Disseminated superficial "actinic" porokeratosis.

The dramatic therapeutic response of disseminated superficial actinic porokeratosis (DSAP) to retinoid plus psoralens with ultraviolet A prompted a review of clinical, histologic, and etiologic data of all of the DSAP cases available in the English and German literature. The review showed that many case reports lack adequate documentation to confirm actinic induction. More than one third of the patients have observed no exacerbations during the summer. Histologic damage after long-term ultraviolet (UV) exposure could not be observed in every case. In addition, cases do exist in which lesions are distributed mainly in non-UV-exposed skin. These data cause doubt about the importance of actinic induction of DSAP.