Ganglion Cyst: What Causes a Lump on the Wrist and How Is It Treated?

What is a ganglion cyst?

A ganglion cyst is a small sac that grows out of a joint or tendon sheath, like a balloon on a stalk, and is filled with thick, jelly-like fluid similar to joint fluid. It is the most common cause of a lump in the hand and wrist and is benign, meaning it is not cancer ^[1]⁠^[3].

The most common sites are the back of the wrist, the palm side of the wrist near the base of the thumb, the palm side of the base of a finger, and the back of the end joint of a finger ^[1]⁠^[3].

What are the symptoms?

Cysts range from smaller than a pea to a few centimetres across and may grow or shrink over time ^[1]⁠^[2]:

• A smooth, soft or firm lump under the skin
• Often painless; sometimes an ache after using the joint
• Tingling, numbness or weakness if the cyst presses on a nerve
• Pain even from small cysts that cannot be seen under the skin
• Concern about appearance

What causes it, and who is at risk?

The exact cause of ganglion cysts is not known. They sometimes appear after an injury causes fluid to leak from a joint ^[1]⁠^[2].

They are more common in women and in people aged 15 to 40. They are also more frequent in athletes whose wrists are repeatedly stressed, such as gymnasts, and in people with arthritis. Cysts on the back of the end joint of a finger usually appear in middle-aged and older people together with arthritis of that joint ^[1]⁠^[2].

How is it diagnosed?

Diagnosis is usually made by examination. The doctor checks the position, consistency and tenderness of the lump and may shine a light through it to see whether it is filled with fluid ^[1].

X-rays may be taken to rule out bone or joint problems. Ultrasound or MRI can show small hidden cysts and confirm that a lump is really a cyst ^[1]. Any lump that is hard, fixed or growing quickly should always be checked ^[2].

Non-surgical treatment: watching and aspiration

Watching a painless cyst is a safe approach. Many cysts shrink or disappear on their own, which can take from several months to a year ^[1]⁠^[2]⁠^[3]. A wrist support and short-term painkillers can ease symptoms ^[1]⁠^[2].

Trying to burst the cyst at home or hitting it with a heavy object is not recommended, as this can cause infection and damage to the tissues ^[2].

Draining the cyst with a needle (aspiration) makes it smaller, but because the root of the cyst stays in place it often comes back ^[1]⁠^[3]. A meta-analysis found that aspiration did not clearly reduce recurrence compared with simply watching the cyst ^[4].

When is ganglion cyst surgery needed?

Surgery may be considered if the cyst is painful, causes numbness or weakness by pressing on a nerve, interferes with daily activities, or keeps returning despite other treatment ^[1]⁠^[3].

During the operation the cyst is removed together with its stalk, which connects it to the joint or tendon sheath. It is usually a day-case procedure ^[1]. A meta-analysis showed that surgical removal clearly lowered the risk of recurrence compared with needle drainage, although complications were more frequent with surgery ^[4].

A cyst can still come back after surgery, and this risk depends on where it is. Recurrence is more common for cysts on the palm side of the wrist, an area close to an important artery, so the decision is tailored to the site of the cyst ^[3].

Recovery

After surgery there may be tenderness, swelling and discomfort for a while. Most people return to their usual activities within two to six weeks ^[1].

Possible problems include ongoing pain and irritation of small nearby nerves, and for finger cysts, infection and joint stiffness ^[3].

When should you see a doctor promptly?

Seek assessment without delay if ^[1]⁠^[2]:

• The lump becomes very painful, hot or red
• The lump is hard, does not move, or grows quickly
• You have numbness, tingling or weakness in the hand or fingers