My experience: For cyst on back of neck, applied organic tea tree oil to location with a Q-tip, a few times per week and cyst is shrinking, almost flat now - Amazingly after 30 years!!!!
Tea Tree Oil
I had a keloid cyst on my thumb at the base of the nail, about the size of a split pea. I put a few drops of Tea Tree oil on and kept it covered with a bandaid for a day (to keep the oil in place). Nothing happened for many weeks, but then it started flaking off gradually.