Small, hard blue lump on back of hand - any ideas what it could be??

[VotePedroPony]

Any suggestions welcome

This morning I've noticed a small (like a small pea size) blue-ish lump on the back of my hand. It looks like it's on/in a vein, and is where I had a cannula about a month ago.

Should I bother a doctor with this? It doesn't hurt unless I poke it about. Getting an appointment at our surgery is a nightmare, I'd have to get an emergency one to be seen this side of Christmas, and I obviously don't want to waste one. Just can't quite shake the feeling that a lump in a vein could potentially be sinister??

I had a similar lump on finger. left it for a while then mentioned it to a dr when I went with something else. He thought it was a vein. It stayed about 6 weeks or more then disappeared. it was sore to touch.