(nevus flammeus) A congenital vascular malformation consisting of superficial and deep dilated capillaries in the skin which produce a reddish to purplish discolouration of the skin.

(port wine stain) A congenital vascular malformation in the skin (birthmark) characterized by the presence of dilated capillaries. The affected area of the skin is flat and reddish-purplish in color.

A vascular malformation of developmental origin characterized pathologically by ectasia of superficial dermal capillaries, and clinically by persistent macular erythema. In the past, port wine stains have frequently been termed capillary hemangiomas, which they are not; unfortunately this confusing practice persists: HEMANGIOMA, CAPILLARY is neoplastic, a port-wine stain is non-neoplastic. Port-wine stains vary in color from fairly pale pink to deep red or purple and in size from a few millimeters to many centimeters in diameter. The face is the most frequently affected site and they are most often unilateral. (From Rook et al., Textbook of Dermatology, 5th ed, p483)

Port-wine stains are flat pink, red, or purplish discolorations present at birth due to malformed blood vessels. Port-wine stains are harmless, permanent discolorations. However, their cosmetic appearance may be psychologically bothersome or even devastating. They appear as flat pink, red, or purple patches of skin. Port-wine stains may...