What is a ganglion?
A ganglion is a sac-like swelling or cyst formed from the tissue that lines a joint or tendon. The tissue, called synovium, normally functions to produce lubricating fluid for these areas. A ganglion is a cyst formed by the synovium that is filled with a thick jelly-like fluid. While ganglia can follow local trauma to the tendon or joint, they usually form for unknown reasons. Occasionally, ganglia are early signs of arthritis that will become more obvious in the future.
Where do ganglia form and what symptoms do they cause?
Ganglia can form around any joint, but they are most frequently found in the wrist and ankles. They are usually painless and often barely visible as localized swellings. They typically do not appear to be inflamed. The largest ganglions form behind the back of the knee, causing a sense of fullness or tightness. A ganglion here is referred to as a Baker cyst, after the doctor who originally described the condition.
How are ganglia treated?
A ganglion can spontaneously rupture and go away. Other treatment options include removal of the ganglion fluid with a needle and syringe (aspiration) with or without an injection of cortisone medication. Occasionally, the entire ganglion is resected with surgery. People with a persisting or recurring ganglion should be evaluated for signs of systemic forms of arthritis, such as rheumatoid arthritis.
For further information, please visit the Arthritis Center.