Procedures
Nevus anemicus can be distinguished from various segmental hypomelanoses, such as vitiligo and hypochromic nevi, by diascopy (ie, by applying pressure with a glass slide to the lesion and adjacent unaffected skin). With diascopy, nevus anemicus becomes indistinguishable from the surrounding skin, which is now blanched from the pressure of the slide. Loss of melanin does not occur in the lesion. Wood lamp examination does not accentuate nevus anemicus and may make the lesion inapparent, unlike true depigmenting disorders. The application of friction, cold, or heat does not produce changes within the lesion. Thus, scratching a line across both the lesion and normal surrounding skin will produce erythema in the normal skin but not within the lesion.
Histologic Findings
The histology of nevus anemicus is normal, and melanocytes are preserved and normally distributed. Electron microscopy fails to detect abnormalities in the vascular structure.
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Irregularly shaped, well-demarcated, asymptomatic hypopigmented patch of nevus anemicus on the lateral leg.
