Psoriasis is a progressive disease, and it can occur on any part of the body. The patches associated with plaque psoriasis generally start off in small areas. Over time, as the disease progresses, separate patches may join together to form larger areas.
That being said, while psoriasis is a chronic condition, the patches can come and go. For most people with psoriasis, the disease will “flare up” periodically, triggered by things like the weather, infection, or stress. Knowing your triggers, and keeping stress to a minimum, can help to keep psoriasis at bay.