A previously healthy 20-year-old man presents with a mildly pruritic, progressive rash. The eruption began in his scalp and subsequently spread over 9 days’ time to his neck, back, and chest. He had been seen in the emergency department and prescribed oral cephalexin for the eruption, with no improvement. He denies any other use of medication (including prescription or over-the-counter medications, herbal supplements, and vitamins) in the days, weeks, or months prior to onset. He denies any travel or illicit drug use. The patient otherwise feels well, without fever, chills, or systemic symptoms. He has received appropriate immunizations, has no relevant family history, and has never experienced similar episodes. The physical examination is notable for numerous grouped vesicles and relatively monomorphic tense bullae, coalescing into markedly annular plaques, superimposed on erythematous bases with central clearing and scale. The eruption is generalized and symmetric but predominates on his posterior neck, back, chest and upper arms (Figure 1), and inner thighs. He is otherwise afebrile and appears well.
Johnson EF, Jacobs MH, Smidt AC. Annular Vesiculobullous Eruption in a Healthy Young Man. JAMA. 2013;310(23):2559-2560. doi:10.1001/jama.2013.283530