Department of Dermatology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221002, China.

Introduction An isotopic response is the occurrence of a new skin disease at the site of another, unrelated, healed skin disorder. In 1955, Wyburn-Mason reported 26 cases of nonmelanoma skin cancer occurring at sites, which were previously affected by herpes zoster[1]. Forty years later, Wolf and colleagues coined the term "isotopic response" to describe this phenomenon[2]. Here, we report an isotopic response of psoriasis vulgaris in an immunocompetent patient, occurring on the area of a resolved herpes zoster lesion on the trunk. Diagnosis was made based on the clinical and histological findings.