Koplik's spots

Koplik's spots are bluish-white spots seen on the buccal mucosa (mucous membrane of the inside of the cheek) of the mouth and are pathognomonic of measles. They are named after Henry Koplik (1858-1927), an American pediatrician who first described them in 1896.

They often appear a few days before the rash arrives and can be a useful sign to look for in children known to be exposed to the measles virus.