Petechia

Petechia (plural: petechiae) was a small red or purple spot that could present itself on a humanoid body, and was usually caused by a minor hemorrhage. Petechia could also resemble vacuum mottling.

During his preliminary examination of Crewman Scott Darnell's body following his death of planet M-113, Doctor Leonard McCoy thought that the mottling on Darnell's body resembled petechia. 


 * The novelization of the episode by James Blish, incorrectly spells the condition as petachiae.