Venous malformations (VMs) are ectatic vessels that are morphologically and histologically similar to veins and have a low blood flow. The thin-walled vascular channels are composed of a deficient layer of smooth-muscle cells and are lined by quiescent endothelium. The TIE2 signaling pathway is critical for endothelial cell–smooth muscle cell communication in venous morphogenesis.1 Venous malformations represent approximately one-half to two-thirds of all vascular malformations, and the majority of them are sporadic anomalies. The skin or mucosa that covers VMs varies in color according to the depth and degree of ectasia of the lesion. More superficial malformations are purple and deeper ones are blue, green, or even imperceptible. The lesions are soft to the touch, can have a nodular appearance, and empty with compression. Highly ectatic vessels sometimes contain small venous thromboses, producing pain and inflammation. Phleboliths, which are used as radiological markers of this type of malformation, can be present from an early age.
Redondo P. The Hidden Face of Venous MalformationsA Multidisciplinary Therapeutic Approach. Arch Dermatol. 2008;144(7):922-926. doi:10.1001/archderm.144.7.922