Test your diagnostic skills in our regular dermatology quiz. What is the cause of the severe blistering eruption on this elderly man’s ankle and foot?
A 75-year-old man presents with a severe blistering eruption on his ankle and foot (Figure 1). He recently suffered a small cut on the ankle and began to self-treat it with a herbal cream containing rhus extract. Four days later the eruption developed. It is intensely itchy and is starting to appear on other parts of his body, including the skin on his face and penis.