I'd had a cyst on my right hip since back in the late 70s or early 80s. The doctor told me not to worry about it unless it became troublesome, and a couple weeks ago it became troublesome (sore & swollen). My doctor said it was infected, put me on antibiotics and said he'd remove it for me - no big deal. Simply a small incision (about 1/2") and pop it out.
Well, it turned out to be way more than he planned.
Turned out there was so much scar tissue built up around it that it was firmly attached and he ended up making a 3-4" incision to get it dug out. The chunk of cyst, scar tissue, and meat he removed was about the size of a walnut! 
Good news - no problems with it (such as cancer). Bad news - I'm going to need a day or two longer than planned before I can get back to doing much. It's even interesting to figure out a way to get settled into my chair.
I've been telling close friends it was similar to removing a brain tumor based on size and location.
I see it's a good thing I did get in my chair and log in to the forum, though.
Now I can get all the best offers on selecting a new mattress if I bleed on my old one.
