A 3 year old child is seen by a pediatrician because he has developed multiple isolated lesions on his face and neck. Physical examination reveals many lesions up to 4 cm in diameter with golden crusts, while in other sites small blisters and weeping areas are seen. Which of the following is the most likely diagnosis?

This is impetigo, which is typically seen in preschool children with poor hygiene, paicularly in the summer in warm climates. The characteristic lesion has a large golden crust. Most cases are caused by Staphylococcus aureus; Streptococcus pyogenes is occasionally implicated. Impetigo is highly infectious, and mini-epidemics can occur in daycare settings. The initial treatment is typically with penicillins and topical preparations. Methicillin-resistant strains are presently rare in this setting, but can occur. Aphthous ulcers commonly known as "canker sores," are painful, shallow ulcers of the oral cavity. Erysipelas is a different type of skin infection, often caused by Streptococcus pyogenes (also sometimes others including Staphylococcus), and is characterized by large erythematous patches. Herpes simplex I causes tiny oral and perioral vesicles, but not large golden crusts. Ref: Morelli J.G., Prok L.D. (2012). Chapter 15. Skin. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.