High-flow vascular malformations: literature review and case report.

F acial vascular malformations can cause dental emergencies that result in fatal or life-threatening and disfiguring situations. 14 Dentists must be aware of the clinical manifestations of these lesions in order to prevent iatrogenically related accidents and to minimize potential spontaneous crises for the patient. Effective treatment depends on the type and location of vascular lesion. Literature review is difficult because of the variation in terminology of vascular lesions. Terms such as arteriovenous aneurysm, cavernous hemangioma, central hemangioma, pulsating hemangioma, angioma, cirsoid aneurysm, arteriovenous shunt, arteriovenous fistula, and arteriovenous malformations have been used synonymously with vascular malformation.7,8 Prior to the 1980s, vascular lesions frequently were lumped under the term hemangiomas, which were considered hamartomas -congenital lesions comprised of normal tissues of faulty composition. 9 However, Glowacki and Mulliken1° suggested that vascular lesions be divided into two major groups -hemangiomas and vascular malformations -based on histologic and clinical presentation. For example, hemangiomas are characterized histologically by endothelial hyperplasia and increased numbers of mast cells during their proliferation phase. During the involution stage, they are characterized by fibrosis, fatty deposits, and multilaminated basement membrane formation beneath the endothelium. The mast cell count during the involution stage is similar to normal tissue, u