Understanding Mucous Cysts

What are the causes of a Mucous Cyst?

Mucous cysts often form due to osteoarthritis. Arthritis can lead to the development of small bone spurs, known as osteophytes, around a joint. These spurs can penetrate the joint capsule, allowing joint fluid to seep into surrounding tissues and form a cyst. In rare cases, mucous cysts may develop without underlying arthritis, though the cause in these instances is not well understood.

What are the symptoms of a Mucous Cyst?

A mucous cyst typically appears as a small, painless swelling on the back of a finger near the DIP joint. While any finger can be affected, the cyst may vary in size and sometimes causes a groove in the nail due to its pressure on the nail bed. Most people do not experience significant discomfort or functional issues, though a cyst can occasionally become tense and tender if fluid builds up. If bumped, the cyst may sometimes release a clear, jelly-like fluid.

How is a Mucous Cyst diagnosed?

The diagnosis of a mucous cyst is usually made based on its distinct appearance near the end of a finger. Additional tests are rarely necessary.

What is the natural history of Mucous Cysts?

Mucous cysts tend to fluctuate in size on their own, with symptoms sometimes worsening as the cyst enlarges and easing as it reduces. Over time, most cysts will shrink and disappear, though some can persist. Occasionally, the cyst may repeatedly discharge fluid, which can be problematic.

What are the risks of a Mucous Cyst?

Most mucous cysts are harmless. However, if a cyst consistently discharges, there is a slight risk of infection, which could potentially spread to the nearby joint and cause damage.

What treatment is recommended for a Mucous Cyst?

Since mucous cysts are generally benign and often resolve without treatment, doctors typically advise leaving them alone. While some individuals with painful cysts may consider removal, most cysts may disappear by themselves.

When deciding whether to treat a mucous cyst, it’s important to weigh the risks of intervention against the low risk of doing nothing. Treatment options include:

• Aspiration (Needle Drainage): If a mucous cyst is large and uncomfortable, it can be drained with a needle to remove the fluid. While aspiration may relieve symptoms temporarily, many cysts refill with fluid. The main risk with aspiration is introducing infection to the joint.
• Surgical Removal: While surgery to remove the cyst may seem straightforward, it can be complex, as it involves not only removing the cyst but also addressing the bone spur causing it. During surgery, the skin over the cyst is lifted, the cyst is removed, and any bone spur is treated. However, surgery does not address the underlying arthritis, meaning the cyst may return.

Risks of Surgery: Surgery carries certain risks, including infection, joint stiffness, issues with skin healing, and potential recurrence of the cyst. In some cases, these complications can leave patients worse off than before the surgery.