Medically reviewed by Dr. Tom Biernacki, DPM
Board-certified podiatric surgeon | Balance Foot & Ankle, Howell & Bloomfield Township, MI
Last reviewed: May 2026
Balance Foot & Ankle offers same-week appointments for urgent foot and ankle conditions across Southeast Michigan — but the most important factor in outcomes isn’t getting seen quickly. Our podiatrists explain what to do in the first 24-48 hours before your appointment that most patients skip entirely. Call (810) 206-1402 — expert podiatric care across Michigan.
| Mass Type | Location | Clinical Features | Imaging | Treatment |
|---|---|---|---|---|
| Ganglion Cyst | Dorsal foot (naviculocuneiform); ankle; plantar | Soft, fluctuant, transilluminates; may wax and wane | MRI: simple cyst (homogeneous, T2 bright) arising from joint or tendon sheath | Aspiration (50% recurrence); surgical excision (5–15% recurrence) |
| Plantar Fibroma | Plantar fascia (medial cord) | Firm, non-mobile; attached to fascia; tender with walking | MRI: fusiform mass within plantar fascia; low T2 signal | Custom orthotics; steroid injection; wide excision (20–50% recurrence) |
| Lipoma | Plantar or dorsal soft tissue | Soft, mobile, compressible; usually painless | MRI: characteristic fat signal (T1 bright) | Marginal excision if symptomatic; low recurrence with complete excision |
| Giant Cell Tumor (Tendon Sheath) | Toe tendon sheath; dorsal foot | Firm, lobulated; may cause bone erosion; slow-growing | MRI: low T1/T2 signal (hemosiderin); adjacent bone erosion possible | Surgical excision; 10–20% recurrence; diffuse type higher recurrence |
| Soft Tissue Sarcoma | Any location; deep; >5cm | Firm; deep; growing; painless often until large; deep to fascia | MRI: heterogeneous mass; deep to fascia; contrast enhancement; irregular margins | Wide excision margins; oncology referral; possible radiation adjuvant |
| Red Flag | Significance | Required Action |
|---|---|---|
| Size >5cm | Malignancy risk increases significantly above 5cm | MRI with contrast; oncology or musculoskeletal radiology referral before biopsy |
| Deep to Fascia | Superficial masses are rarely malignant; deep masses have higher malignancy rate | MRI to characterize depth; biopsy protocol |
| Rapid Growth | Growing mass — especially doubling in size over weeks to months | Urgent MRI; expedited biopsy |
| Firm, Fixed, Non-mobile | Suggests infiltrative growth pattern rather than encapsulated benign lesion | Do NOT attempt FNA; core needle or excisional biopsy with orthopedic oncology |
| Bone Erosion on Imaging | Locally aggressive benign (giant cell) or malignant process | MRI + CT; oncology referral; staged biopsy before definitive excision |
| History of Malignancy | Metastasis must be excluded | Bone scan / PET-CT; biopsy before any local treatment |
Medically Reviewed | Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle, Michigan
Evaluating a Lump or Mass in the Foot or Ankle
Discovering a mass or lump in the foot or ankle can be alarming — but the vast majority are benign. The most common foot and ankle soft tissue masses include ganglion cysts (most common), lipomas, plantar fibromas, giant cell tumors of tendon sheath, epidermoid inclusion cysts, and accessory muscles. Rare but important diagnoses include synovial sarcoma, clear cell sarcoma, and other soft tissue sarcomas — which are more common in the foot and ankle than in most other body regions. At Balance Foot & Ankle, Dr. Tom Biernacki evaluates every foot and ankle mass with appropriate imaging and applies oncological surgical principles for any mass that cannot be confidently identified as benign.
Common Benign Foot and Ankle Masses
Ganglion cysts arise from joint capsules or tendon sheaths and contain thick gelatinous fluid — they transilluminate (light passes through them) and are the most common soft tissue mass in the foot. Lipomas are collections of mature fat cells — soft, lobulated, freely mobile, and usually painless. Plantar fibromas are firm, non-mobile nodules within the plantar fascia — they are locally aggressive and have a meaningful recurrence rate after excision. Giant cell tumors of tendon sheath are the second most common hand tumor and are also common in the foot — firm, non-painful, and arise adjacent to tendons.
When Should a Foot Mass Be Urgently Evaluated?
Seek prompt evaluation for any foot or ankle mass that: is rapidly growing; is painful without trauma; is firm or rock-hard; is larger than 5 cm; is deep to the plantar fascia or beneath the dorsal fascia; has overlying skin changes; or is associated with neurological symptoms (numbness, tingling). These features raise concern for a potentially malignant process. Dr. Biernacki does not perform excision-first on any foot mass without appropriate imaging — a guiding principle of oncological surgery that prevents inadvertent violation of tumor margins in potentially malignant lesions.
