Bumps at the wrist, the top of the fingertip, or at the base of the finger are known as ganglion cysts. These are pockets of fluid and are generally not harmful. A bump on your palm is likely dupuytren disease. This thickening of the palm may cause your fingers to bend.
Bumps or Cysts on the Arm
The majority (though not all) of bumps or lumps below the elbow are benign (not cancer), but all should be evaluated by a knowledgeable medical professional.