Other Tests
Diascopy is useful for differentiating venous lakes from other lesions. Direct pressure created by a glass microscope slide causes a vascular lesion such as a venous lake to blanch as its contents are emptied. Sometimes, blood may not be completely emptied with diascopy, but a color change ensues. Cherry angiomas and neoplasms (ie, basal cell carcinoma or nodular melanoma) do not change color with diascopy.
Epiluminescence techniques such as dermoscopy also can be used to differentiate vascular lesions (eg, venous lake) from melanocytic neoplasms. A venous lake observed under the dermatoscope has a homogenous reddish-blue to reddish-black color and no pigment network structures.
A biopsy is indicated if the diagnosis of venous lakes remains in doubt.
Histologic Findings
In venous lakes, a single large dilated space or several interconnecting dilated spaces characteristically are observed in the superficial dermis. The dilated channels have very thin walls that are lined by a single layer of flattened endothelium and supported by a thin layer of fibrous connective tissue.
Usually, no smooth muscle or elastic tissue is found in the vessel wall. In rare cases, a thin and noncircumferential area suggestive of smooth muscle can be found instead of the fibrous tissue. Solar elastosis and other evidence of sun damage usually are found in the adjacent dermis.
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Venous lake on the helix of the ear.
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Venous lake on the lower lip.
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Venous lake of the lip. Note the apparent actinic damage of the surrounding skin. Courtesy of Albert C. Yan, MD.
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Venous lake becomes inconspicuous during diascopy with a glass slide.
