Editorial
All congenital vascular malformations should belong to one of two types: “truncular” or “extratruncular”, as different as apples and oranges!

Congenital vascular malformation represents a group of anomalous vascular structures caused by defective development through various stages of embryogenesis. In 1988 a workshop for this unique field of vascular pathology was held in Hamburg, Germany, and new classification was evolved on the basis of consensus through this workshop. Congenital vascular malformations are now classified based on their predominant vascular components, namely: arterial malformations, venous malformations, lymphatic malformations, capillary malformations, and arteriovenous malformations. The majority of congenital vascular malformations exist alone as independent forms, but infrequently the malformation can exist as a combined form. Depending on the embryological stage at which the defective development occurs, all congenital vascular malformations present with one of the two distinctive characteristics that originate from the embryological background. Congenital vascular malformations originating from an early stage of embryogenesis are classified as extratruncular lesions, while those with developmental arrest at a later stage of embryogenesis, no longer exhibiting the evolutional potential to grow, are referred to as truncular malformations. In addition to the embryonic characteristics of the malformation that depend on “evolutional potential” originating from the mesenchymal cells, each malformation also has its unique haemodynamic characteristics. Clinically relevant haemodynamic impact is especially found among truncular lesions, such as marginal vein or fistulous arteriovenous malformations.