Spider nevus (also known as spider angioma, spider naevus, nevus araneus, or vascular spider) is a common, benign skin lesion characterized by a small, bright red central spot (representing a dilated arteriole) with thin, radiating blood vessels extending outward like spider legs, creating a web-like or star-shaped appearance typically 1–10 mm in size. These often appear on the face, neck, upper chest, or arms and are usually painless and non-itchy; they blanch (turn pale) when pressure is applied to the center and refill quickly upon release. While solitary ones are harmless and common in healthy children or adults (affecting 10–15% of people), multiple spider nevi can signal underlying conditions such as liver disease (e.g., cirrhosis), hormonal changes (pregnancy or estrogen use), or rarely other issues like malnutrition—though many occur without any known cause. Treatment is rarely needed unless for cosmetic reasons, but options include laser therapy or electrocautery if bothersome; consult a doctor if new or numerous ones appear suddenly.