Thread veins are red and purple blood vessels that occur in patches on the legs and face. They look like small spider webs, which is why they are also called spider veins. Another term for the same problem is naevi.
Spider veins (referred to medically as telangiesctasias) and varicose veins are not the same condition. Varicose veins are large, swollen veins usually affecting the legs whereas spider veins are delicate and tend to develop in clusters.
Spider Veins usually take on one of three basic patterns (see side photo A, B & C).
They may appear as thin seperate lines (A); they may resemble tiny branch-like shapes (B); or they may appear in a true spider shape with a group of veins radiating outward from a dark central point (C). Type A are commonly seen on the inner knee, whereas the branching pattern ussually appears on the outer thigh in a sunburst or cartwheel distribution.