What is this hard lump on the palm of my hand?

More information. A hard lump on the palm on your hand is likely early dupuytren's nodule or a ganglion cyst. It is important to consult a hand surgeon for a full history and examination to determine the likely diagnosis.
See your doctor. You sould see your doctor. This lump needs to be palpated by your doctor and he/she needs to be able to put the rest of your symptoms in perspective.