Footworks June 2011
By Alexandra Buk, DPM
“I Have A Knot On The Top Of My Foot!”
Few medical problems are as disconcerting, and worrisome, to patients as “lumps”, cysts or masses under the skin. In fact, I try to avoid the word “tumor” as much as possible when referring to soft tissue masses because of the implication of a cancerous lesion.
By and far, the most common soft tissue mass found on the top or sides of the feet is a ganglion cyst.
Ganglions can occur anywhere on the body, but they are most common on the wrist. The cyst is a mass of tissue filled with a jelly-like fluid called synovial fluid, or joint fluid. Typically synovial fluid is held inside the joint by a covering called the capsule. If something causes the capsule to tear just a little the inside bag of fluid can ooze out and form a ganglion cyst. Early on ganglions typically get larger some days and smaller other days depending on the activity of the joint. After several months they stay pretty much the same size and start to get harder as the fluid gets thicker.
Ganglion cysts on the foot are common and are usually benign. They usually form on the top of the foot, but can develop in other areas as well. I have seen several over the big toe joint that upon initial examination look just like a bunion deformity! In some case the cyst can vanish for a period of time only to reappear later. A ganglion cyst that forms over the smallest joints of the toes are called mucoid cysts.
A ganglion cyst is associated with the following signs and symptoms:
- A noticeable lump on the top of the foot.
- Tingling or burning if the cyst is touching a nerve.
- Dull pain or ache if the cyst is pressing against a tendon or a joint.
- Difficulty wearing shoes due to irritation between the cyst and the shoe.
Some type of injury usually causes ganglion cysts. For example, a ganglion cyst might develop after something drops on the foot, if the foot was twisted while walking, or after too much stress was placed on the joint or tendon. Most patients do not recall the trauma that later triggered this condition.
A simple physical examination helps the doctor to diagnose a ganglion cyst. The lump is usually visually obvious. When the cyst is depressed, it usually moves freely below the surface of the skin and does not adhere to the overlying skin. There may be some associated redness if the cyst is irritated by shoe pressure. X-rays are sometimes taken to
evaluate if any spurs or other associated bone deformities are present. Mucoid cysts are more prevalent in hammertoe deformities.
A small amount of the synovial fluid may be drained after numbing up the area to aid in diagnosis. The cyst is filled with a substance that is very much like hair gel and this gives the doctor a definite diagnosis and the patient peace of mind. If no fluid can be expressed your doctor may order an MRI to more fully evaluate the cyst.
There are various options for treating a ganglion cyst on the foot. If the cyst causes no pain and does not interfere with shoes or walking, you and your podiatrist may decide it’s best to just observe the cyst for a while. Pads can be placed around the cyst to avoid shoe pressure. Most ganglion cysts form on the top of the foot so a lower vamp may help as well.
The ganglion cyst may be completely drained as well, or aspirated, and then injected with a steroid medication to help reduce inflammation. More than one session may be needed.
If all else fails, surgical excision may be necessary. There is a chance of recurrence even if the entire cyst is removed, because it is difficult to always find and repair the original injury to the joint capsule. Sometimes, especially in the case of mucoid cysts in the toes, a piece of the joint needs to be removed or fused to achieve a permanent correction.