Background
VM are the most common type of vascular malformation, with an incidence
of 1-2 per 10,000 births (2). VMs are typically located in the skin or
mucosa, but can involve subcutaneous tissue, muscles, joints, nerves,
and internal organs (4,5,8). Most commonly, VMs present as soft
subcutaneous masses with bluish colored overlying skin. They can enlarge
with Valsalva maneuvers or on dependent positions (9). While VMs most
commonly appear in childhood, delayed presentation in adolescence or
adulthood can occur (3). Trauma, infection, hemorrhage, or hormonal
changes during puberty or pregnancy can lead to growth (4,10,11).
Spontaneous regression does not occur (4). VMs can be focal or diffuse
and may be associated with other malformation types in characterized
syndromes, such as Klippel-Trenaunay Syndrome (KTS) (3). The majority of
VMs are caused by gain-of-function mutations in the TIE-2 receptor
(12,13,14), which is integral to regulation of vascular proliferation,
migration and adhesion (14,15).