This trial is testing if taking sirolimus once a week can help people with venous and lymphatic malformations. These patients have few treatment options. Sirolimus aims to reduce abnormal growths by affecting the immune system. The study will also check for side effects and patient satisfaction over several months. Sirolimus has been used in various studies to treat lymphatic malformations and has shown potential in stabilizing lung function in patients with lymphangioleiomyomatosis.