Spider Naevi

Spider angiomas are due to failure of the sphincteric muscle surrounding a cutaneous arteriole.
The central red dot is the dilated arteriole and the red "spider legs" are small veins carrying away the freely-flowing blood. If momentary pre

ssure is applied,
it is possible to see the emptied veins refilling from the centre. No other angiomas show this phenomenon.
The dilation, in turn, is caused by increased estrogen levels in the blood.
• Many pregnant women,
• or women using hormonal contraception, have spider angiomas, due to high estrogen levels in their blood.
• People who have significant hepatic disease also show many spider angiomas, as their liver cannot detoxify estrogen from the blood, resulting in high levels of estrogen
About 33% of patients with cirrhosis have spider angiomas. As such, microhemorrhages may be observed as spider angiomas.