A lump on the side of a finger can range from a simple fluid collection to a sign of age-related joint changes. Most lumps on the hand or finger are benign, but identifying their location and texture offers strong clues about their origin. This information provides an overview of common causes but should not be used to self-diagnose any medical condition.
Common Cysts and Fluid Collections
Fluid-filled sacs are among the most frequent causes of new lumps on the fingers. These collections are generally soft or spongy to the touch and often relate to the underlying joints or tendons.
Mucous cysts, also known as digital myxoid cysts, typically appear near the distal interphalangeal (DIP) joint, the joint closest to the fingertip. They present as translucent, slightly firm bumps on the back or side of the finger. These cysts are commonly associated with osteoarthritis, forming when bone spurs weaken the joint capsule. This allows synovial fluid to leak out and accumulate beneath the skin. Chronic pressure from the cyst can cause a distinct groove or indentation to form in the fingernail plate.
Another common fluid collection is the ganglion cyst, which originates from a tendon sheath or joint capsule. Ganglion cysts contain a thick, clear, gel-like fluid and are often found at the base of the finger near the palm. While they can sometimes feel soft and movable, those at the base of the finger may feel very firm, almost like a small, hard pea under the skin. These cysts can fluctuate in size, sometimes enlarging with increased hand activity before shrinking with rest.
Bony Growths and Joint Nodules
Lumps that feel hard, fixed, and immovable are often related to the underlying skeletal structure or degenerative joint disease. These growths are firm because they are composed of bone tissue, differentiating them from softer, fluid-filled cysts.
Heberden’s nodes are common bony enlargements that occur on the sides of the DIP joint, the joint nearest the fingertip. These hard, fixed lumps are a classic manifestation of osteoarthritis, developing as the protective cartilage breaks down. The body responds to this cartilage loss by forming new bone, or osteophytes, which creates the visible nodule.
A similar type of bony growth, called Bouchard’s nodes, affects the middle joint of the finger, known as the proximal interphalangeal (PIP) joint. Both Heberden’s and Bouchard’s nodes are slowly developing enlargements that may cause the finger joint to appear crooked or swollen. While they may be painful during their formation, they often become painless once the growth process stabilizes.
Skin and Surface Lesions
Some lumps originate directly from the skin or the soft tissues just beneath the surface, presenting with distinct colors and textures. A common surface growth is the wart, caused by the human papillomavirus (HPV), which presents as a rough, grainy lesion on the skin. Warts are typically benign but can be contagious and may feel tender if located on a pressure point.
Lumps stemming from infection are often accompanied by signs of acute inflammation, presenting as warm, red, and painful swellings. A felon, for example, is a deep abscess that forms in the fingertip pulp, causing severe throbbing pain. A paronychia is a painful bacterial infection that affects the skin around the nail fold, often presenting with redness and pus accumulation near the cuticle.
Other soft-tissue lumps include lipomas and fibromas, which are noncancerous masses that grow slowly. A lipoma is a collection of fatty tissue that feels soft, rubbery, and easily movable when pressed. Fibromas are tumors of fibrous connective tissue; while generally painless, their slow growth and firm texture can sometimes cause concern.
Warning Signs and When to See a Doctor
While most finger lumps are harmless, certain signs should prompt a medical evaluation to rule out more complex issues. Any lump that begins to grow rapidly over a period of weeks or is accompanied by severe pain requires prompt attention. Redness, warmth, or pus draining from the lump indicate a potential infection that may require immediate treatment with antibiotics or drainage.
A lump that is causing numbness, tingling, or weakness in the finger suggests possible nerve compression and needs assessment by a physician. A healthcare provider can typically diagnose the lump with a physical examination. They often use imaging tools like X-rays or ultrasound to determine its internal structure and connection to the bone or joint.