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VM is a bluish lesion on the skin, mucous membrane, or in any organ system. It is composed of abnormally formed, dilated veins. The walls of these channels are unusually thin because of a relative lack of smooth muscle cells. VMs are the most common type of symptomatic vascular malformation. The older, incorrectly used term for VM is cavernous hemangioma.
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The deficiency of smooth muscle lining cells may be critical. DNA studies from rare families with multiple VMs have shown mutations (alterations) in genes responsible for the formation of and communication between the endothelial lining cells and the smooth muscle cells in the walls. No known food, medication, or activity during pregnancy can cause a VM.
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VMs are usually present at birth, but are not always seen. They can appear in childhood, adolescence, or adulthood.
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They are most common in the skin, but can be present in other tissues, e.g. muscle or bone, or in any organ, e.g. the bowel, liver, or spleen. The estimated incidence of VMs of the brain in the general population is 0.5%.
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They are dark blue and are usually soft, although they can become firm if a clot forms in the VM. The appearance of VMs ranges from small dots to large lesions involving skin and muscle. They can be single or multiple.
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A specialist should be contacted whenever a VM becomes symptomatic (is in a critical location, such as around the eye, on the face, or in the neck, or if it involves the hands, feet, or an internal organ, such as the gastrointestinal tract, liver, or brain).
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VMs tend to grow proportionately--in other words, they grow at the same rate as the child. They also can suddenly expand as the result of clot formation within the VM. They also can enlarge as the result of injury or during puberty and pregnancy, or if a woman is taking birth-control pills. Large VMs can be associated with a clotting abnormality. A VM within the brain or gastrointestinal tract can suddenly bleed.
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The history and physical findings usually provide sufficient clues as to the diagnosis. The bluish appearance is typical. VMs also tend to be painful, particularly in the morning upon arising, or if they are struck. VMs often swell if the affected region is made dependent (lowered below the level of the heart). VMs in the head/neck region enlarge when the patient tries to force air from the lungs with the vocal cords held closed (Valsalva maneuver). The diagnosis can be made or confirmed by ultrasonography, magnetic resonance imaging (MRI), or computed tomography (CT). VMs of the gastrointestinal tract are often best seen by looking in the mouth or the rectum with a telescope-like device called an endoscope (endoscopy).
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Only very small VMs can be treated with a laser. The two main treatment strategies are sclerotherapy (injection of an irritating solution to shrink the abnormal veins) and surgical removal (either total or subtotal). Sclerotherapy for all but small lesions should be done by an experienced interventional radiologist.
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Mutations in several genes that cause VMs have been discovered by DNA analysis of families that have multiple lesions. These discoveries will enable investigators to better understand how VMs occur and may lead to the development of new treatments.
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Glomovenous malformation (GVM) is the most familiar form of VM. The cutaneous (skin) lesions contain glomus cells in the walls of the abnormal channels. Glomus cells are abnormally-formed smooth muscle cells believed to function in the normal regulation of blood flow. From studying families with these lesions, the gene is located on chromosome 1p, it is called glomulin. The lesions are often multiple and can occur in any part of the body as blue-purple, often painful, nodules or large plaques.
Cerebral-cavernous malfomration (CCM) is a familial disorder characterized by the formation of multiple VMs in the brain. These lesions often bleed and expand. About 10% of patients with this disorder develop skin VMs. The causative gene is KRITI.
Blue rubber bleb nevus syndrome is characterized by of multiple VMs of the skin and internal organs. The rubbery, bluish lesions vary in size from a pinhead to many centimeters in diameter. They can occur on the trunk and limbs, as well as within the gastrointestinal tract, where they may cause bleeding and anemia. The lesions tend to get larger and more numerous over time and may be painful. The intestinal lesions can cause lifelong bleeding, intermittent abdominal pain, or sudden bowel blockage. They are difficult to confirm by computed tomography (CT) or magnetic resonance imaging (MRI), and may require endoscopy and nuclear medicine imaging for diagnosis. The intestinal lesions, of which there may be hundreds, can be successfully treated by an interdisciplinary endoscopic and surgical approach in which as many lesions as possible are removed.
Maffucci syndrome is a condition involving multiple enchondromas (benign bony growths) and VM-like lesions of the skin. The enchondromas develop in childhood and cause deformities due to abnormal bone development. They can degenerate to malignant (cancerous) bone tumors. Diagnosis is made by clinical examination and conventional radiographs.
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