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.
Procedures
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]
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Large spider angioma on the left cheek of a child.
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The spider angioma has been compressed and is refilling rapidly from the central vessel.
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A spider nevus consists of a central arteriole with radiating thin-walled vessels. Compression of the central vessel produces blanching and temporarily obliterates the lesion. When released, the threadlike vessels quickly refill with blood from the central arteriole. The ascending central arteriole resembles a spider's body, and the radiating fine vessels resemble multiple spider legs.
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Multiple spider angiomas in a patient with cirrhosis.
