What is the difference between pustular psoriasis and plaque psoriasis? Although, plaque and pustular psoriasis can coexist or one may follow the other, the main distinguishing feature of pustular psoriasis is the appearance of pus spots surrounded by or on top of areas of red skin. This does not mean there is infection present. The spots simply show that the skin has been invaded by white blood cells. The person is not infected and neither are they contagious in any way.
Pustular psoriasis flare-ups can be triggered by some medicines, irritating substances on the skin, ultraviolet light overdoses, pregnancy, systemic steroids (especially sudden withdrawal of tablet or high-potency topical steroids), infections or emotional stress.