Recently, I have just noticed a bump/lump on the back of my hand/wrist. It's been itchy since last night. Is this anything to worry about?

Ganglion--no problem. Most likely, this is a ganglion, which is a fluid filled cyst. It is very common and usually is left alone. If it continues to cause pain or symptoms it can be aspirated (fluid sucked out), ruptured (usually injected with numbing medication and steroid to cause it to rupture), or removed surgically. These have approximate long term success rates of 60%, 85%, and 95%, respectively.