Test your diagnostic skills in our regular dermatology quiz. What has caused this polymorphic bullous eruption on an older man’s legs?
A 68-year-old man is referred to the hospital emergency department by his primary care physician with worsening bullae on both legs (Figures 1a and b). He had a fall one week earlier in his backyard and is unsure how long he was immobilised. He does not recall any injuries after this event, but that evening he noticed a blister on the instep of his right foot. He was initially treated with cephalexin, but over the next few days he developed further bullae across both legs, which easily burst. These bullae are not associated with significant pain or pruritus and he has not used any other new medications. He has a medical history of atrial flutter and type 2 diabetes which is treated with insulin. His social circumstances are poor.