Test your diagnostic skills in our regular dermatology quiz. What is the cause of this symmetrical rash and the associated itchy papules on a patient’s hands and elbows?
Case presentation A 52-year-old farmer presents with a three-week history of a pruritic erythematous rash and associated pruritic papules on the extensor surfaces of his hands and elbows (Figure 1a). The rash, which is affecting his face (Figure 1b), chest and back, is violaceous and maculopapular and has a symmetrical distribution affecting photoexposed skin. He has also noticed progressive difficulty in performing farm duties, and especially walking uphill, due to weakness without pain or dyspnoea.