Definition
A venous malformation (VM) is a collection of abnormally formed veins. Unlike normal veins that have well developed muscle in the wall, a venous malformation has a very poorly formed wall with less muscle than normal. The weakness of the wall of the veins is believed to cause them to gradually stretch or enlarge over time. A VM can develop in any part of the body.

Symptoms And Signs
Venous malformations typically cause swelling and enlargement of the affected area, often associated with pain. Swelling occurs when the VM fills with blood, and the blood remains in the abnormal veins. The swelling worsens when the effected area is lower than the rest of the body (dependency) or when the pressure in the veins rises (for example, during a Valsalva maneuver or breath-holding). VMs are soft. Usually, they can be indented when you press on them and get smaller when the effected area is raised. When the skin is involved with the venous malformation, it typically looks blue or purple. Because the blood in a VM circulates very slowly, blood clots form and may calcify, causing "phleboliths" or vein stones. The formation of blood clots is often painful, and can cause the malformation to become swollen and firm. Symptoms vary according to the location of the VM. Those involving the tongue or other structures around the airway may cause problems with breathing or speaking, while those in the arms and legs typically cause painful swelling. Rarely, blood clots that form in a VM can travel to the lungs, causing a pulmonary embolus. An extremely large VM can consume blood clotting proteins, causing localized intravascular coagulation, where the body loses some of its ability to form blood clots.

Diagnosis
A VM that involves the skin and superficial tissue can often be diagnosed by physical examination, if the physician is familiar with vascular anomalies. Magnetic resonance imaging (MRI) is the best imaging test to diagnose a VM, and to determine the extent. Ultrasonography is also useful to make the diagnosis when the VM is near the surface. Angiography is usually not needed to make the diagnosis.

Treatment Of Venous Malformations
A VM that is not causing symptoms does not need to be treated. Basic treatment consists of the use of graded elastic compression stockings or sleeves (for a VM of the leg or arm) to prevent swelling and low-dose aspirin to minimize the formation of painful blood clots. When these measures are not adequate, techniques are used to close or remove the enlarged venous spaces:

• Sclerotherapy is a technique that is performed in an angiography suite (an operating room containing specialized X-ray and Ultrasound equipment), usually under general anesthesia. A needle is placed into the VM, contrast medium is injected to outline the VM on x-ray, and then a sclerosant is injected into the abnormal veins. This damages the veins and causes gradual shrinkage. It usually needs to be performed repeatedly to cause complete and permanent shrinkage.
• Endovenous laser therapy is similar to sclerotherapy, but involves placing a diode laser fiber through a needle or catheter to damage the veins. It is useful for treating large venous channels or spaces and is often combined with sclerotherapy. The combination of endovenous laser therapy and sclerosant injection appears to result in a more rapid response and an easier recovery from the procedures.
• Venous embolization is a technique where permanent devices such as coils or embolization glue (NBCA) is injected or placed through a catheter to seal off the VM where it connects to the circulating veins. It is often combined with sclerotherapy or surgery.
• Surgical excision involves removing the abnormal veins and the tissue around them. This is most often used in facial VM, to restore a more normal facial contour. Usually, surgery is performed after sclerotherapy, which helps to reduce bleeding and makes the VM easier to remove.

Prognosis
Venous malformations are believed to be the result of a genetic abnormality in the affected tissue. Therefore, except for small lesions, VM are not curable. Regardless of the treatment used, they will probably re-occur. In spite of this fact, it has been shown that treatment is helpful in the long term to control the growth and the symptoms. Extensive VMs often require a series of ablation procedures, and then additional treatment a few years later. Most patients live relatively normal lives, and many are high achievers in school, physical activities and careers.