The role of sirolimus in the treatment of vascular anomalies

Vascular anomalies are classified by the International Society for the Study of Vascular Anomalies (ISSVA). They result from an abnormal embryonic development of vessels, and in most cases, they are present at birth. A minority of VAs manifest at a later stage. They grow along with the child and may enlarge spontaneously during an infection. They often create aesthetic flaws, pain, impaired quality of life and require challenging treatment options that frequently do not provide patients with desired results. Part of these anomalies are classified as lymphatic. Proper diagnosis is based on radiological tests, including ultrasonography, computed tomography and magnetic resonance. It is vital to establish a correct diagnosis that precedes the appropriate treatment. The mammalian target of rapamycin (mTOR) inhibitor sirolimus is an effective treatment for difficult lymphatic anomalies. This article presents the current use of sirolimus and its antiproliferative properties that enables mTOR pathway inhibition, leading directly to stopping, reversing or minimising the effects of development of vascular anomalies. So far, it has been proven that sirolimus has a measurable effect on lymphatic malformations, is well tolerated, manageable and rarely produces adverse effects. Still, there are no guidelines for sirolimus care in patients with vascular anomalies as we lack prospective clinical trials.