[Vascular malformations (I). Concept, classification, pathogenesis and clinical features].

Vascular malformations are anomalies always present at birth that, contrary to hemangiomas, never regress and may grow during lifetime. Clinical presentation of vascular malformations is extremely variable and ranges from asymptomatic spots of mere aesthetic concern to lesions with high blood flow or located in critical sites that may be life-threatening. Given the low incidence of these disorders it is difficult to establish therapeutic guidelines. In addition to a correct classification of vascular anomalies, it is necessary a multidisciplinary approach for the follow-up and management of these patients. The first part of this review focuses on the different classifications of vascular anomalies, maintaining as reference the one proposed by the International Society for the Study of Vascular Anomalies (ISSVA). Additionally, clinical features of the different subtypes of vascular anomalies as well as their association in certain syndromes are reviewed.