Definition of venous malformations
VMs are developmental anomalies (birth defects)
of the venous system. They are the result of arrested
development of the venous system during the
various stages of embryogenesis. Together with
arterial, capillary and lymphatic malformations
they are part of a large group of congenital vascular
malformations (CVMs) which are developmental
anomalies of the peripheral vascular system.
These lesions are the result of the developmental
arrest that occurs during the “later” stages of
vascular trunk formation during the fetal development.
This arrest occurs long after the embryonic
(reticular) stage of vascular development is
over. These lesions are also known as “post-truncal
Truncular lesions, therefore, do not have the
embryonic characteristics of the mesenchymal
cells (angioblasts) as observed in the extratruncular
lesions. These lesions no longer possess the
critical evolutional ability to proliferate. The risk
of recurrence after treatment is minimal to none.
These lesions have hemodynamic consequences
due to congenital valvular incompetence, obstruction
(atresia, hypoplasia) or dilatation/aneurysm
formation with associated risk of thromboembolism.
Truncular VM lesions may also occur in veins
with the same embryologic origin or draining the
same territory (e.g., stenosing lesions of the
extracranial jugular veins, superior vena cava, and
azygos vein system along the main outflow pathways
of the cerebro-spinal venous system as suspected
cause of multiple sclerosis)
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