Morphologic changes in epidermis of PUVA-treated patients with psoriasis with or without a history of arsenic therapy

The uninvolved skin of patients with psoriasis was examined microscopically. Atypical nuclear features in keratinocytes and melanocytes were found in about half of the patients. The patients treated with psoralens and UV-A (PUVA) had significantly more of these changes than did patients without PUVA treatment, and the risk was dose dependent. Previous arsenic treatment and x-ray irradiation seemed to have a similar effect. The changes may have been due to the shortwave UV range of the light source.