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Ganglion cyst

A large ganglion cyst on a person's wrist A ganglion is a fluid-filled swelling or cyst that is near a tendon or joint. Ganglion cysts look like smooth soft lumps under the skin. They are formed when some of the jelly-like fluid that is in the joint (called synovial fluid) leaks out. We don't know exactly what causes them. Sometimes they also go away by themselves, without any treatment.

Ganglion cysts are most common on the back of the wrist or the top of the foot, but they can happen anywhere. They are not harmful and are not cancer. But if they are large they can sometimes be painful, or can look unattractive.

Usually a doctor can diagnose a ganglion cyst simply by seeing it and you won't need any further tests.

The word "ganglion" can also mean a collection of nerve cells, but that's not the type of ganglion cyst we're talking about here.

Treating a ganglion cyst

You only need treatment for a ganglion if it's causing pain or problems when moving your joint, or if you think it looks very bad. Your doctor may recommend you wait to see if it changes. If it's painful, using a simple, soft, elasticated wrist support when you are doing anything that makes it hurt might help.

Your GP can try sucking out (aspirating) the fluid with a needle and syringe. The fluid is quite thick so this doesn't always work and the ganglion cyst often comes back. Adding a steroid injection at the same time can help reduce the chance of it coming back.

Your GP can also use a steroid injection to help reduce the size of the ganglion, which can help with the pain. If your GP is not experienced at giving steroid injections, they will be able to refer you to a GP who is. Musculoskeletal physicians can also inject steroids.

If your ganglion is causing significant pain or problems, then your GP can refer you to a plastic or orthopaedic surgeon, to investigate whether surgery is an option.

Surgery to cut out the ganglion has the best chance of curing it. However, this is not routinely offered for all ganglion cysts through the public system. There is also a 5% to 10% chance that the cyst will come back in the same position after surgery.

You could choose to pay to see a private plastic surgeon or private orthopaedic surgeon.

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Written by HealthInfo clinical advisers. Endorsed by clinical directors, Plastic Surgery and Orthopaedics departments, Canterbury DHB. Last reviewed April 2021.

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