Red rash on the back.

Previously published Photo Quizzes are now featured in a mobile app. Get more information at http:/www. aafp.org/afp/apps. A 44-year-old man on active duty in the Marines presented with a dry, red patch of skin on his back that had been present for two days. The rash was pruritic and painful to touch. There was no discharge from the lesion. The patient did not have fever or new environmental contacts. He had not been carrying constrictive or heavy gear on his back, and he was not using any new soap or laundry detergent. His medical history was significant for a myocardial infarction several years earlier. Six weeks prior to presenting with the rash, he had coronary stents replaced in a five-hour procedure. Physical examination revealed a single, nonraised, rhomboid-shaped area inferior to the right scapula (Figure 1). The erythematous lesion was well demarcated. There was a visible capillary break with petechiae 1.5 cm inside of the borders. The central portion of the lesion had a fine scale. There were no other lesions or physical findings.