Vascular anomalies may be categorized into two major groups:
- Hemangiomas (vascular tumors)
- Vascular malformations
Although lesions in these two groups may be similar in appearance, they are biologically and clinically distinct entities. The most important tool in making the proper diagnosis of a vascular anomaly is the natural course of the lesion and its appearance upon physical examination. Hemangiomas grow rapidly, and then begin to involute slowly, whereas vascular malformations grow with the child and generally do not involute. Frequently, radiographic studies, such as magnetic resonance imaging (MRI), angiography, and/or an ultrasound with Doppler flow may be necessary to confirm the diagnosis of vascular anomaly.
Vascular Malformations
Vascular malformations can be classified based on their vessel type (veins, arteries, capillaries or lymphatic vessels) and flow characteristics (slow vs. fast flow). For example, slow-flow malformations include capillary, lymphatic and venous malformations. Fast-flow malformations include arteriovenous malformations.
Capillary Malformations
Capillary malformations are slow-flow lesions that usually appear on the skin. The skin will appear deep purple or red and can be patchy and quite extensive. Flash-lamp pulse dye laser therapy is very effective in treating capillary malformations. Surgical excision may be indicated in some instances of skeletal and soft tissue overgrowth, although the indications are narrow.
Venous Malformations
Venous malformations are characterized by dilated, abnormal venous channels and can occur anywhere in the body. They appear as either a faint blue patch or a soft blue vascular mass. Most often, these lesions are located on the face, arms, legs or trunk. They may frequently be confused with deep hemangiomas and have often been incorrectly termed “cavernous hemangiomas.” As with most slow-flow vascular lesions, treatment of venous malformations usually requires application of compression garments as the initial line of treatment. Sclerotherapy combined with or without surgical debulking is the mainstay of the therapeutic approach for venous malformations.
Arteriovenous Malformations
Arteriovenous malformations (AVM) are fast-flow vascular lesions consisting of excess arteries connected directly to enlarged veins. The intervening tiny vascular architecture, or capillary network, is abnormal or absent. Arteriovenous fistulas, abnormal connections between arteries and veins, are frequently present. The result is a pulsatile mass. AVMs are present at birth, but often do not appear until infancy or later. As with other vascular malformations, surgical excision of an AVM, when possible, gives the best chance for a “cure.” However, this is often difficult and carries significant risk of bleeding.
Lymphatic Malformations
 Lymphatic malformation of the left buttock and lower leg. Lymphatic malformations are composed of malformed, dilated channels filled with lymphatic fluid (figure 2). Lymphatic malformations can be "microcystic" (small cysts), "macrocystic" (large cysts), or a combination of both. Treatments for each type will vary; therefore, proper diagnosis is essential. Most lymphatic malformations are present at birth or identified within the first two years of life. Sclerotherapy is the process of injecting a caustic material into the dilated channels in an effort to cause scarring and collapse of the vessel walls. This is performed by the interventional radiologist under general anesthesia and is well described for macrocystic lymphatic malformations. Often, the lesion will shrink in size, but will not completely disappear. Often, multiple sessions are required to effectively treat an area of lymphatic malformation. The only way to truly eradicate lymphatic malformations is to remove them surgically. Surgical excision is usually limited to symptomatic areas of the lesion and may even be dangerous in certain areas of the body where vital structures reside.
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