A 38-year-old man presents to his GP with persistent scaly plaques on his elbows and knees. He reports mild itch, occasional cracking and bleeding, and is self-conscious about the appearance. He has a positive family history for psoriasis and is a current smoker. Examination reveals well-demarcated erythematous plaques with silvery scales on the extensor surfaces of the elbows, knees, and scalp. He is otherwise systemically well. A diagnosis of chronic plaque psoriasis is made. The patient has not used any regular treatments before.