Bumps appearing on finger joints are a frequent and often concerning physical symptom. These growths have a wide range of causes, from chronic joint changes to fluid-filled sacs or acute inflammatory deposits. Identifying the nature of the bump—whether hard and fixed, soft and movable, or suddenly inflamed—is the first step toward understanding the underlying condition. The physical characteristics of these bumps are tied directly to their origin.
Bumps Caused by Joint Degeneration
The most common cause of hard, fixed bumps on finger joints is osteoarthritis (OA), the long-term deterioration of cartilage. This degenerative process involves the gradual breakdown of protective cartilage, leading to bone-on-bone friction. The body attempts to repair this damage by stimulating new bone tissue growth, resulting in hard, bony enlargements called osteophytes or bone spurs.
These bony growths manifest in two specific locations. Bumps on the joint closest to the fingertip (distal interphalangeal or DIP joint) are called Heberden’s nodes, while enlargements on the middle joint (proximal interphalangeal or PIP joint) are called Bouchard’s nodes. These nodes are characteristically firm and fixed because they are extensions of the underlying bone structure.
Other chronic joint diseases produce different types of bumps. Rheumatoid arthritis (RA), an autoimmune inflammatory condition, causes firm lumps known as rheumatoid nodules. These masses of inflammatory tissue form under the skin, often over areas subjected to pressure like the knuckles. Rheumatoid nodules tend to be movable and rubbery, distinguishing them from the hard texture of OA-related nodes.
Psoriatic arthritis (PsA) presents dactylitis, a unique swelling that affects the entire digit rather than just the joint line. This causes the finger to swell uniformly, giving it the appearance of a “sausage digit” due to inflammation. These characteristics—hard bone, rubbery tissue, or diffuse swelling—serve as distinct markers for the type of arthritis present.
Soft Tissue Growths and Cysts
Bumps that feel soft, fluid-filled, or movable often originate from the soft tissues surrounding the joint, rather than the bone. One common soft tissue growth is the mucous cyst, which typically appears at the DIP joint, close to the nail bed. These cysts are sacs filled with a clear, thick, jelly-like fluid originating from the joint capsule itself.
Mucous cysts are often connected to underlying osteoarthritis changes; a bone spur may compromise the joint capsule, allowing synovial fluid to leak out. Their location can cause pressure on the nail matrix, potentially leading to a groove or deformity in the fingernail. While firm, they lack the hardness of a bone spur and may fluctuate in size.
Another type of soft bump is the ganglion cyst, the most common soft tissue mass in the hand and wrist, which can also appear on the fingers. These cysts grow out of a joint or tendon sheath and are filled with a viscous, jelly-like substance. Ganglion cysts are smooth and movable under the skin, sometimes appearing larger with activity and smaller with rest.
Soft tissue cysts are anomalies that may spontaneously disappear over time without intervention. Their texture and mobility differentiate them from the fixed bony enlargements associated with chronic joint degeneration.
Acute Conditions and Skin-Related Bumps
Some finger bumps have a rapid onset, linked to acute inflammatory events or superficial skin lesions. Gout is a form of inflammatory arthritis caused by the accumulation of monosodium urate crystals in the joint and surrounding tissues. An acute gout attack causes sudden, intense pain accompanied by swelling, redness, and warmth, often mimicking a severe infection.
Long-term, untreated gout can result in the formation of tophi, hardened deposits of uric acid crystals. These manifest as painless, chalky-white or yellowish nodules under the skin, often found on the fingers. The presence of these crystal aggregates distinguishes gout-related bumps from bone spurs or fluid-filled cysts.
Other bumps are purely superficial and do not involve the underlying joint structure. A common wart, caused by the human papillomavirus (HPV), presents as a small, grainy, rough growth on the skin. Warts may contain tiny black dots (clotted blood vessels) and can occur near a joint.
A callus is an area of thickened, hardened skin that forms in response to repeated friction or pressure. Calluses are smooth and uniform in texture, lacking the grainy surface or viral origin of a wart. These lesions are easily differentiated from joint-related growths because they only involve the outermost layers of tissue.
Determining When to Consult a Doctor
While many finger bumps are benign, medical evaluation is warranted when certain warning signs appear. Immediate consultation is necessary if a bump is accompanied by rapid swelling, intense pain, or significant warmth and redness, as these symptoms can indicate an acute inflammatory flare or a serious joint infection.
Seek medical advice if a bump causes a noticeable loss of joint mobility or interferes with daily tasks. Any soft tissue bump that begins to drain fluid (like a mucous cyst) requires evaluation to prevent infection from entering the joint. Diagnosis is necessary to differentiate between the various forms of arthritis and initiate appropriate management for chronic conditions.