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VASCULAR MALFORMATIONS
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AT-A-GLANCE
The worldwide prevalence is roughly 0.3%, mostly accounted for by capillary malformations.
Congenital, localized (although sometimes extensive or multifocal), and well-demarcated lesions of malformed vessels of various types: capillary, venous, lymphatic, arteriovenous, and combined
Histologically consist of enlarged, tortuous vessels of various types.
Caused by inherited or somatic mutations in various gene
Can be isolated, combined, or part of a syndrome
Management: multidisciplinary approach
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Vascular malformations are believed to arise because of errors in the development of vessels that occur during the 4th to 10th weeks of intrauterine life. Most vascular malformations are sporadic, although several families with inherited forms have been identified. They are very heterogeneous.1
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For many years, vascular anomalies were grouped under the term angioma, hampering precise classification and leading to incorrect diagnosis and improper management. For example, the term hemangioma has been used both for vascular malformations, often venous (cavernous hemangioma), as well as for vascular tumors (strawberry hemangioma). This nomenclature changed in 1982 with the development of a biologic classification by Mulliken and Glowacki.2,3 This classification system organized vascular anomalies based on clinical, hemodynamic, radiologic, and histologic features. It divided vascular anomalies into two major categories: (1) vascular tumors (with cellular proliferation, hemangioma being the most common; see Chap. 118), and (2) vascular malformations (structural anomalies of blood vessels) that are subsequently subdivided, depending on the affected vessel type, into arterial, capillary, lymphatic, or venous malformations (VMs). In 1996, this classification was adopted and further developed by the International Society for the Study of Vascular Anomalies (ISSVA; Table 147-1).4
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Vascular malformations mostly affect a single vessel type (Fig. 147-1), yet combined malformations also exist. They are named according to the affected vessel types, capillary-venous or venolymphatic malformation, for instance. In addition to isolated forms, vascular malformations occur in syndromes such as Klippel-Trenaunay syndrome (KTS, capillary-lymphatic-VM with limb hypertrophy), Maffucci syndrome (multiple enchondromas ...