Cysts & Swellings in the Feet

David Tollafield
Apr 27
3 min read

Swellings in feet may be due to a cyst

Keywords: Ganglion, Bursa & Mucoid cyst

The foot can develop different swellings. The most obvious place to look is the ankle—fluid pools around the bottom of the leg because of gravity. As we age, fluid is more likely to gather, especially if the heart is less efficient or kidney problems arise.

In addition to this fluid, called oedema, we find another type of localised swelling. If pressed, the skin does not dent as in oedema.

Ganglionic Cyst & Swelling

A ganglion is essentially a cyst—a fluid-filled sac that forms a thin gossamer lining containing a clear, fluid-like gel. The formation arises from joint and tendon linings.

Some of the tendons have a secretory lining and can tear. These tears are so small that you cannot see them on ultrasound scans unless the fluid and lining are large, forming the catch-all term – cyst. Just because you may have cysts elsewhere in the body does not imply any relationship with the ganglionic cyst, sometimes known as a synovial cyst.

Other Ganglia in Feet?

ganglion midfoot joints. — **Midfoot and swelling on top of the foot**

In front of or on the side of the ankles, around the back of the heel, on the top of the feet, and on the side of the feet. Over the big toe, a ganglionic cyst becomes part of the all-encompassing bunion.

While harmless, in many cases, all swellings should be checked and treated by a specialist rather than a GP. Of course, this depends on access to a professional. Ganglia can descend deeper toward the joints, and simply sucking off the fluid alone is pointless in the long term. While local anaesthetics will often be deployed sometimes, because of difficulties in anaesthetising the deeper tissue, a general anaesthetic is usually preferred.

Use of a Bible - and an Old Wives' Tale

Hitting a ganglion with a heavy book will reduce the swelling as the thin lining collapses. A heavy book might have worked if the additional trauma had not led to bone fractures. Reformation of any membrane can occur if the derivative tissue remains because it has not been removed.

Many ganglia do resolve and absorb, so surgery is not essential in all cases. Another type of swelling that can arise is called a bursa.

Bursal Cyst

The bursa is a type of cyst that can form in the foot to protect tendons, such as the achilles tendon, where a fluid sac lies between the tendon and the heel bone. The deep anatomical bursa can become inflamed, but it settles if the area is not irritated.

An adventitious bursa forms from tissue damage caused by pressure and is commonly seen on the sole. Inside, an unpleasant blood-stained material can ooze out and, when examined under a microscope, inflammatory cells are shown to be active.

Unlike a ganglion, a bursa is not easy to spot from the outside. Those with experience will usually use an ultrasound image, as these are not picked up with an X-ray. A ganglion is often balloon-like and spongy to feel, and tends to be on the upper part of the foot, while a bursa is found on the sole.

Deeper bursae do well from injections, where they form part of normal anatomy, while chronic bursae do not on account of becoming established. Small swellings often do not bother us, but those that are unsightly and cause shoe-fitting problems start to niggle.

If it doesn’t hurt, doesn’t get bigger, or interfere with life, leave it alone.

Mucoid cyst

The mucoid cyst has mucinous fluid content and affects small digital joints (interphalangeal spaces), forming the characteristic swelling that can be taken as an arthritic (Heberden’s node). It does not mean someone has arthritis, but it remains a common finding in feet and hands.

A second opinion should evaluate any swelling in the foot that enlarges. This opinion should be sought from medical doctors or medically trained people, such as specialist podiatrists.