Torezan L, et al. - The effectiveness and safety of the combination of topical calcipotriol (CAL) before methylaminolevulinate (MAL)-photodynamic therapy (PDT) for actinic keratosis (AK) of the scalp were compared with the conventional MAL-PDT. For the treatment of AKs on the scalp, CAL-assisted PDT proved to be safe and more effective than conventional MAL-PDT. CAL pretreatment resulted in an increase in the accumulation of protoporphyrin IX (PpIX) within the skin and could have enhanced the efficacy in this first human trial.