Maya C. Myslenski, MD

A 10-year-old boy presents to your office with sharp right-sided flank pain. The pain began the night before, and the child could produce only a few drops of urine the next morning.

A 10-month-old boy with an asymptomatic rash is brought to your office by his mother. The rash, which began on the legs and spread to the arms, face, and buttocks, has been present for 3 days. Other than rhinorrhea and nasal congestion for the past 3 to 5 days, the infant has been well, although fussier than usual, especially at night. His appetite is normal. The rash has persisted despite the application of bacitracin, petroleum jelly, and cortisone. He has had no sick contacts with a similar rash or illness. His immunizations are up-to-date.

THE CASE: A 3-year-old boy is brought to the office by his mother. The previous evening, she had noticed a single large red spot on the back of his thigh. This morning, his whole body was covered with a similar rash, and he had a temperature of 38.8°C (102°F). The mother administered 1 dose of acetaminophen at home for the fever; the rash was asymptomatic.