Psoriasis is a chronic, autoimmune disease that primarily involves the skin. Most people living with psoriasis have plaque psoriasis, which is characterized by “plaques”, or raised, red areas of skin covered with a silver or white layer of dead skin cells referred to as “scale”. Plaque psoriasis is the most frequently occurring type of psoriasis. The psoriatic plaques can appear on any area of the body but most often appear on the scalp, knees, elbows, trunk, and limbs, and the plaques are often itchy and sometimes painful.

Plaque psoriasis patients often have plaques in areas that are difficult to treat such as skin folds (intertriginous regions) or the scalp, which presents a challenge for drug delivery, as the creams and ointments typically used to treat psoriasis on other body areas can be challenging to apply in these areas. Furthermore, skin folds tend to have thinner, more easily irritated skin and are more prone to steroid-related side effects, especially skin atrophy (thinning), striae (stretchmarks) or telangiectasia (spider veins). Even with biologic therapies, plaques on the elbows and knees are often the last areas to resolve.