Noticing a small bump suddenly appear on your wrist can be unsettling.

You might wonder if it's an injury, a swollen joint, a tumor, or something more serious. Sometimes the lump may become more noticeable when you move your wrist, while at other times it may seem to disappear almost completely.

One common explanation is a ganglion cyst.

Ganglion cysts are fluid-filled lumps that commonly develop around joints or tendons, particularly in the wrist and hand. They are non-cancerous and, in many cases, harmless.

However, that doesn't mean every lump on the wrist is automatically a ganglion cyst.

Understanding what these cysts look and feel like, why they develop, when they may need treatment, and which warning signs shouldn't be ignored can help you know what to do next.

What Is a Ganglion Cyst?

A ganglion cyst is a small sac filled with a thick, jelly-like fluid.

It usually develops near a joint or tendon sheath, where connective tissue surrounds and supports movement.

The wrist is one of the most common places for these cysts to appear.

They can develop on:

• The back of the wrist

• The palm side of the wrist

• The base of a finger

• The back of a finger joint

• Around certain tendons

A ganglion cyst may feel:

• Smooth

• Firm or rubbery

• Soft in some cases

• Round or oval

• Slightly movable

• Larger or smaller depending on the position of the joint

Some are barely noticeable.

Others can become large enough to be obvious.

Why Does a Ganglion Cyst Form?

The exact reason a particular person develops a ganglion cyst isn't always clear.

One theory is that the cyst develops when fluid associated with a joint or tendon pushes through a weakened area of surrounding tissue.

The resulting sac can gradually fill with thick, clear or jelly-like fluid.

Some ganglion cysts may be associated with:

• Joint irritation

• Repetitive wrist movement

• Previous injury

• Repeated stress on a joint

• Degenerative changes around a joint

But sometimes a person develops one without any obvious trigger.

You don't necessarily need to remember an injury for a ganglion cyst to appear.

Is a Ganglion Cyst Cancer?

Ganglion cysts are non-cancerous.

That is one reason they are generally considered benign.

However, the fact that ganglion cysts are harmless doesn't mean that every lump on the wrist should be assumed to be one.

Other conditions can also cause lumps or swelling.

For example, a wrist lump could potentially be related to:

• A lipoma

• Arthritis

• A tendon problem

• A benign growth

• An inflammatory condition

• A previous injury

• An infection

• Less commonly, another type of mass

This is why a new or unexplained lump should be assessed if you're uncertain about what it is.

What Does a Ganglion Cyst Feel Like?

The texture can vary.

Some ganglion cysts feel relatively firm, while others have a softer or more compressible texture.