Small, grain-of-sand sized, irregular, bright red spots with blue-white centres, occurring on the inside of the cheek (buccal mucosa). Seen only on measles (rubeolae) they are, by themselves, a diagnostic sign in measles. The spots usually occur briefly after the fever begins and a couple of days before the generalized rash appears. Not infrequently, the spots disappear as the eruption develops.
The first description of these spots by some authors are ascribed to Reubold, Würzburg 1854, by others to Johann Andreas Murray (1740-1791). Before Koplik, the German internist Carl Jakob Adolf Christian Gerhardt (1833-1902) in 1874, the Danish physician N. Flindt in 1879, and the Russian Nicolai Feodorowitsch von Filatov (1847-1902) in 1897, had observed equivalent phenomena.
- H. Koplik:
The diagnosis of the invasion of measles from a study of the exanthema as it appears on the buccal mucous membrane.
Archives of Pediatrics, New York, 1896; 13: 918-922.