Port wine stain, also known as nevus flammeus, is an abnormal dilation of capillaries, with an incidence of 3‰ in neonates. Port wine stains can be pink, red, light purple, and dark purple in their different development stages, and can develop into vascular nodules protruding from the epidermis in the late stage. 83% of port wine stains are on the head and neck and distributed along the trigeminal nerve. Most port wine stains are congenital, but trauma or surgery can also lead to acquired port wine stains.
The etiology of port wine stains is unclear, but studies have shown that the vascular region of port wine stains lacks the innervation of neurites. Normal blood vessels are innervated by sympathetic nerves, and sympathetic nerves continuously release low levels of adrenaline to maintain vasoconstriction. Therefore, defects in neuronal innervation can result in a lack of baseline level of vasoconstriction, resulting in gradual vasodilation. Studies have shown that changes in small molecules of guanosine triphosphate (GTP) enzymes or related proteins, such as gene mutation of RAS p21 protein activator 1 (RASA1) and guanine nucleotide-binding protein G(q) subunit alpha (GNAQα), may be associated with the pathogenesis of port wine stains. The up-regulated expression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGF-R2) in port wine stains suggests that VEGF and its receptor signaling pathway may play a role in vasodilation.
Signs and Symptoms
Port wine stains often occur at birth or shortly after birth, and are common on the neck and head, mostly unilateral, rarely bilateral, and sometimes the mucous membranes can be involved. Skin lesions are flat plaques composed of numerous dilated capillaries, and the size of the skin lesions increases correspondingly with the growth of the body. Ophthalmic and maxillary nerves may be involved.
Figure 1 port wine stains
Histologically, port wine stains present dilation of capillaries and postcapillary venules, often in the papillary and reticular layers of the dermis. The vessel diameter in the port wine stains are 10 - 150μm, up to 500μm.
On the basis of typical clinical presentations, the disease can be diagnosed.
Laser is the optimal treatment. Pulsed dye laser, Nd:YAG laser, KTP laser, alexandrite laser, CO2 laser, and intense pulsed light can be applied, and photodynamic therapy is appropriate.
If there are nodules, surgical excision may be required.