Why do spider angiomas appear in cirrhosis?

The main reason for the appearance of spider nevi in cirrhosis lies in the significant decline in liver function. Since the liver is responsible for inactivating estrogen, cirrhosis causes impaired liver function, thereby weakening the inactivation of estrogen and resulting in elevated estrogen levels in the blood. Estrogen has the effect of dilating small arteries, which leads to arterial dilation within the drainage area of the superior vena cava. This results in the typical appearance of spider nevi on the skin, characterized by a central small red spot with surrounding radiating, spider-like blood vessels. Additionally, as liver function changes, the color and presence of spider nevi may also change, representing a distinctive manifestation of declining liver function.