• In 21 of 38 cases of proved and one case of probable infectious mononucleosis petechial eruption on the soft palate was observed. The eruption consisted of multiple pin-point lesions on the soft palate, usually near the junction with the hard palate but sometimes near the midline more posteriorly. In one patient the petechiae were also noted on the uvula. The number varied from 10 to several hundred. They appeared from 3 days to two weeks after the onset of symptoms, lasted from 3 to 11 days, and then faded, leaving no trace. In two cases in which platelet counts, capillary fragility tests, and clot retraction tests were done, there was no sign of a hemorrhagic diathesis. This eruption was primarily responsible for an early, correct diagnosis of infectious mononucleosis in two instances.
Shiver CB, Berg P, Frenkel EP. PALATINE PETECHIAE, AN EARLY SIGN IN INFECTIOUS MONONUCLEOSIS. JAMA. 1956;161(7):592–594. doi:10.1001/jama.1956.02970070024006