A fluid-filled cyst that most commonly develops on the wrist or back of the hand and sometimes the foot

  • Age, gender, genetics, and lifestyle are not significant factors

A ganglion is a cyst that develops under the skin near a joint and is filled with a jelly-like fluid. The ganglion is usually an outgrowth from the capsule surrounding a joint or from the sheath of a tendon, the fibrous cord that attaches muscle to bone. The fluid inside the ganglion is derived from the synovial fluid that lubricates tendons and joints.

Ganglia are extremely common and are usually painless. They most commonly occur on the wrist or the back of the hand but occasionally they develop on the foot. They vary in size from that of a small pea to that of a plum.

A ganglion may be felt as a lump under the skin and may be present for several years without causing a problem. However, some ganglia become very uncomfortable or even painful. A ganglion may disappear spontaneously, or it can be removed surgically under local anaesthesia. Ganglia sometimes recur.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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