1813, from Modern Latin, from aknas, a 6c. Latin clerical misreading of Greek akmas, accusative plural of akme "point" (see acme). The "pointed" pimples are the source of the medical use.
acne ac·ne (āk'nē)
n.
An inflammatory disease of the sebaceous glands and hair follicles of the skin that is marked by the eruption of pimples or pustules, especially on the face.