Cervicofacial vascular anomalies. II. Vascular malformations.

Vascular malformations are the second major category of vascular anomalies. In contrast to vascular tumors, they are present at birth and grow commensurately with the child. Although the molecular mechanisms underlying the formation of these lesions remain unclear, lesions are known to result from abnormal development and morphogenesis. Histologic examination of vascular malformations shows no evidence of cellular proliferation, but rather progressive dilation of abnormal channels. Vascular malformations are designated according to their predominant channel type; they may be capillary, venous, lymphatic, arterial, and combined malformations. Malformations with an arterial component are rheologically fast-flow, whereas capillary, lymphatic, and venous malformations are slow-flow in nature. The morbidity of vascular malformations varies greatly both within and among the clinical subgroups cited above. This article describes the clinical presentation, diagnosis, and management of vascular malformations. The more frequently encountered clinical presentations involving the head and neck are highlighted.