Psoriasis is a chronic disease that affects the skin and joints. Clinical hallmarks comprise erythematous plaques covered by silvery scaling and a chronic recurrent course. Histologically, psoriasis is characterized by the hyperproliferation of the epidermis, elongated and prominent blood vessels and a thick perivascular lymphocytic infiltrate. Psoriasis is now considered an auto-immune disease. Although many different therapies are available, there is clearly a need for new treatments. Our improvement of understanding of the pathogenesis of psoriasis together with the possibility to develop bioactive proteins ("biologicals") targeted at specific steps in the pathogenesis of psoriasis, have opened a new field of promising future treatments. In the development and assessment of new therapeutical modalities for psoriasis, a clear definition of a patient's psoriasis severity is essential. The impact of a given therapy can only then be evaluated, based on the changes in the severity score during and after application of the treatment.
Copyright 2004 Blackwell Publishing, Inc.