Vascular malformation https://en.wikipedia.org/wiki/Vascular_malformation
Vascular malformation is an abnormality of blood vessels or lymphatic vessels. The lesion may cause aesthetic problems as it grows and can continue to enlarge throughout life.

More information ― English
References Congenital arteriovenous malformation (ISSVA classification for vascular anomalies) - Case reports 38435403 
NIH
Presenting a Magnetic Resonance Imaging (MRI) finding of a 7 year, 5-month-old male who was brought to our rural hospital by his father with chief complaints of swelling over his right hand since birth. His father narrated that the swelling is increasing significantly and the child has tenderness over swelling. The child underwent an angioembolism 1 month ago and has been brought for re-embolism. Now sclerotherapy has been planned for the patient.