Multiple lesions of psoriasis circumscribed to those of systematized epidermal nevus occurred in a 31-year-old Japanese woman. She has had extensive verrucose or hyperkeratotic, brownish lesions on the distributional areas of cutaneous sensory nerves originated from the spinal cord C6-Th4 and L3-S1 over the right half of her body since birth. Psoriatic lesions first appeared on the brownish lesions at the age of 7 years. Microscopic sections of the psoriatic lesion revealed the same findings as lesions of ordinary psoriasis, losing the histologic features of epidermal nevus. A definite isomorphic response was evoked not only on lesions of epidermal nevus, but also on the apparently normal skin, following a skin abrasion, although most psoriatic lesions had disappeared with parenteral methotrexate therapy.
Sugai T, Shimotoge M, Saito T. Psoriasis and Systematized Epidermal Nevus. Arch Dermatol. 1970;102(6):656-660. doi:10.1001/archderm.1970.04000120074014