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A venous malformation is a lesion that is a result of dilated veins that are abnormally formed. These lesions are typically seen on the skin, but they can also be present in muscle, bone, or organs. They can occur on the brain, though according to the 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 soft, though they can become hardened if a clot forms. They can range in size from pinhead-sized dots 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 walls of the vein 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 the genes responsible for the communication between cell lining and the smooth muscle cells in the walls of the vein. There is no evidence supporting the idea that any food or medication 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 become hardened and tense. These types of malformations can be inherited and often occur in multiple places. Blue rubber bleb nevus syndrome involves numerous rubbery lesions that can appear both externally and internally.
Lesions in the stomach or gastrointestinal tract can cause severe abdominal pain and bleeding and must usually be surgically removed to prevent these types of complications. Maffucci's syndrome is characterized by venous malformations and bony growths called enchondromas. These can result in serious deformities that may worsen with age, and the 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 cause other complications as well. They can expand and grow due to age, injury, puberty, or pregnancy, and can develop blood clots that may impede the supply of blood 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 may 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 sclerotherapy treatment fails.