Inclusion Criteria:
* Patients with complex vascular anomalies that are refractory to standard care such as medical treatment, surgical resection and/or sclerotherapy/embolization (ineffective or accompanied by major complications)
* Patients must have adequate medullary function: Hemoglobine\> 10,0 g/dl, neutrophils \>1500/mm³ and platelets \> 100.000/mm³
* Patients must have the following laboratory values:
* Total serum bilirubin ≤ 1.5 x ULN (or totally bilirubin ≤ 3 x ULN with direct bilirubin ≤ 1.5 x ULN in patients with well documented Gilbert Syndrome)
* Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 x ULN (or \< 5.0 x ULN if hepatic metastases are present)
* Serum creatinine 1.5 x ULN. If the serum creatinine is ≥ 1.5 x ULN, then a 24-hour Creatinine Clearance must be conducted and the result must be ≥ 60 mL/min.
* Karnofsky \> 50
* Patients have to be able to sign the informed consent
* Women in age of procreation have to be informed that contraceptive methods are mandatory during the study time
Exclusion Criteria:
* Any of the following concurrent severe and/or uncontrolled medical conditions, which could compromise participation in the study or interfere with the study results:
* Impaired cardiac function or clinically significant cardiac diseases, including unstable angina pectoris, ventricular arrhythmia, valvular disease with documented compromise in cardiac function, myocardial infarction within the last 6 months, documented by persistent elevated cardiac enzymes or persistent regional wall abnormalities on assessment of LVEF function, history of documented congestive heart failure (New York Heart Association functional classification III-IV), documented cardiomyopathy, family history of congenital long or short QT, or known history of QT/QTc prolongation of Torsades de Pointes (TdP)
* Impairment of Gastro-Intestinal (GI) function or GI disease that may significantly alter the absorption of sirolimus (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea ≥ Grade 2, malabsorption syndrome, or small bowel resection)
* Known hypersensitivity to drugs or metabolites from similar classes as study treatment.
* Patient has other concurrent severe and /or uncontrolled medical condition that would,in the investigator's judgment, contraindicated participation in the clinical study (e.g. acute or chronic pancreatitis, liver cirrhosis, active chronic hepatitis, severely impaired lung function with a spirometry ≤ 50% of the normal predicted value and/or O2 saturation ≤ 88% at rest, etc.)
* Immunocompromised patients, including known seropositivity for HIV
* Pregnant or lactating women
* Prior treatment with PI3K and/or mTOR inhibitors
