Synovial Cysts
What is a synovial cyst ?
A synovial cyst is a benign swelling filled with synovial fluid, the natural lubricating fluid found in joints and tendon sheaths.
It most commonly appears on the back of the wrist but can also develop on the palmar aspect or at the base of the fingers.
It arises from a herniation of a joint capsule or tendon sheath, forming a pocket that gradually fills with fluid. Synovial cysts are always benign. They may be asymptomatic and discovered incidentally, or may cause cosmetic concern, pain on wrist movement or pressure on nearby structures.
Does it need treatment ?
When a synovial cyst causes no pain or functional limitation, observation is a reasonable option, some cysts resolve spontaneously over time.
When the cyst is symptomatic, ultrasound-guided aspiration is the treatment of choice.
Surgical excision is not recommended as a first-line treatment, as recurrence rates following surgery are comparable to those after aspiration, for a significantly more invasive procedure.
How is the aspiration performed ?
Aspiration is performed by a radiologist in the outpatient clinic under ultrasound guidance.
Real-time imaging allows the needle to be directed precisely into the cyst, even small or deep cysts can be safely and accurately targeted.
The fluid is aspirated and a corticosteroid injection may be added to reduce local inflammation and limit the risk of recurrence. The procedure takes only a few minutes, requires no general anaesthesia and no hospitalisation. The patient leaves immediately afterwards.
What is the recovery ?
A simple dressing is applied after the procedure. Normal hand use can be resumed the following day. Mild local discomfort may persist for a few days.
If the cyst recurs, aspiration can be repeated. Some cysts require more than one aspiration before resolving definitively.