Abstract: 【Abstract】 Objective To preliminarily assess the clinical value of sirolimus combined with prednisone in the treatment of Kaposiform hemangioendothelioma （KHE） complicated by Kasabach-Merritt phenomenon （KMP）. Methods A retrospective study was conducted. General clinical data and relevant data on efficacy and adverse reactions were collected from 36 patients with KHE complicated by KMP, who received oral sirolimus combined with prednisone in Department of Pediatric Surgery, West China Hospital, Sichuan University from January 2011 to January 2018. Results Among the 36 patients with KHE complicated by KMP, the male-to-female ratio was 1∶0.8; their average age was 15.0 months （range, 4.0 - 60.0 months）, and the average age of onset was 6.3 months （range, 0.8 - 48.0 months）; 32 （88.9%） patients were diagnosed with mixed KHE, and 4 （11.1%） with deep KHE; the tumor size ranged from 2.5 cm × 4.0 cm to 20.0 cm × 24.0 cm. During the combined treatment, the average duration of prednisone administration was 6.4 weeks （range, 5.0 - 9.0 weeks）, and that of sirolimus administration was 19.3 months （range, 13.0 - 27.0 months）. After 1 - 5 weeks of combined treatment, platelet counts and fibrinogen levels of the 36 patients gradually returned to normal. After short-term prednisone combined with long-term sirolimus treatment, the average disease severity score decreased from 4.0 before treatment to 2.4 at 6 months and 1.6 at 12 months. After 12 months of the combined treatment, tumors mostly regressed in 32 （88.9%） patients, partially regressed in 3 （8.3%）, showed no obvious change in 1 （2.8%）. During the treatment, common adverse reactions included gastrointestinal discomfort and oral ulcers, no patient discontinued the treatment due to severe adverse reactions, and no drug toxicity-related death occurred. Conclusion Sirolimus combined with prednisone is effective and safe for the treatment of KHE complicated by KMP.

Key words: Sirolimus, Prednisone, Hemangioendothelioma, Kasabach-Merritt phenomenon, Kaposiform hemangioendothelioma