Plaque psoriasis, also known as vulgar psoriasis, is the most common form of psoriasis (80% of cases). The plaques tend to occur in a symmetrical fashion on the left and right, especially on the elbows and knees, and by extension on the arms and legs. Plaques vary in size but are always very well defined, with the healthy skin on one side and the very red and very scaly, inflammatory skin on the other side.
Summary
Elbows, knees, arms and legs, all these areas are frequently affected by psoriasis because they are areas subject to friction. Therefore, friction (caused by clothing, an activity, while asleep, etc.) can be considered as a skin trauma, just like stings, scratches and wounds, etc. and can lead to psoriasis flare-ups according to the Koebner phenomenon.
Psoriasis on the elbows and knees is very common, but it is not often "seen". Most of the areas affected by plaque psoriasis are usually conveniently hidden under clothing. When you have psoriasis on your elbows and/or arms, you tend to wear long sleeves. When you have psoriasis on your knees and/or legs, you tend to wear pants in summer and winter.
Yet psoriasis is neither contagious nor dirty. It can be treated but sometimes remains visible for several days or even several weeks. But this is not caused by a lack of hygiene or because the treatments are not effective! It's just that some plaques take longer to heal than others and treatment may take effect at varying speeds depending on the patient. Patients with psoriasis on the elbows and knees should not be afraid, or at all ashamed to roll up their sleeves, or show off their legs.
