Sometimes they do not appear until adulthood. Defective blood flow has been associated with these lesions. As the lesion ages, the vessels enlarge and thicken to compensate for the increased blood supply. Low grade grow slowly with the child and high grade expand rapidly, growing faster than the child until the lesion may eventually become life threatening. An AV malformation is a firm mass.
Common sites are the lips and other head and neck areas.
Mixed malformations include a combination of two or more vascular lesions.