1. William M. Stauffer, MD, MSPH, DTM&H* 2. Angela D. Siwek, MD† 3. Deepak Kamat, MD, PhD‡ 4. Erika Kempler-Meyer, MD§ 1. *Center for International Health & International Travel Clinic, Regions Hospital, Pediatric Emergency Medicine, University of Minnesota, Minneapolis, MN 2. †Department of Pediatrics, University of Minnesota, Minneapolis, MN 3. ‡Director, Institute of Medical Education, Children’s Hospital of Michigan, Detroit, MI 4. §Doernbecher Children’s Hospital, Oregon Health & Science University, Portland, OR A 14-year-old boy presents with rash, fever, chills, and difficulty walking due to right hip pain. The patient had been healthy until 2 weeks ago when he developed muscle pain, headaches, sore throat, cough, and decreased appetite. Ten days ago, he was started on a course of azithromycin for “bronchitis.” Rapid streptococcal antigen and mononucleosis antibody tests were negative at that time. Three days later, the antibiotic regimen was changed to a second-generation cephalosporin for a presumed urinary tract infection after red blood cells appeared in the urine. Urine nitrite and leukocyte esterase were negative. Three days later (and 4 days prior to presentation), the patient developed right shoulder pain, fever, “sores” in his mouth, blood-streaked sputum, frequent episodes of nosebleeding, “pain with deep breaths,” a rash on his lower legs, and sore and swollen feet. At that time, his white blood cell (WBC) count was 5.2×103/mcL (5.2×109/L), with a normal differential count; findings on chest radiograph were normal. The patient currently has difficulty walking due to right hip pain. He denies any history of exposure to infectious diseases. The boy’s past medical history is remarkable for a ventricular septal defect (VSD) discovered during early infancy. He has received prophylaxis against bacterial endocarditis before every dental procedure. His growth and development are normal, and he has no allergies to food or medicine. His immunizations are up to date, and current medications include cefprozil, acetaminophen with codeine, and ibuprofen. He is in eighth grade, lives with his parents, and has no siblings. He denies sexual activity and use of tobacco, alcohol, or drugs. On physical examination, the patient appears pale and weak. His temperature is 101.3°F (38.5°C), blood pressure is 135/78 mm Hg, respiratory rate is 22 breaths/min, and heart rate is 104 beats/min. Raised, red-purple, nonblanching …