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Ganglion cysts are noncancerous lumps that most commonly develop along the tendons or joints of your wrists or hands. They also may occur in the ankles and feet. Ganglion cysts are typically round or oval and are filled with a jellylike fluid.

Small ganglion cysts can be pea-sized, while larger ones can be around an inch (2.5 centimetres) in diameter. Ganglion cysts can be painful if they press on a nearby nerve. Their location can sometimes interfere with joint movement.

Symptoms

The lumps associated with ganglion cysts can be characterized by:

• Location
• Shape and size
• Pain

When to see a doctor

See your doctor if you experience a noticeable lump or pain in your wrist, hand, ankle or foot. He or she can make a diagnosis and determine whether you need treatment.

Causes

No one knows exactly what causes a ganglion cyst to develop. It grows out of a joint or the lining of a tendon, looking like a tiny water balloon on a stalk, and seems to occur when the tissue that surrounds a joint or a tendon bulges out of place. Inside the cyst is a thick lubricating fluid similar to that found in joints or around tendons.

Risk factors

Factors that may increase your risk of ganglion cysts include:

• Your sex and age
• Osteoarthritis
• Joint or tendon injury

Diagnosis

During the physical exam, your doctor may apply pressure to the cyst to test for tenderness or discomfort. He or she may try to shine a light through the cyst to determine if it's a solid mass or filled with fluid.

Your doctor might also recommend imaging tests such as X-rays, ultrasound or magnetic resonance imaging (MRI) to rule out other conditions, such as arthritis or a tumor. MRIs and ultrasounds also can locate hidden (occult) cysts.

Treatment

Ganglion cysts are often painless, requiring no treatment. Your doctor may suggest a watch-and-wait approach. If the cyst is causing pain or interfering with joint movement, your doctor may recommend:

• Immobilization
• Aspiration
• Surgery