Get that swollen node checked. Back in 1996 was when I noticed the same thing. The doc said, "Let's take it out and see, but it is probably nothing." It was something......and that something led to months of radiation, many turns with high-dose chemo, and the bone marrow transplant. GET IT CHECKED !!!
Turns out the swollen lymph node was because I was sick. It developed right before I got tonsilitis and it has gone away now that I'm on antibiotics. If it comes back and it doesn't have anything to do with being sick, than I'll probably look into it.
My dad, who's always concerned about people's ailments and has had cancer and a stem cell transplant and the whole nine yards, thinks that the thing in my arm is probably just a cyst and is actually fairly commonplace, but it's worth keeping an eye on.