Sirolimus for the treatment of children with various complicated vascular anomalies

Vascular anomalies include a heterogeneous group of disorders that are categorized as vascular tumors or vascular malformations. Treatment options include resection, embolization, laser therapy, and sclerotherapy or medical treatment such as propranolol, steroids, interferon, and cytostatic chemotherapy. Mammalian target of rapamycin seems to play a key role in the signal pathway of angiogenesis and subsequently in the development of vascular anomalies. Recently, the successful use of sirolimus has been reported in children with lymphatic malformations and kaposiform hemangioendotheliomas. We report on six patients with different vascular anomalies (kaposiform hemangioendothelioma n = 2, combined lymphatico-venous malformation n = 2, pulmonary lymphangiectasia n = 1, and orbital lymphatic malformation n = 1) who were treated with peroral sirolimus. Three of the children initially presented with a Kasabach-Merrit phenomenon. Median duration of treatment was 10 months; two children are still on treatment. Three children each achieved complete and partial remission. Kasabach-Merrit phenomenon resolved within 1 month in all patients. Treatment with sirolimus was tolerated well; only mild reversible leukopenia was observed.

Conclusion: Sirolimus proved to be effective in children with complicated lymphatic or lymphatico-venous malformations and kaposiform hemangioendotheliomas. Treatment was tolerated well with acceptable side effects. The optimum length of treatment and possible long-term side effects have to be evaluated.