Vascular Malformation is a general term that includes congenital (since birth) vascular anomalies of arteries, veins or lymph vessels. These all are present at birth, and become apparent at different ages.
Depends on the location in the body, but most commonly pain, swelling, bleeding, birthmarks, etc.
Now the best available treatment for vascular malformation is embolisation, although open surgery is sometimes useful. Embolisation can be performed using medical glue, onyx, sclerosant like STS, bleomycin, absolute alcohol.