Sirolimus for the treatment of vascular tumors and malformations in children: A 10-year single-institution retrospective study.

BACKGROUND

Vascular anomalies, including vascular tumors and vascular malformations, are common pediatric conditions that may cause significant morbidity. Although standard treatments are effective in many cases, a subset of patients experiences inadequate responses or has unresectable disease, necessitating alternative therapeutic strategies. Sirolimus has emerged as a targeted treatment option for selected vascular anomalies.

AIM: To evaluate treatment outcomes and the safety of sirolimus in children with vascular anomalies.

METHODS

We conducted a retrospective review of medical records of pediatric patients with vascular anomalies who received sirolimus at Chiang Mai University Hospital between 2016 and 2025. Clinical characteristics, treatment regimens, therapeutic responses, and adverse events were analyzed.

RESULTS

Eleven children were included in the study. Five patients had vascular tumors, including two kaposiform hemangioendotheliomas, one composite hemangioendothelioma, and two hemangiomas, while six patients had vascular malformations. Sirolimus was administered as salvage therapy in nine patients. After sirolimus treatment, 10 patients (90.9%) achieved partial response, and one patient had stable disease. At a median follow-up of 30 months, all patients were alive with disease. Sirolimus-related adverse events occurred in four patients, with proteinuria being the most common. Other events included hypokalemia, elevated serum creatinine, and hypercholesterolemia. No serious infections were observed.

CONCLUSION

Sirolimus demonstrated a high response rate and an acceptable safety profile in children with vascular anomalies. These findings support the use of sirolimus as an effective treatment option for refractory or unresectable cases, including complex entities such as composite hemangioendothelioma.