Discovering a lump on the foot or ankle can be alarming — but the vast majority of foot and ankle masses are benign. The most common is a ganglion cyst, followed by plantar fibromas, lipomas, and bursae. Rarely, a soft tissue mass may represent a more significant finding requiring further workup. At Balance Foot & Ankle in Southeast Michigan, Dr. Tom Biernacki evaluates foot and ankle masses systematically to provide accurate diagnosis and appropriate management.
Ganglion Cysts of the Foot and Ankle
A ganglion cyst is a benign, fluid-filled sac originating from a joint capsule or tendon sheath. On the foot, common locations include the dorsum (top) of the foot over the midtarsal or tarsal joints, around the ankle (particularly the anterior ankle), and adjacent to toe joints. The cyst contains thick, gelatinous fluid similar to joint fluid. Ganglions may fluctuate in size — growing with activity and shrinking with rest — and may be painful (from pressure on adjacent nerves or joint irritation), painless but cosmetically bothersome, or entirely asymptomatic. Diagnosis is clinical with ultrasound confirmation in ambiguous cases.
Other Common Foot Masses
Plantar fibromas are firm, non-movable nodules within the plantar fascia on the sole of the foot — distinct from ganglions and not connected to joint spaces. They can be solitary or multiple (Ledderhose disease) and range from asymptomatic to significantly painful with weight-bearing. A lipoma is a soft, freely mobile, fatty tumor that can occur anywhere on the foot including the heel fat pad. Bursae — fluid-filled sacs that develop in response to friction or pressure — form at predictable locations over bony prominences (retrocalcaneal bursa at the Achilles insertion, submetatarsal bursae). Epidermal inclusion cysts result from traumatic implantation of skin cells beneath the surface. Fibrous histiocytoma and, rarely, synovial sarcoma or other malignancies must be considered when masses are firm, deep, rapidly growing, or poorly defined on imaging.
Treatment Options
Asymptomatic ganglion cysts require no treatment — simple observation is appropriate, as up to 50% resolve spontaneously. Symptomatic cysts can be aspirated under ultrasound guidance, draining the gelatinous contents; however, recurrence rates after aspiration are 50–80%. Surgical excision with removal of the cyst stalk and joint attachment is definitive and has lower recurrence rates (10–20%). Plantar fibromas are managed with padding to offload the nodule, steroid injection for pain reduction, or surgical excision in symptomatic cases — though recurrence is common. Any mass with features suspicious for malignancy (firm, deep, rapidly growing, poorly marginated on ultrasound) is referred for MRI and biopsy.
Frequently Asked Questions
How do I know if a lump on my foot is a ganglion cyst?
Ganglion cysts on the foot are typically smooth, round, fluctuant (squishy), and translucent under direct light — features that help distinguish them from solid tumors. They are most common on the top of the foot over joints. A podiatrist can confirm the diagnosis with ultrasound in minutes and determine whether treatment is needed.
Is it dangerous to leave a ganglion cyst untreated?
Benign ganglion cysts are not dangerous and do not transform into cancer. If the cyst is asymptomatic, observation is a completely reasonable option. Many ganglion cysts resolve on their own. Treatment is recommended when the cyst is painful, limits footwear use, or compresses adjacent nerves causing tingling or numbness.
What is a plantar fibroma and is it serious?
A plantar fibroma is a benign fibrous nodule within the plantar fascia. It is not cancerous but can be painful with walking. It does not resolve on its own. Conservative management (padding, orthotics, steroid injection) reduces pain; surgical excision is reserved for symptomatic nodules that fail conservative care, keeping in mind recurrence is common after surgery.
When should I be worried about a lump on my foot?
See a podiatrist promptly if a foot lump is: rapidly growing, firm and fixed (not movable), deep and poorly defined, associated with skin discoloration or ulceration, painful at rest or at night, or is accompanied by systemic symptoms like weight loss or fatigue. While the vast majority of foot lumps are benign, these features warrant further evaluation with MRI and possible biopsy.
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A new lump on your foot deserves a professional evaluation. Contact Balance Foot & Ankle to schedule with Dr. Biernacki in Southeast Michigan for an accurate diagnosis.
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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.