Role of Sirolimus in Advanced Kaposiform Hemangioendothelioma.

Kaposiform hemangioendothelioma (KHE) is an infiltrative vascular tumor that classically presents in infancy. Management typically focuses on treating Kasabach-Merritt phenomenon (KMP), a disorder of severe and at times life-threatening platelet trapping. However, the morbidity of KHE extends beyond KMP. The infiltrative nature of the tumor can lead to long-term disability and often makes complete surgical resection impossible. We report the case of a 10-year-old boy with a KHE of his right distal thigh who was unable to walk without assistance due to fibrotic change and right knee contracture. He had no laboratory evidence of KMP at the time of representation. Rapamycin was started in hopes of reducing the tumor burden. Within 2 months of therapy, fibrotic areas softened, his contracture nearly resolved, and there was marked improvement in his mobility. Rapamycin has been previously reported to be effective in managing cases of KHE complicated by KMP. Our report emphasizes the role for rapamycin in the treatment of KHE in the absence of KMP through the inhibition of vasculogenesis and fibrotic pathways.