What are spider angiomas? Why are they associated with liver disease?
Spider angiomas (nevus araneus) are vascular lesions characterized by a central arteriole and horizontal radiating thin-walled vessels that produce the legs of the vascular spider. The pulsation of the central, vertically oriented arteriole in larger lesions can be visualized with diascopy (observing the lesion through a glass slide firmly pressed on the lesion). The pathophysiologic mechanism is not proven, but the high incidence of spider angiomas in alcohol-associated hepatitis and pregnancy suggests that elevated levels of estrogens resulting from higher production or decreased metabolism is responsible. Patients with liver cirrhosis and spider angiomas have elevated plasma levels of vascular endothelial growth factor, which may play a role in the development of spider angiomas.