A 5 year old child who has not had routine pediatric care develops a febrile disease with cough and a blotchy rash, and is brought to the emergency room. On physical examination, there is cervical and axillary lymphadenopathy.Also noted is an erythematous, maculopapular rash behind the ears and along the hairline, involving the neck and, to a lesser extent, the trunk. Examination of this patient's oropharynx would likely reveal which of the following lesions?

The disease described is measles (rubeola), which has the typical presentation described in the question stem. Measles is caused by a Morbillivirus, an RNA virus belonging to the Paramyxovirus family. Koplik's spots, which are pathognomonic for measles, are small, bluish-white spots on the buccal mucosa in the early stages of measles. These lesions appear just before the onset of the characteristic rash (which can also involve the extremities) and fade as the rash develops. Leukoplakia is a premalignant condition characterized by adherent whitish patches on the gingiva and other sites in the oral cavity. Cold sores of the lips are due to infection with herpes viruses. Candida infection (thrush) produces curdy white material loosely attached to an erythematous base. Ref: Ray C.G., Ryan K.J. (2010). Chapter 10. Mumps Virus, Measles, Rubella, and Other Childhood Exanthems. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.