A 68-year-old Caucasian woman presents with an eight-year history of an erythematous, pruritic and scaly rash over her central chest, upper back and forearms.

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<p>A 68-year-old Caucasian woman presents with an eight-year history of an erythematous, pruritic and scaly rash over her central chest, upper back and forearms.</p><p>This is on a background of breast cancer, which was managed with lumpectomy and radiotherapy, resulting in significant post-radiation dermatitis on her right breast.</p><p>She also has type 2 diabetes, hypertension, asthma and hypercholesterolaemia, which are managed with metformin, glimepiride, exenatide, perindopril, fluticasone propionate, salmeterol, salbutamol and rosuvastatin.</p><p>On examination, there are well demarcated erythematous macules and erosions on her upper chest (pictured), upper back and forearms. She has tried clotrimazole for two months with no improvement.</p>

Professor Dédée Murrell is head of dermatology at St George Hospital, professor at UNSW Sydney, and honorary professorial fellow at the George Institute for Global Health, Sydney.