Psoriasis is an auto-immune condition that affects the skin cells, which means the body’s own immune system mistakenly attacks them. If someone has psoriasis, their skin cell lifecycle is expedited, which causes rapid cell build up on the skin’s surface in the form of red, itchy, dry, and sometimes painful scales or lesions. The most common areas for lesions to form are the elbows, knees, scalp, chest, and lower back. Psoriasis can also affect the joints, called psoriatic arthritis, though the most common type of psoriasis is plaque psoriasis. Treatment options depend on the severity and number of the lesions and what areas of skin are affected.