Sirolimus was first administered to an infant with kaposiform hemangioendothelioma (KHE) with Kasabach-Merritt phenomenon (KMP) refractory to other therapies (8), based on the high lymphatic component within this tumor, and that the PI3K/AKT/mTOR pathway is activated in angiogenesis and lymphangiogenesis. The gene discussed is PIK3CG; the disease is kaposiform hemangioendothelioma.