A ganglion cyst is a round, fluid-filled lump of tissue that usually appears along tendons or joints. It typically occurs on the wrist or hand, but it can also appear on the ankle or foot.

Ganglion cysts range in size. They can be as small as a pea or as large as a golf ball. They can also be soft or firm. Some cysts are visible underneath the skin, but others are so small that you can’t see them.

These types of cysts are common and usually harmless. They aren’t cancerous. Most go away without treatment.

It’s possible to have a ganglion cyst and not even know it. If symptoms do occur, the most common sign of a ganglion cyst is a visible lump or mass on your wrist, hand, ankle, or foot.

If the cyst is on your foot or ankle, you may feel discomfort or pain, especially when walking or wearing shoes. If the cyst is near a nerve, it can sometimes cause:

  • a loss of mobility
  • numbness
  • pain
  • a tingling sensation

Some ganglion cysts can become bigger or smaller over time.

When visible, a ganglion cyst looks like a round or misshapen lump or bump just below the skin’s surface. It often appears on your wrist, finger, or ankle, or foot. Because it’s filled with liquid, it can sometimes appear to be translucent.

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Ganglion cyst on the wrist.
Stanislav Sablin/Getty Images

There’s no known cause for ganglion cysts. These types of cysts occur as a result of some type of trauma or irritation.

Ganglion cysts occur when fluid accumulates in a joint or around the tendons in your:

  • hand
  • wrist
  • ankle
  • foot

This accumulation may happen due to injury, trauma, or overuse. There’s also evidence that these cysts may be related to arthritis.

Anyone can develop a ganglion cyst. They’re more likely to occur in people ages 15 to 40. They’re more common in women compared to men, according to the American Academy of of Orthopaedic Surgeons.

These types of cysts also tend to develop more frequently in people who repeatedly stress their wrists, such as gymnasts.

Other factors that may increase your risk of developing a ganglion cyst include:

  • injury to the wrist or finger
  • inflammation in a joint or tendon
  • repetitive wrist or finger activities
  • chronic conditions like arthritis

Your doctor will first examine the lump. They’ll ask you about your medical history and how long you’ve had the lump. They’ll also ask you about your symptoms.

They may order imaging tests, such as an X-ray, ultrasound, or MRI, especially if they can’t see the lump.

Transillumination, or the process of shining light through an area of the body to check for abnormalities, is also used to help differentiate between a solid tumor and one that’s filled with liquid, like a ganglion cyst.

The doctor may also take a sample of the fluid in the cyst for testing.

Ganglion cysts often go away without treatment. If the cyst doesn’t cause pain or discomfort, treatment isn’t necessary. Your doctor may advise you to do the following:

  • Avoid repetitive hand and wrist movements.
  • Wear a wrist brace because immobilization might cause the cyst to shrink.
  • Wear shoes that don’t touch the cyst if it’s on your foot or ankle.

If the ganglion cyst causes pain or limits your mobility, your doctor may aspirate it. During this procedure, they’ll drain fluid from the cyst with a syringe.

Surgical removal is an option if other treatments haven’t worked. However, the cyst may return even if your doctor has surgically removed it.

There’s no known way to prevent a ganglion cyst. If you’re prone to developing these types of cysts, even with treatment, they can reoccur.

If a ganglion cyst returns and becomes bothersome, talk with a doctor or medical professional about the next steps to treat it or remove it.

Ganglion cysts are noncancerous lumps that are, for the most part, harmless and won’t need treatment.

Talk with a doctor if they cause pain or you’re unhappy with the appearance of the cyst. Treatment options are available.