A ganglion cyst is a tumor or swelling 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). 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 in women, and 70% occur in people between the ages of 20-40. Rarely, ganglion cysts can occur in children younger than 10 years.
- Ganglion cysts most commonly occur on the back of the hand at the wrist joint but they 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
Ganglion Cyst Causes
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 that then join into a larger, more obvious mass. The most likely theory involves a flaw in the joint capsule or tendon sheath that allows the joint tissue to bulge out.
Ganglion Cyst Symptoms
- The ganglion cyst usually appears as a bump (mass) that changes size.
- It is usually soft, anywhere from 1-3 cm in diameter, 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 up to 35% are without symptoms except for appearance.
- If pain is present, it is usually chronic and made worse by joint motion.
- When the cyst is connected to a tendon, you may feel a sense of weakness in the affected finger.