Nevus Araneus (Spider Nevus) Workup

Updated: May 11, 2018
  • Author: Sarah Sweeney Pinney, MD, FAAD; Chief Editor: Dirk M Elston, MD  more...
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Laboratory Studies

Evaluate patients with extensive spider angioma (nevus araneus) lesions for underlying liver disease or for pregnancy, depending on the clinical context.


Other Tests

Confirm the diagnosis of spider angioma (nevus araneus) by observing the classic refill pattern from the central vessel outwards. This refill pattern is seen following compression and release of the lesion. Usually, no other testing is required.



In the rare cases when the diagnosis of spider angioma (nevus araneus) is questionable, consider skin biopsy to exclude basal cell carcinoma or other conditions, particularly if the lesion is enlarging.


Histologic Findings

The 5 basic components of the spider angioma (nevus araneus) are (1) an arterial net, (2) a central arteriole, (3) a thin-walled ampulla, (4) efferent spider vessels, and (5) capillaries. [1]

The central ascending arteriole ends in a thin-walled ampulla just below the epidermis. This ampulla feeds small arterial branches that radiate in an outward fashion into the superficial dermis. Glomus cells have been reported in the wall of the central arteriole. [1]