Sounds like the ganglion I had removed from my ankle. It was the size of a walnut and there was no pain, but I wasn't a fan of huge lumps sticking out of the side of my leg. We gave it a couple months to go away, tried some ketoprofin to see if something inflamed was causing it (nope), so I said go ahead to the surgery. Only took a couple hours but I was on crutches for a month or so which was rather inconvenient. I could have let it go, but eh, that's what medical insurance is for.