Imaging Evaluation: Ultrasound and MRI
Dr. Biernacki uses musculoskeletal ultrasound as the first-line imaging tool for foot and ankle masses — it provides real-time characterization (cystic vs. solid, vascular vs. avascular), precise localization, and can guide aspiration or biopsy. MRI is the gold standard for deep or large masses, providing critical information about tissue composition, compartmental involvement, and vascular anatomy for surgical planning. When imaging characteristics are equivocal or concerning for malignancy, Dr. Biernacki refers to an orthopedic oncology center for staging workup and planned biopsy before any excisional surgery.
Surgical Excision Principles
For clearly benign masses (ganglion cysts, confirmed lipomas, epidermoid cysts), Dr. Biernacki performs excision in the office or outpatient surgery center under local or regional anesthesia. For plantar fibromas, wide excision including a margin of plantar fascia is performed to reduce recurrence — simple shelling-out has an unacceptably high recurrence rate. For any mass with imaging features that cannot exclude malignancy, appropriate staging and planned biopsy precede definitive surgery. Dr. Biernacki prioritizes getting the right diagnosis before operating — not just removing whatever is there.
Dr. Tom's Product Recommendations
Frida Plantar Fascia Massage Ball
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Textured massage ball for plantar fascia stretching — useful for plantar fibroma patients who benefit from gentle massage and mobility exercises between clinic visits.
Dr. Tom says: “”My podiatrist recommended this massage ball to help maintain plantar fascia mobility after my fibroma excision.” — Michigan patient”
Plantar fibroma patients maintaining plantar fascia mobility with gentle massage during conservative management
Those with active wounds or post-surgical incisions where pressure over the surgical site is contraindicated
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Silipos Gel Donut Pad
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Donut-shaped gel pad that offloads a plantar fibroma or other plantar mass from direct shoe pressure during ambulation.
Dr. Tom says: “”This pad provided immediate relief from the shoe pressure on my plantar fibroma — recommended by my podiatrist.” — Balance Foot & Ankle patient”
Patients with symptomatic plantar fibroma or other plantar mass who need pressure offloading during shoe wear
Those with post-surgical plantar wounds — pad placement over open wounds is contraindicated
Disclosure: We earn a commission at no extra cost to you.
✅ Pros / Benefits
- Imaging-first approach prevents inadvertent violation of potentially malignant margins
- Ultrasound provides real-time mass characterization and biopsy guidance
- Wide local excision for plantar fibroma reduces recurrence vs. simple enucleation
- Oncology referral for indeterminate or suspicious masses ensures safe management
❌ Cons / Risks
- Plantar fibroma has meaningful recurrence rate even with wide excision
- Some malignant soft tissue tumors of the foot and ankle present as seemingly benign masses
- Foot sarcoma requires referral to orthopedic oncology center for definitive staging and treatment
- Post-excision wound complications are more common in the plantar foot due to wound tension
Dr. Tom Biernacki’s Recommendation
I have a strict rule: I don’t excise any foot or ankle mass without appropriate imaging first. The foot and ankle is actually one of the higher-risk sites for soft tissue sarcoma — particularly synovial sarcoma and clear cell sarcoma — and the consequences of improperly treating a malignant mass are devastating. Get the MRI, characterize the mass, and then plan the surgery appropriately. Most masses are benign and easily treated — but we need to be certain before we cut.
— Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle
Frequently Asked Questions
Is a lump in my foot cancer?
The vast majority of foot and ankle lumps are benign — ganglion cysts, lipomas, and plantar fibromas account for the overwhelming majority of cases. However, the foot and ankle has a higher relative incidence of soft tissue sarcoma than most sites, so any mass deserves proper imaging evaluation before excision. Dr. Biernacki evaluates every mass with ultrasound and MRI as appropriate before surgery.
What does a ganglion cyst feel like?
A ganglion cyst typically feels like a smooth, round, soft-to-firm lump that may fluctuate in size. It transilluminates (light passes through it) and arises adjacent to a joint or tendon sheath. On the dorsum of the foot, ganglion cysts are the most common mass and are usually easily diagnosed by experienced clinical examination and ultrasound.
Do plantar fibromas need to be removed?
Not always — small, asymptomatic plantar fibromas may simply be monitored. Corticosteroid injection can reduce size and symptoms in some cases. Surgical excision is recommended for painful, enlarging, or functionally limiting fibromas. Wide local excision with plantar fascia margin provides lower recurrence rates than simple enucleation, but recurrence remains possible in all cases.
Can a foot lump be biopsied in the office?
Yes — ultrasound-guided needle biopsy (core needle biopsy) of suspicious foot and ankle masses can be performed in the office to obtain a tissue diagnosis before definitive surgical planning. This approach is particularly important for masses with indeterminate imaging characteristics that may require oncological consultation before excision.
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Dr. Tom Biernacki, DPM is a board-certified foot & ankle surgeon (ABFAS & ABPM) 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 made him one of the most-followed foot & ankle educators on YouTube.
