Comparative morphometric study of eruptive PUVA-induced and chronic sun-induced lentigines of the skin.

Computerized image analysis was used to compare lentigines (brown freckle-like cutaneous spots) induced by treatment with psoralens and ultraviolet light A (PUVA-induced lentigines) with those induced by solar exposure (actinic lentigines). For these conditions, which appear to be distinctive clinically and histologically, the number, size and shape of the macules were analyzed, revealing significant differences in the two latter parameters. This indicates that UV irradiations of different wave lengths act differently on melanocytes and/or on the interrelation between melanocytes and keratinocytes. The overall effect is much more self-limited in PUVA lentigines than in actinic lentigines, suggesting that the pathophysiology of these lesions is probably different.