Mucous Cyst

Mucous (or mucoid) cysts are a type of ganglion or fluid-filled cyst that occur at the terminal joint of the fingers or thumb (the joint closest to your fingernail). The fluid within the cyst arises from the underlying joint, termed the distal interphalangeal joint (DIPJ) in the fingers or the interphalangeal joint (IPJ) of the thumb. Mucous cysts are harmless but they can cause pain (especially when large) and nail ridging. Sometimes they burst and express a clear fluid. Mucous cysts tend to fluctuate in size and most will disappear without any treatment within a few years.

Mucous cysts typically arise in those aged over 45 years and are often associated with early or moderate osteoarthritis of the underlying joint (DIPJ or IPJ). Although osteoarthritis typically produces pain, stiffness and reduced movement, it is not uncommon for mucous cysts to be pain-free unless large. Sometimes mucous cysts occur without any underlying arthritis. 

Read more about finger and DIPJ osteoarthritis.

There are other causes of finger pain and swelling and a thorough assessment will help to identify the cause.

Does your finger have a small fluid-filled lump near the fingernail?

  • Some of the potential symptoms of a mucous cyst are listed below.

    Typically present:

    • Cyst or lump over the terminal joint of the finger or thumb (often painless, especially when small).

    Sometimes present:

    • Nail ridging or furrowing (deformity).

    • Pain at the cyst (especially when large) or underlying joint.

    • Bursting of the cyst (clear gel-like fluid).

  • Most mucous cysts will not require any treatment as they are harmless and will generally disappear with time. 

    Mucous cysts should not be burst intentionally due to the risk of deep infection (of the underlying joint). If the cyst bursts naturally it is important to keep the wound clean, dry and covered with a dressing to avoid infection.

    • Non-surgical treatment options include simple painkillers and protecting the cyst from bursting.

    • Surgical treatment is reserved for persistently painful or discharging cysts. Mucous cysts can be excised with a cuff of overlying skin. Cyst excision is commonly combined with excision of any underlying bone spurs (osteophytes). Excision will sometimes require a large flap of skin to be rotated from the back of your finger to close the skin hole and cover the underlying joint. Mucous cysts can recur following surgery and any underlying osteoarthritis will not be changed by cyst excision.

    Matthew offers all the above treatments.

    Mucous cyst surgery is usually performed under local anaesthesia. Click here for an overview of the different types of anaesthesia and the general risks of hand surgery.

    The specific risks associated with mucous cyst surgery will be discussed if surgery is an option, but includes deep infection, stiffness and recurrence.

  • You can read more detailed information about mucous cysts on the Lothian Hand Unit website.

The information contained on this page is for guidance only and should not be considered a substitute for medical assessment and advice by a suitably trained doctor or clinician. External links have been provided for your information and convenience and we are not responsible for their content or accuracy.