A 56-year-old man, diagnosed with psoriasis three years ago, presents to your clinic with pruritus. His symptoms are not improving despite being prescribed conventional therapy. On examination, you note the presence of erythematous scaly plaques on the extensor surfaces of the knee and elbows. There is no evidence of flexural involvement. The most appropriate treatment is:

A. Topical retinoid therapy B. Topical tar preparations C. Topical steroid preparations D. Topical vitamin D analogue preparations E. Antibiotics

4. Nail changes

You are asked by your registrar to see a 45-year-old Caucasian woman with psoriasis who has presented with suspicious nail changes. Which one of the following nail changes are associated with psoriasis?