This pilot trial studies sirolimus versus sirolimus plus pednisolone in treating patients diagnosed with kaposiform hemangioendothelioma (KHE) and Kasabach-Merritt phenomemon (KMP) that cannot be removed by surgery. The purpose of this study is to compare the efficacy and safety of orally administered sirolimus versus sirolimus plus pednisolone in the treatment of KHE associated with KMP.