These are common fluid filled sacs presenting as swelling around joints or tendons, typically on the back of the wrist, near the ends of fingers (mucous cysts or pearl ganglia) or at the front of the wrist. The cause is usually unknown and several theories are postulated including wear and tear of the underlying joint or tendon resulting in synovial or joint fluid leaking out presenting as a swelling.
Ganglia may or may not be painful. They can become bigger or smaller and can disappear with time.
If the ganglion is not painful then reassurance and confirmation of the diagnosis is all that is required. If symptomatic then the first line treatment is aspiration which has a 50% success rate. Surgery is offered if the ganglion is persistently painful but there is a recurrence rate.