A ganglion cyst is a tumor or swelling (benign, not cancerous) usually on top of a joint or the covering of a tendon (tissue that connects muscle to bone). It looks like a sac of liquid (cyst) located just under the skin. Inside the cyst is a thick, sticky, clear, colorless, jellylike material. Depending on the size, cysts may feel firm or spongy.
One large cyst or many smaller ones may develop. Multiple small cysts can give the appearance of more than one cyst, but a common stalk within the deeper tissue usually connects them. This type of cyst is not harmful and accounts for about half of all soft-tissue tumors of the hand.
Ganglion cysts, also known as Bible cysts, are more common (three times more) in women than in men, and a majority occur in people between 20-40 years of age. Rarely, ganglion cysts can occur in children younger than 10 years of age.
Ganglion cysts most commonly occur on the back of the hand, at the wrist joint, and can also develop on the palm side of the wrist. When found on the back of the wrist, they become more prominent when the wrist is flexed forward. Other sites, although less common, include these:
The base of the fingers on the palm, where they appear as small pea-sized bumps
The fingertip, just below the cuticle, where they are called mucous cysts
The outside of the knee and ankle
The top of the foot or toes
What Causes a Ganglion Cyst?
The cause of ganglion cysts is not known. One theory suggests that trauma causes the tissue of the joint to break down forming small cysts, which then join into a larger, more obvious mass. The most likely theory involves a flaw in the joint capsule or tendon covering (sheath) that allows the joint connective tissue to bulge out. Chronic damage may cause cells to produce mucin and fluid.
What Are Symptoms and Signs of a Ganglion Cyst?
The ganglion cyst usually appears as a bump (mass) that changes size.
It is usually soft, anywhere from 1-3 cm in diameter (about .4-1.2 inches) and doesn't move.
The swelling may appear over time or appear suddenly, may get smaller in size, and may even go away, only to come back at another time.
Most ganglion cysts cause some degree of pain, usually following acute or repetitive trauma, but many are without symptoms, except for their appearance.
The pain is usually nonstop, aching, and made worse by joint motion.
When the cyst is connected to a tendon, one may feel a sense of weakness in the affected finger.
When Should Someone Seek Medical Care for a Ganglion Cyst?
A ganglion cyst can benefit from medical evaluation whether or not there are symptoms. A doctor can be sure that you have a ganglion cyst, keep you from worrying, and help decide on the best treatment plan for you.
A ganglion cyst does not need to have emergency treatment unless one has significant trauma. A routine check by either a primary doctor or a specialist in bones and joints (an orthopedist) usually can result in both diagnosis and treatment of many ganglion cysts.