Zosteriform lichen planus after herpes zoster: report of a new case of Wolf's isotopic phenomenon and literature review.

The Wolf's isotopic phenomenon corresponds to the occurrence of a skin disease at a body site affected previously by a different, already healed dermatosis. We report a 74-year-old man who presented with a zosteriform eruption consisting of erythematous-scaly, slightly pruritic papules on the right flank some weeks after herpes zoster (HZ) had healed on the same area. Histologic examination showed typical changes of lichen planus, confirming the diagnosis of post-HZ zosteriform lichen planus (ZLP). The lesions regressed with topical steroid treatment. Zosteriform lichen planus (ZLP) is one example of Wolf's isotopic phenomenon appearing after HZ. So far, only 17 cases have been reported in the literature. The precise pathogenesis of ZLP is not well known, although persisting viral proteins could be responsible for the hypersensitivity reaction. We review and discuss the salient clinicopathologic features of this rare entity based on a thorough literature review.