Mucous cyst
Hand Conditions
Wrist Conditions
Elbow Conditions
What is it?
A mucous cyst is a lump on the finger caused by a fluid filled sac. It appears near the nail bed and can occur in any finger. It can occur in a single finger or in multiple fingers.
It generally forms due to degeneration and arthritis (wear and tear) of the underlying joint, where the joint fluid leaks under the skin and forms the cyst.
What are the symptoms?
Most mucous cysts are not painful. However, they can be tender to touch and cause pain when ‘caught’ against an object.
When they become larger, they can also press on the nail bed and cause an unsightly deformity of the nail itself.
Occasionally, the cyst can burst, causing the joint fluid to leak out. Joint fluid can also leak out through a punctum on top of the cyst. This can lead to infection and sepsis of the underlying joint, and it is a medical emergency.
If your cyst is discharging, we would advise you to seek medical attention as it can lead to a septic infection of the joint and finger.
what is the treatment?
When mucous cysts are small, pain free and not discharging fluid, they can be observed safely without any treatment.
For larger cysts that are painful, discharging fluid or causing a nail deformity, a small operation is required to remove the cyst and its sac. This will prevent worsening of your symptoms and prevent infection of the underlying joint. It can also restore the shape of the nail in many cases. A simple aspiration with a syringe is unlikely to work as the sac isn’t removed and the fluid re-accumulates very quickly.
Surgery to remove mucous cysts is performed under local anaesthesia where only the finger is ‘numbed’. This is the safest form of operation. Through a small cut, the cyst is removed completely, including the stalk that arise from the underlying joint. Arthritic bone fragments, called ‘osteophytes’, is also removed to reduce the chance of the cyst coming back. The scar tends to heal extremely well following this operation, and will be barely visible after in a few months.
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