More questions patients ask
What are the most common soft tissue masses found in the foot and ankle?
Soft tissue masses in the foot and ankle encompass a wide spectrum from benign reactive lesions to malignant tumors -- the vast majority (greater than 90%) of foot and ankle soft tissue masses are benign, but the anatomical location (close to tendons, neurovascular structures, and bone) makes accurate diagnosis and management essential; the most common benign masses must be distinguished from the rarer but life-threatening malignant lesions. Most common benign foot and ankle soft tissue masses: Ganglion cyst (the most common foot soft tissue mass): a cystic swelling filled with thick, gelatinous fluid arising from a joint capsule or tendon sheath; common locations: dorsal foot (from the tibiotalar or tarsonavicular joint), sinus tarsi, posterior ankle; transilluminates with a pen light; MRI appearance: homogeneous T2 bright signal, thin wall, no solid component; treatment: aspiration or surgical excision; Plantar fibroma (plantar fibromatosis): a firm, non-tender nodule in the central plantar fascia; typically 1-3 cm; does not transilluminate; MRI: low T2 signal (fibrous tissue); treatment: orthotics (accommodative), surgical excision (high recurrence rate); Giant cell tumor of tendon sheath (GCTTS): yellow-brown lobulated mass adherent to a tendon sheath; the second most common foot soft tissue tumor; most common on the plantar aspect adjacent to the flexor tendons; MRI: low T1 and T2 signal (hemosiderin); treatment: surgical excision; Lipoma: soft, compressible fatty mass; common in the heel pad and plantar foot; MRI: identical signal to subcutaneous fat on all sequences; treatment: observation or excision; Epidermoid inclusion cyst: forms after skin trauma drives epidermis beneath the surface; common on the plantar foot (from penetrating injury); Neuroma (Morton's neuroma): painful fusiform enlargement of the interdigital nerve in the third web space; not a true tumor -- represents perineural fibrosis; treatment: corticosteroid injection, surgical excision; Soft tissue sarcoma red flags (when to be concerned): size greater than 5 cm; deep to the fascia; rapid growth; firm, non-mobile, attached to deep structures; recurrence after presumed benign excision; MRI features suggesting malignancy: heterogeneous signal, internal necrosis, surrounding edema, bone involvement.
How is a foot or ankle soft tissue mass evaluated and when is biopsy needed?
Soft tissue mass evaluation follows a systematic approach: clinical assessment, followed by MRI as the imaging gold standard, and then biopsy when malignancy cannot be excluded -- the critical principle is that all masses greater than 5 cm, all deep (subfascial) masses, and any mass with MRI features suggesting malignancy must be referred to a musculoskeletal oncologist before excision; inadvertent excision of a sarcoma through a poorly planned incision contaminates tissue planes and can compromise curative resection. Clinical assessment: history: duration (long-standing benign vs. rapidly growing concerning); prior trauma; systemic symptoms (weight loss, night sweats -- systemic malignancy); medications (phenytoin causes gingival and plantar fibromatosis); examination: size, depth (subcutaneous vs. deep to fascia), consistency (soft/fluctuant vs. firm/hard), mobility, tenderness, overlying skin changes; Imaging: ultrasound: first-line for distinguishing cystic (ganglion, inclusion cyst) from solid lesions and for guiding aspiration or biopsy; MRI without and with gadolinium contrast: the gold standard; characterizes the mass by its relationship to deep structures, tissue signal characteristics (fat, fluid, fibrous, vascular), and enhancement pattern (contrast-enhancing solid lesions are more concerning); MRI cannot definitively distinguish benign from malignant based on signal alone for all masses -- biopsy is required for histological diagnosis when malignancy is possible; When to biopsy: any subfascial solid mass; any mass greater than 5 cm; any mass with heterogeneous MRI signal or internal enhancement suggesting vascularity; any mass whose imaging characteristics do not match a specific benign diagnosis; rapidly growing masses; Biopsy technique (the most critical step): needle (core or fine needle) biopsy under ultrasound or CT guidance by an interventional radiologist; the biopsy tract must be planned so it can be excised en bloc with the tumor during definitive surgery; excisional biopsy (removing the mass without prior needle biopsy) is appropriate ONLY for masses that are clearly superficial, less than 5 cm, and have imaging characteristics consistent with a specific benign diagnosis (ganglion, lipoma, inclusion cyst); for all other masses, excisional biopsy without tissue diagnosis risks contaminating the surgical field if a sarcoma is found -- this is the unplanned excision problem that forces more radical re-excision; Treatment after diagnosis: benign lesions: marginal excision; ganglion cysts recur in 5-15%; plantar fibromas recur in 20-50% requiring wider excision; sarcomas: wide excision with negative margins (2 cm soft tissue margins) combined with radiation therapy; referral to a musculoskeletal oncology center.
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