Vascular malformations include a variety of complex lesions, with infantile hemangiomas being the most common and other types of lesions being less common and understudied. Although some lesions are benign, they can invade vital structures and cause malformations or be life-threatening. Vascular tumors such as Kaposi-like hemangioendothelioma (KHE) and complex vascular malformations are quite difficult to treat. Hammill et al. treated six patients with complex, life-threatening vascular malformations with the mTOR blocker rapamycin (rapamycin, sirolimus), and all six patients received multiple other treatments that failed. After rapamycin treatment, all showed significant improvement in clinical manifestations and tolerable side effects. Rapamycin is considered safe and effective as an important treatment for life-threatening vascular malformations, and a phase II safety and efficacy trial is currently underway. Rapamycin (RAPA), also known as sirolimus, is a novel macrolide immunosuppressant. Rapamycin exerts immunosuppressive effects by blocking signaling through different cytokine receptors, blocking the progression of T lymphocytes and other cells from the G1 to S phase. Included diseases: Kaposiform Hemangioendotheliomas, Tufted Angioma, Capillary Venous Lymphatic Malformation, Venous Lymphatic Malformation, Microcystic Lymphatic Malformation, Mucocutaneous Lymphangiomatosis and Thrombocytopenia, Capillary Lymphatic Arterial Venous Malformations, PTEN Overgrowth Syndrome With Vascular Anomaly, Lymphangiectasia Syndromes. The initial dose was 0.8 mg/m^2 twice daily at 12 h intervals. The dose was subsequently adjusted to maintain a low blood pressure letdown level of 10-15 ng/mL with concomitant administration of cotrimoxazole tablets ( 15-25 mg/kg, bid, 3 days/week) or pentamidine (antiprotozoal infection drug)) to prevent pneumonia. The mean time to onset of action was 25 d (8 to 65 d), 4/6 patients had discontinued the drug, and 2 had been on it for more than 1 year without recurrence of symptoms. We treated several cases of complex vascular malformations with rapamycin, including one case of megalingualism due to lymphatic malformation and one case of KTS with good results, and the results of several other cases are under observation and evaluation. No adverse effects requiring management were observed during treatment. The major toxic side effects of rapamycin include headache, nausea, dizziness, rhinorrhea, and joint pain. Abnormal laboratory tests include thrombocytopenia, leukopenia, decreased hematocrit, hypertriglyceridemia, hypercholesterolemia, hyperglycemia, elevated liver enzymes (SGOT, SGPT), elevated lactate dehydrogenase, and hypokalemia and hypomagnesemia. Eyelid puffiness has also been reported with rapamycin administration, and the cause of lower plasma phosphate levels is thought to be prolonged excretion of phosphate from the kidneys with rapamycin-based immunosuppressive therapy. As with other immunosuppressive agents, RAPA has an increased chance of infection, with a reported tendency for increased pneumonia in particular, but the occurrence of other opportunistic infections is not significantly different from cyclosporine. 【Commercial name】Rapamycin 【Generic name】Sirolimus Tablets, Alias: Rapamycin 【English name】Sirolimus Tablets 【Specifications】1mg*10 tablets/box