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Ganglion cysts are small, benign, fluid-filled sacs. They usually form on or near a joint or the covering of a tendon.

These cysts usually develop on the wrist, but they can appear on the hand, ankle, foot, or knee. They look like small lumps under the skin.

Ganglion cysts are not cancerous, and they are usually harmless. If they cause pain, difficulty moving the joint, or if the person feels that they are unsightly, a doctor may remove them.

Ganglion cysts mostly affect people aged 15–40 years, and they develop more often in females than in males. They are quite common, but doctors do not know very much about them. The authors of one study describe them as "enigmatic."

Ganglion cysts on the wrist. Image credit: Kulzerwi, 2006Share on Pinterest
Ganglion cysts are benign lumps that often go away on their own.
Image credit: Kulzerwi, 2006

Ganglion cysts often appear on the back of the wrist. They are round or oval-shaped lumps that contain fluid.

This type of cyst can range from the size of a pea to that of a golf ball. Beneath the skin, the cyst resembles a water balloon on a stalk.

Ganglion cysts do not pose a significant medical threat. If one pushes on a nerve, however, it can cause pain.

Also, depending on their size and location, these cysts can make some movements difficult.

A ganglion cyst always forms near a joint, and a doctor can usually recognize one by examining it visually.

They may be soft or hard, and they should be able to move freely under the skin.

Location: These cysts usually occur on the top or back of the wrist. Or, they may appear on the palm side of the wrist, on the palm at the base of a finger, or on top of a finger's end joint. They can also form on top of a foot, on an ankle, or on a knee.

Pain: Ganglion cysts may or may not be painful, depending on whether they press on a nerve.

Size: This can range from the size of a pea to that of a golf ball.

The area around the cyst may feel numb. If a cyst forms on the hand or wrist, the person may lose grip strength.

Doctors do not know what causes ganglion cysts. They may form when synovial fluid leaks from a joint.

A ganglion cyst tends to be attached to an underlying joint capsule or tendon sheath. They usually develop where a joint or tendon naturally bulges out of place.

Risk factors

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Ganglion cysts are most common in females aged between 15 and 40 years.

Risk factors seem to include:

Age and sex: Ganglion cysts can affect anyone at any time, but they most commonly occur in females aged 15–40 years.

Overuse: People who use certain joints vigorously may be more likely to develop ganglion cysts. Female gymnasts, for instance, may be particularly prone to developing these cysts.

Joint or tendon injury: At least 10% of ganglion cysts appear in an area that has sustained an injury.

Trauma: They may form following a single incident or reoccurring small injuries.

Formation

Experts do not know exactly how ganglion cysts form.

However, it appears that:

  • Joint stress may play a role, as the cysts often develop in sites of overuse or trauma.
  • They may develop following a leak of synovial fluid from a joint into the surrounding area.

How or why this happens is not entirely clear.

A ganglion cyst usually does not need treatment, as long as it causes no discomfort or pain. Up to half may disappear without intervention, but some take several years to resolve completely.

A doctor will recommend some form of treatment if the cyst is pressing on a nerve and causing pain.

If a cyst causes discomfort, the following can help:

Adapting footwear: If the cyst is on a foot or ankle, shoes should not rub or irritate it. It may help to wear soft or open shoes, insert padding, or lace the shoes in a different way.

Immobilization: Moving the affected area may increase the cyst's size. Wearing a splint or brace can help limit movement, and this may cause the cyst to shrink.

Pain relief: If the cyst is painful, over-the-counter pain medication, such as ibuprofen, can help.

Ibuprofen is available for purchase online.

Should I hit it with a blunt object?

A traditional remedy involves hitting a ganglion cyst with a heavy object, such as a book.

However, there is limited evidence that this method is safe or effective. Doctors do not advise people to do this, as the blow could damage surrounding structures in the body.

Dr. Owen Kramer told Medical News Today:

"It would be a very bad idea to hit any kind of protrusion or nodule, such as a ganglion cyst, in the hopes that it would clear. This could lead to a severe injury."

Individuals also should not try to "pop" their cysts, as this can lead to infection, and it is unlikely to resolve the issue.

If a person experiences significant discomfort, they should speak to their doctor about treatment.

In up to 50% of cases, ganglion cysts disappear without treatment. If the cyst is large, painful, or it causes problems, however, a doctor may recommend removing it with one of the following techniques:

Aspiration: This involves removing the fluid from the cyst. However, because the underlying structure remains, the cyst may form again. Some people need to undergo the procedure several times.

Surgery: A surgeon can make a small incision and remove the cyst and its stalk. Keyhole, or arthroscopic, surgery is also an option.

A small study published in 2006 found that around 30% of cysts came back after this surgery.

However, researchers writing in 2014 noted that arthroscopic surgery may be the way forward in resolving ganglion cysts. Open surgery, they noted, can leave an "unsightly scar."

Recovery

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Over-the-counter pain relief may help with recovery after surgery.

After surgery, the person should keep the area covered and protect it from being bumped accidentally.

Other tips include:

  • following the doctor's aftercare recommendations
  • wearing a splint for a few days, if the cyst was on the hand or wrist
  • using over-the-counter pain relief, if necessary
  • keeping the extremity raised to reduce the risk of swelling

If discomfort persists, see the doctor.