Sometimes a bump is just a bump, but other times it may be an important medical clue. A bump on a finger joint can sometimes be traced to an old trauma or a recent injury. In other instances, the bump may result when a sac of fluid, or cyst, develops. Less commonly, finger bumps may be signs of more widespread diseases that involve different organ systems.
One very common and relatively innocent bump that occurs near the finger joint is the callus that can develop from holding a writing implement. Those who have a particularly firm grip during writing are especially susceptible. The bump typically occurs on the middle finger, near the most distal joint of the fingertip.
Cysts are fluid-filled sacks. A tendon cyst is an abnormal sac of fluid that results from an injury to the tendon or sheath around the tendon. The cyst is usually less than a 1 cm in diameter and rarely interferes with joint function, and the knuckle joint where the finger joins the hand usually has full mobility. Ganglion cysts are more common in the wrist area, but they can occur over the fingertip and thumb joints, in which case they are called mucous cysts.
Osteoarthritis, sometimes called the “wear and tear” or "old age" variety of arthritis, frequently involves the small joints of the hand. Often there is painless bony enlargement of the small joints. Such bumps at the joints of the fingertips are called Heberden’s nodes, while those that occur in the finger joints that are closer to the hand are called Bouchard’s nodes. Bone spurs, or osteophytes, may be related to the arthritis and can also result in finger bumps.
Gout and Rheumatoid Arthritis
Rheumatoid arthritis and gout are two different forms of arthritis that can affect the joints of the fingers to create swelling and pain. So called gouty tophi are bumps from the disease gout, whereby uric acid crystals are deposited in the joints, causing painful attacks, often at night time. Although they may be confused for gouty tophi, rheumatoid nodules are firm lumps under the skin that are less likely to be painful. Rheumatoid nodules are indicative of rheumatoid arthritis, however not all individuals with rheumatoid arthritis have these nodules.
Other Causes and Warnings
In rare instances, a bump on he hand can be the result of a serious illness such as a malignancy. A tumor can begin as a bump or a cyst. Other causes of bumps may not be cancerous but, left untreated, could lead to reduced range of motion in the fingers. For these reasons, it is important to seek a physician’s opinion concerning bumps on the hand, particularly those that do not go away with time.