VMs are present at birth. They are clinically not always apparent and tend to grow in proportion to the growth of the child. The growth is most pronounced during puberty and pregnancy. These are congenital lesions that affect boys and girls of equal frequency with a reported incidence of 1–2 per 100,000 births and a prevalence of 1 % [7].

Most VMs (95 %) are sporadic, but can be seen in a number of heritable conditions. The molecular basis for sporadic is yet to be discovered, however there are familial cases where the genetic defect has been localized on a specific chromosome. In 1994–1995, two families were identified to have autosomal dominant inherited cutaneous and mucosal VMs. Genetic analysis mapped a locus for both of these families to the chromosome 9p21 [8, 9]. These families shared a mutation resulting in an arginine to tryptophan substitution R849W in the gene that encodes the kinase domain of the endothelial cell receptor Tie2 [10]. In 1999, four more families with autosomal dominant inherited VMs were identified [11]. Only one of those families shared the same mutation as the previous two reports. The second family had a novel hyperphosphorylating Y897S mutation in the TIE2 gene. The other families showed no evidence of linkage to 9p21, which suggests genetic heterogeneity. Multifocal VMs are most commonly seen in the familial forms of VM, including the following: Blue rubber bleb nevus (BRBN) syndrome, Mucocutaneous familial VMs, Glomovenous malformation, and Maffucci’s syndrome [12].

Ultrasound: On gray-scale imaging, VMs usually are hypoechoic to anechoic with the shape of tubular structures [13]. Some lesions can have a heterogeneous echotexture if phleboliths or different forms of thrombus are present within the lesion. Doppler ultrasound is usually a monophasic low-velocity waveform. Sometimes flow can only be seen with compression and release of the lesion [14].

Computed tomography: On non-contrast CT, VMs are usually hypoattentuating, however, they can be heterogeneous depending on the amount of fatty tissue within the lesion. Phleboliths or dystrophic calcifications can be seen within the lesion. After the administration of contrast, the lesion usually enhances at the periphery and then fills in centrally on the delay images [14]. CT is excellent at looking for boney involvement from the lesion. MRI is better at characterizing the lesions relationship to the surrounding soft tissue structures .

MRI: VMs appear usually as hypointense to isointense on T1-weighted imaging. They can however have areas of bright signal on T1-weighted images if the lesion has fat, subacute blood products, or certain types of calcifications contained within the lesion [15]. On T2-weighted images, VMs have high signal intensity. Gradient echo sequence usually shows areas of low signal corresponding to calcification, hemosiderin, or thrombus. The best sequence to determine the fully extent of the lesion and its relationship to surrounding soft tissue structures is the T2-weighted sequence [16]. On T1-weighted post contrast imaging, the lesions usually demonstrates early peripheral enhancement that later fills in centrally on delayed imaging [17].

Diagnostic venography: Contrast venography is helpful in the anatomical characterization of a VM. It is performed to determine the fully extent of the malformation and its draining veins. It is also helpful in confirming patency of the deep venous system in the extremity. Venography is also performed to determine the volume of contrast needed to fill the malformation before empties into normal draining veins .

Based on the pattern of venous drainage Dubois and Puig divided VMs into four types [18–20]. This drainage pattern is a reflection of the response to the treatment and rates of complications. Types I and II respond best to sclerotherapy with a better control rate and a lesser number of sessions to achieve control. Types III and IV have a higher rate of complications [20] .

VMs can be treated percutaneously by injecting a sclerosing agent. The most commonly described sclerosing agents (Table 22.2) included: alcohol, sodium tetradecol, ethibloc, polidocanol, and bleomycin [19, 21–24]. The procedure is performed under general anesthesia, since injection of the sclerosing agent can be extremely painful. A foley catheter is placed in the bladder to monitor urine output and color, since some patients may develop a hemoglobinuria. This is most likely to happen in younger patients and in patients with large lesions. In addition, if an extremity is being treated, we start an IV distal to the lesion to infusion saline and heparin overnight to flush out the sclerosing agent and prevent acute deep venous thrombosis [12]. Sclerotherapy is performed by cannulating the lesion percutaneously under ultrasound or fluoroscopy. Contrast material is injected to define the extent of the lesion, determine the flow rate within the lesion and the communication with normal veins, the presence of a possible arterial component, and to give an estimate of the volume of sclerosing agent needed to fill the lesion. If a large draining vein is visualized, these can be treated with embolization utilizing coils, liquid embolic agents, or with temporary balloon occlusion to increase the contact time of the sclerosing agent with the VM and to prevent egress of the agent into the systemic circulation [12]. This may also be performed with a tourniquet, blood pressure cuff, or manual compression. The VM is accessed with ultrasound guidance and the sclerosant is then injected under fluoroscopic guidance to decrease the risk of extravasation, overfilling of the lesion, and limit undesired egress of the sclerosing agent into the normal deep veins (Fig. 22.1). Overfilling of the lesion may also be prevented by the two-needle access technique, which allows decompression of the lesion through the second needle access. Cone beam CT can be performed to evaluate the anatomical distribution of the administered sclerosant and compare the distribution to the preprocedure imaging [25]. After the needles are removed, a 20–30 mmHg compression stocking is placed over the area of concern so that the veins do not refill with blood. This allows maximum contact of the damage circumference endothelium of the vein walls, promoting fibrosis and scarring. The procedure is then repeated at 8–10 weeks intervals, until there is no recanalization, swelling, or pain from the lesion. Diffuse VMs are much more difficult to treat. The area of maximum symptomatology is usually targeted, since these lesions cannot be completely obliterated .

After sclerotherapy, the lesion should feel firm to palpation. Swelling is generally maximum 24 h after the procedure. We recommend placing a custom fitted class II compression garment over the lesion as soon as possible. If the lesion involves the airway, the patient may need to be kept intubated overnight in the ICU. The patient is given IV steroids in the hospital and then sent home on a tapered dose pack. The affected area is kept elevated above the heart with ice packs applied to minimize swelling. Patients receive IV fluids twice the maintenance dose before, during, and after the sclerotherapy for 24 h. Urine output is closely monitored for hemoglobinuria. Appropriate IV and oral analgesics and anti-inflammatory agents are prescribed in the hospital and post discharge for 7 days afterwards.

Patients with extensive limb lesions should be instructed from childhood in the proper use of compression garments. Compression helps to decrease the discomfort associated with the lesion, protects the overlying skin, limits swelling, and improves localized intravascular coagulation.

In patients with extensive VMs in whom a low fibrinogen is present, the use of low molecular weight heparin is recommended for 2 weeks pretreatment and possible cryoprecipitate transfusion if still low on the day of the procedure. This therapy will reduce the consumptive coagulopathy of the extensive VM and potentially lower the recanalization rate [12] .