Zosteriform lichen planus.

A 95-year-old woman presented with a 4-month history of a pruritic eruption involving her trunk, medial thighs, and lesions limited to the C5 dermatome of the left upper extremity. Punch biopsy supported a clinical diagnosis of zosteriform lichen planus. Linear lichen planus refers to lichen planus with a unilateral linear distribution. This variant may present as an example of the Wolf isotopic response, or more rarely, a de novo eruption on previously-normal skin. In very rare instances linear lichen planus presents in a segmental fashion corresponding to a dermatome and is termed zosteriform lichen planus.