How do I know if this is a cyst or a contagious wort? They look exactly the same, apparently.

I also have a few of these. I had one on my middle finger between the cuticle and the joint, but no arthritis in that finger. I was full of clear gel and would rupture and regrow. My dermatologist called it a wort caused by bacteria and froze it. I googled "blister wort" and found someone with them all over the backs of their hands, and looked very similar to mine, but it also looks exactly like the mucous cysts. I went back for 5 freezes on that same location over a few months. Finally, it quit coming back. That was about a year ago. Now I have one on my index finger on top of my arthritis knob. I went back to my dermatologist, and this time he called it a cyst and a wort in the same sentence. He froze it, and it didn't really go away. I hate the liquid nitrogen, it's painful and leaves you with a nasty sore that lasts for a weeks, so I decided to try to handle it on my own. I used the duct tape treatment that works for other types of worts, and after about 3 weeks of that it got smaller but hasn't gone away. I also have another one on my other index finger which also has an arthritis knob. I am currently trying soaking my finger in Epsom salt water, and I will also try the various ointments that I have seen here. If none of that works, it's back to Mr. Freeze.