boy with moderate Kasabach-Merrit phenomenon (platelet count at 70,000/μl at admission). The boy presented with a large mass at the right upper arm, extending toward the elbow circumference of the distal humerus. The mass included severe purpura and ecchymoses, was tensely swollen with accompanying lymphedema (a). Arterial feeders to the lesion could be identified on MRA (b). A massive tumor blush was observed during the later arterial contrast phase (c). Fluid-sensitive sequences (d, e) revealed extended edema with characteristic septa perpendicular to the skin surface that showed contrast enhancement on delayed-phase T1w (f). Dilated veins were present around the primary tumor (g). Following an interdisciplinary consensus, it was decided to proceed with embolization, accompanied by treatment acetylsalicylate acid and sirolimus. Angiogram confirmed hypertrophic arterial feeders directed toward the lesion, but absent arterio-venous shunting (h). Onyx embolization was performed to exclude ~ 75% of the arterial tumor vasculature (i, j). Kasabach-Merrit phenomenon resolved with thrombocyte levels returned to normal 3 weeks after embolization. Three months after embolization and start of ASS and sirolimus treatment, the lesion had markedly regressed in size, the lymphedema had disappeared, and discoloration was regressing (k), 6 months later a mild discoloration persisted, without residual mass (l). Similarly, there was no relapse of the Kasabach-Merrit phenomenon