Koebner phenomenon in xanthelasma after treatment with trichloroacetic acid.

A 47-year-old woman presented with a history of yellow plaques on her eyelids. These lesions had been diagnosed clinically as xanthelasma and treated five times with topical applications of trichloroacetic acid (TCA) 33 percent. Despite flattening of the original lesions, the patient noticed extension of the lesions on the site of treatment following each session. Skin biopsy showed characteristic findings of xanthelasma. It appears that, in rare instances, xanthelasma palpebrarum may progress following TCA application by a Koebner-like phenomenon.