[Classification of vascular anomalies (tumours and malformations). Clinical characteristics and natural history].

Vascular anomalies are divided into tumours and malformations. Haemangiomas are the most frequent amongst the former. Not normally present at birth, except in a premonitory form, they grow for 10-12 months due to hyperplasia, to subsequently undergo a progressive involution for a period that might last from ten to twelve years. They have an incidence of up to 12% in newborns; they are more common amongst girls; and are divided into superficial, deep and compound. Congenital haemangiomas and those that do not undergo involution are considered to be rare entities. Vascular malformations, with a lower incidence than haemangiomas, are always present at birth, they grow by hypertrophy and never undergo involution. According to the classification of the ISSVA, vascular malformations are divided - depending on the vessel affected - into capillary or venular (port-wine stain), venous, lymphatic, arteriovenous and combined or complex. Each of these has certain defining clinical and haemodynamic peculiarities. Within the final group are included some with a low flow, such as the Klippel-Trenaunay syndrome (venous and lymphatic venular vascular malformation associated with the muscular-skeletal hypertrophy of an extremity), and others with a high flow, such as the Parkes-Weber syndrome.