What is a Ganglion?

A ganglion is a fluid filled lump that usually occurs under the skin. Ganglia feel quite firm, can fluctuate in size and tend to occur around joints, most commonly on the back of the hand and wrist. On the finger ganglia are sometimes referred to as “mucous cysts”. They are benign, non-cancerous lumps.


What causes a ganglion?

Ganglia originate from the joint they overlie. They are like balloons, filled with joint fluid. The stalk of the balloon communicates with the underlying joint and acts like a one-way valve, filling the cyst with thick joint fluid.


It is not known what causes ganglia. One theory is they are often preceded by a minor injury. Another theory is that ganglia are caused by arthritic changes to the underlying joint, resulting in increased production of joint fluid which is looking for a means of escape.


How is a ganglion diagnosed?

Your doctor can often diagnose a ganglion by its appearance and location. Sometimes an ultrasound scan can be useful to support the diagnosis. Removing the cyst and examining it under a microscope is the definitive method of diagnosis (and treatment).


What treatment is required for a ganglion?

The vast majority of ganglia do not require treatment. If the lump is not bothersome, no treatment is required.


The old fashioned technique of rupturing the cyst by striking it with a heavy book such as the Bible is not recommended!


Orthopaedic surgeon Dr Pritpal Bansi warns never to try draining the cyst yourself with a needle. As ganglia communicate with the underlying joint, you risk introducing infection resulting in ‘septic arthritis’ and permanent damage to your joint. However, aspirating and injecting the cyst with steroid under ultrasound guidance in a medical setting can be done for temporary relief.


Surgery is the definitive treatment, ensuring that the entire ganglion including the stalk emanating from the underlying joint is also removed.


See your GP for further advice or referral to an orthopaedic surgeon.


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