Eons ago, in the late '60's, I had one. My old fashioned nurse grandmother fixed it with a home remedy. She had me lay my hand flat on the table & she slammed it with a huge dictionary. It hurt,bruised my hand, but the cyst disappeared. I'd recommend going with a physician. Easier on the table. And with Google, who still has a big dictionary?
Goodness, your comments reminded me of when my mum had one on the back of her hand. It got rather large and she wanted rid of it, so she had her hand on the top of the bannister and she told me to hit it. Being only about 9 years old at the times she probably thought I wouldn't hit it too hard. So I got the dictionary and hit it as hard as I could. She was very surprised I'd hit it so hard. The outcome was it disappeared. She is now 96 and I'm 67 and we both remember it very well.