 A calcipotriol-cream and a placebo cream are used in this study. Fifteen PLE patients will be enrolled. On day 1, the individual minimal erythema dose MED is assessed on patients skin by exposure to a test ladder of solar-simulated UVR produced by a xenon arc source Oriel Corp. Darmstadt, Germany. From day 2 to 5, 0.5 individual MED exposures increased by 0 to 30 per exposure, depending on the erythema response to a preceding dose are given to a total of four 10-by-10 cm skin test fields on symmetrically located, individual PLE predilection sites on the trunk or extremities. These test fields are pretreated in a randomized and double-blinded fashion either with the calcipotriol cream or the placebo cream twice a day during 7 days before start of phototesting. 