Inclusion Criteria:  18 - 69 years of age Psoriasis vulgaris Skin type I - III Minimal surface of lesion of 3 cm2 Contralateral psoriasis vulgaris lesions located on chest, back, or upper legs  Exclusion criteria  A potential subject who meets any of the following criteria will be excluded from participation in this study if:  The participant uses other treatments (than laser therapy) during the study or two weeks before the start of the study that are known to affect psoriasis The participant suffers from any known neurological, vascular, or immunological condition other than psoriasis. The participant is allergic to lidocaine