A case of segmental vitiligo occurring where herpes zoster occurred previously as an isotopic response

Wolfs isotopic response is defined as the occurrence of a new skin disorder at the site of another unrelated skin disease that has already healed. In most cases of isotopic response, the initial dermatosis is herpes infection, and the most frequent second dermatoses are granulomatous reactions. Various interpretations of this phenomenon have been attempted. However, the exact mechanism has not been identified yet. Herein, we report a case in which the secondary disease was segmental vitiligo that appeared over the same dermatomes of herpes zoster. A 71-year-old woman presented with well-defined, depigmented patches on the left chest and back. She had been diagnosed with herpes zoster on the same dermatomes and treated with an antiviral agent 3 years ago. Histological examination showed decreased basal melanin pigments and melanocytes. Consequently, the patient was diagnosed with segmental vitiligo based on the clinical and histological findings.