These are common features of ganglion cysts:

• Location. Ganglion cysts most often develop along the tendons or joints of wrists or hands. The next most common locations are the ankles and feet. These cysts grow near other joints too.
• Shape and size. Ganglion cysts are round or oval. Some are too small to feel. The size of a cyst can change, often getting larger over time with joint movement.
• Pain. Ganglion cysts usually are painless. But if a cyst presses on a nerve or other structures, it can cause pain, tingling, numbness or muscle weakness.

When to see a doctor

See a health care provider if you notice a lump or pain in your wrist, hand, ankle or foot. You can get a diagnosis and find out whether you need treatment.

No one knows what causes a ganglion cyst. It grows out of a joint or the lining of a tendon and looks like a tiny water balloon on a stalk. Inside the cyst is a thick fluid like the fluid found in joints or around tendons.

Factors that may increase the risk of ganglion cysts include:

• Sex and age. Ganglion cysts can develop in anyone, but they most often occur in women between the ages of 20 and 40.
• Osteoarthritis. People who have wear-and-tear arthritis in the finger joints closest to the fingernails are at higher risk of developing ganglion cysts near those joints.
• Joint or tendon injury. Joints or tendons that have been injured are more likely to develop ganglion cysts.

During the physical exam, a health care provider might press on the cyst to see if it hurts. Shining a light through the cyst might show if it's solid or filled with fluid.

Imaging tests — such as an X-ray, ultrasound or MRI — can help confirm the diagnosis as well as rule out other conditions, such as arthritis or a tumor.

Fluid drawn from the cyst with a needle might confirm the diagnosis. Fluid from a ganglion cyst is thick and clear.

Ganglion cysts are often painless and need no treatment. Your health care provider might recommend watching the cyst for any changes. If the cyst causes pain or gets in the way of joint movement, you may need to:

• Keep the joint from moving. Activity can cause a ganglion cyst to grow. So wearing a brace or splint to keep the joint still for a time might help. As the cyst shrinks, it may release the pressure on nerves, relieving pain. But long-term use of a brace or splint can weaken nearby muscles.
• Drain the cyst. Draining the fluid from the cyst with a needle might help. But the cyst can come back.
• Surgery. This may be a choice if other approaches don't work. Surgery involves removing the cyst and the stalk that attaches it to the joint or tendon. Rarely, surgery can injure the nearby nerves, blood vessels or tendons. And the cyst can come back, even after surgery.

What not to do

An old home fix for a ganglion cyst involves hitting the cyst with a heavy object. This isn't a good thing to do. The force of the blow can damage hands or feet. Also, sticking a needle in the cyst to try to "pop" it can lead to infection.

You might start by seeing your primary care provider. You might then get a referral to a hand or foot surgeon.

What you can do

Before your appointment, you might want to write down answers to the following questions:

• How long have you had the lump? Does it come and go?
• Have you ever injured the joint nearest the lump?
• Do you have arthritis?
• What medicines and supplements do you take regularly?

What to expect from your doctor

Your health care provider is likely to ask you questions, such as:

• Do you have pain or tenderness?
• Does the bump keep you from using your joint?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?