What Is a Ganglion Cyst?

A ganglion cyst is a benign fluid-filled sac that arises from a joint capsule or tendon sheath. The cyst is filled with thick, gelatinous fluid — essentially an outpouching of the synovial tissue that lines joints and tendon sheaths. Ganglion cysts are among the most common soft tissue masses seen in the foot and ankle, and while they are benign and not cancerous, they can cause significant pain, pressure, and limitation depending on their location and size.

Common Locations in the Foot and Ankle

The most common location for a foot ganglion cyst is the dorsum (top) of the foot, typically arising from the talonavicular or tarsal joints. These cysts present as firm, rounded bumps on the top of the foot that may enlarge with activity and reduce with rest as joint fluid dynamics change. Ankle ganglion cysts arise from the anterior or posterior ankle joint capsule or from the peroneal tendon sheath on the lateral ankle. Plantar (bottom of foot) ganglion cysts are less common but particularly painful because they are directly compressed with every step.

Causes and Risk Factors

Ganglion cysts develop through one of two mechanisms. Joint ganglions form when the joint capsule herniates outward, creating a pedicle through which synovial fluid accumulates in the cyst cavity. Tendon sheath ganglions develop from the mucoid degeneration of the tendon sheath tissue itself. Repetitive joint stress, prior injury, underlying joint degeneration, and hypermobile joint mechanics all contribute to ganglion cyst development. However, many patients develop ganglion cysts without any identifiable precipitating factor.

Symptoms

Many ganglion cysts are asymptomatic and are discovered incidentally when the patient notices a lump. Symptomatic cysts cause localized pain and tenderness — from direct pressure if the cyst is on a weight-bearing surface, or from shoe friction if on the dorsum. Cysts adjacent to nerves can cause tingling or numbness in the distribution of the compressed nerve. Very large cysts or those located at joint spaces may limit range of motion.

Diagnosis

Clinical examination identifies the characteristic firm, transilluminating mass. When a light source is placed against the cyst, the fluid within it illuminates — a feature that helps distinguish ganglion cysts from solid tumors. Ultrasound provides rapid, in-office confirmation of the cystic nature of the mass and assesses the cyst connection to the underlying joint or tendon. MRI is used when the diagnosis is uncertain or when deeper or more complex cysts require anatomic characterization before treatment.

Treatment Options

Observation

Asymptomatic ganglion cysts that are not enlarging, not causing pain, and not restricted by footwear can be observed without intervention. Some cysts spontaneously resolve over months to years. A baseline ultrasound documents cyst size for monitoring purposes. If the cyst grows or becomes symptomatic, active treatment is initiated.

Aspiration

Aspiration — draining the cyst fluid with a needle — is an office procedure that can be performed with or without ultrasound guidance. Ultrasound-guided aspiration is more accurate, particularly for deeper or less accessible cysts. Aspiration provides immediate reduction in cyst size and pain, but the recurrence rate is approximately 50 percent as the cyst pedicle remains and the fluid re-accumulates. Aspiration with corticosteroid injection may reduce recurrence rates compared to aspiration alone.

Surgical Excision

Surgical excision removes the entire cyst including its pedicle connection to the joint or tendon sheath, providing the lowest recurrence rate — approximately 5 to 15 percent compared to 50 percent for aspiration. The procedure is performed as an outpatient under local or regional anesthesia through a small incision overlying the cyst. Recovery involves two to three weeks of protective dressing and activity modification, followed by progressive return to footwear. The recurrence rate is lower when the entire pedicle is excised versus the cyst alone.

When to See a Podiatrist for a Foot Lump

Any new lump on the foot or ankle — regardless of whether it is painful — should be evaluated by a podiatrist to confirm the diagnosis. While most foot lumps are benign ganglion cysts, lipomas, or benign bone growths, occasional soft tissue tumors in the foot require timely diagnosis. Contact Balance Foot & Ankle for evaluation of any new foot or ankle mass.

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Dr. Tom Biernacki, DPM

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.