Abstract: Objective To explore the efficacy of sirolimus in treatment of microcystic lymphatic malformation in children.Methods Nine children with microcystic lymphatic malformation were selected and treated with sirolimus orally.The sirolimus was taken orally with the dose of 0.05~0.10 mg/Kg·d in 1-2 times.The treatment lasted for 3-6 months and further consultation was required once a month during the treatment.Tumor size and complications were observed.Results All patients were followed up for 6-18 months.In 7 cases who received early treatment,the curative effect was good with obvious atrophy of the tumor,and in 2 cases who started treatment when they were over 10 years old,the curative effect was poor with no obvious shrinking of the tumor.No obvious abnormalities were found in blood routine,blood glucose,blood pressure,heart function,liver and kidney function.Only 1 patient had immune decline,but it was tolerable.Conclusion Sirolimus is effective and safe for the treatment of microcystic lymphatic malformation in children and early treatment is necessary.

Key words: Sirolimus, Children, Microcystic lymphatic malformation