A venous malformation is an injury that is the result of dilated veins that form abnormally. These lesions are usually seen on the skin, but can also be present on the muscles, bones, or organs. They can occur in the brain, although according to Boston Children's Hospital, the estimated occurrence of this type of venous malformation is only about 0.5%.
Venous malformations are usually dark blue and smooth, although they can harden if a clot forms. They can range in size from pinhead-sized spots to large lesions many inches in diameter. A malformation may appear as a single lesion, or it may be one of many.
In a venous malformation, the vein walls lack the smooth muscle cells that characterize a normal vein. Although the exact cause is unknown, DNA studies in families with multiple venous malformations have shown mutations in genes responsible for communication between the cell lining and smooth muscle cells in the vein walls. There is no evidence to support the idea that any food or medicine during pregnancy can cause a venous malformation.
There are several diseases and conditions that involve venous malformations. Glomovenous malformations contain nerve cells and cause the malformations to stiffen and tighten. These types of malformations can be inherited and often occur in multiple locations. Blue gum bleb nevus syndrome involves numerous gum lesions that can appear both externally and internally.
Injuries to the stomach or gastrointestinal tract can cause severe abdominal pain and bleeding and usually need to be surgically removed to prevent these types of complications. Maffucci syndrome is characterized by venous malformations and bony growths called enchondromas. This can lead to severe deformities that can worsen with age, and lesions and enchondromas can become malignant, so ongoing x-rays and biopsies may be necessary.
Venous malformations are largely a cosmetic problem, but they can also cause other complications. They can expand and grow due to age, injury, puberty, or pregnancy, and can develop blood clots that can impede blood supply to areas surrounding the malformation. Many are also extremely painful and sensitive, making treatment necessary. A venous malformation in the stomach or brain can rupture and cause sudden bleeding, creating a medical emergency.
Very small venous malformations can be treated and removed with a laser, but most require other treatments. The two main treatment options are surgical removal and sclerotherapy. Sclerotherapy involves an injection into the venous malformation to shrink the abnormal vein and reduce the size and appearance of the malformation. These injections may need to be repeated several times, and surgical removal may still be necessary if the sclerotherapy treatment fails.