[Klippel-Trenaunay syndrome and phacomatoses]

Several mechanisms can be invoked in order to explain the appearance in a limb of the characteristic triad : naevus, varices and osteodystrophy. Many cases can be explained by the haemodynamic disturbance associated with venous hypertension caused by a venous malformation combined with arteriovenous microcommunications. These are the true Klippel and Trenaunay Syndromes. In a few rare cases the haemodynamic disturbance is caused by one or more arteriovenous fistulae with major flows. These are the Parkes-Weber-Syndromes. Finally, in the more complex syndromes there is the combined triad of naevus, varices and osteodystrophy, together with other genetic disturbances. These are the Phacomatoses.