Test your diagnostic skills in our regular dermatology quiz. What is the cause of the erythematous, hot and itchy rash on this man’s forearms?
A 70-year-old man presents to hospital with peripheral lower leg oedema. He has metastatic pancreatic carcinoma and recently completed his first round of chemotherapy.
On admission, the patient is given an immediate dose of hydrochlorothiazide 100mg. Three days later he is noted to have a rash on his forearms that evolves into hyperpigmentation (Figure 1). The rash is erythematous, hot and itchy and associated with mild oedema. It has a sharp cut-off at the edge of his pyjama sleeve and the skin under his watch is spared.