There are different types of psoriasis and different degrees of plaque psoriasis. With a mild case of plaque psoriasis, the lesions affect less than 2 percent of the body. (One percent of your skin is the size of your palm.)
A moderate case of plaque psoriasis is when people have 3 to 10 percent of the body affected by the raised, red lesions. If someone has plaque psoriasis over more than 10 percent of their body, this is considered a severe case. Also, a severe case of plaque psoriasis can be when the condition interferes with your quality of life. Even if the psoriasis is on 2 to 5 percent of the body, it it's on your feet or hands, it may affect you greatly.