Port-wine stain. This unilateral vascular malformation has a markedly different histology, significance, and natural history from that of the salmon patch. The port-wine stain is made up of capillary ectasias that may be present throughout the dermis and that gradually increase with age. The color changes from pink to purple as the patient grows, and the lesions may become nodular during adult life. Because port-wine stains show no tendency to involute, they may represent a significant, lifelong cosmetic problem.