Observations
In addition to what the mother mentioned, discussion reveals that the child has been complaining of a headache, and that the cold-like symptoms preceded the rash by several days. Mother and child both deny the girl has had a sore throat. Exam reveals no lesions on the child’s body, and the child has not been taking any medication.
Diagnosis
While the differential includes scarlet fever, Kawasaki disease, and rubeola, the correct diagnosis in this case is erythema infectiosum. Also known as “fifth disease,” this is a common illness among young children and is due to infection with parvovirus B19. It can result in a mild exanthem, no exanthem, or (typically) a “slapped cheek” rash as seen in this image.
No treatment is indicated, as the infection will run its course and the rash should disappear in 1 to 3 weeks.