Subungual Melanoma: Diagnosis, Nail Biopsy, and Surgical Wide Excision

Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Township, MI. Last updated April 2026.

Subungual melanoma — malignant melanoma arising from the nail matrix or nail bed beneath the toenail or fingernail — accounts for 0.7–3.5% of all melanomas in Caucasians and a disproportionately higher percentage in darker-skinned populations, and is the most commonly misdiagnosed malignancy of the foot due to its resemblance to subungual hematoma, fungal nail infection, and nail dystrophy. Biopsy delay beyond 6–12 months from first clinical suspicion is associated with increased tumor thickness (Breslow depth) and worse prognosis — making early recognition and prompt nail biopsy the critical intervention that saves lives.

Clinical Recognition: Differentiating from Benign Conditions

Subungual melanoma features: longitudinal melanonychia (brown-black longitudinal stripe along the nail) — the key presenting sign; the ‘ABCDEF criteria for nail melanoma’: A = Age (40–70 peak) and African/Asian/Native American ancestry (higher incidence); B = Band width >3mm, lack of Borders (irregular); C = Change in band width or color over time; D = Digit involvement (hallux, thumb, or index finger most common); E = Extension of pigment to the perionychial skin (Hutchinson’s sign — pathognomonic for melanoma); F = Family or personal history of melanoma. Pitfalls: the ‘Pseudo-Hutchinson’s sign’ — periungual pigmentation can occur with subungual hematoma (distinguish by history of trauma and proximal migration of the discoloration). Subungual hematoma: pain at onset, proximal nail growth with clear nail appearing proximally over weeks; subungual melanoma does not migrate proximally. Annual prevalence: subungual melanoma is rare — 25–35 new cases per million per year; but the consequences of missed diagnosis are devastating — 5-year survival with early detection (Stage I) is 80–95% vs. 15–30% with metastatic disease.

Diagnosis and Surgical Management

Nail matrix biopsy (the diagnostic gold standard): longitudinal biopsy technique under digital nerve block; nail plate removed; biopsy through the nail bed/matrix including the full thickness to the periosteum; 3–4mm punch or tangential shave biopsy depending on lesion characteristics; histopathology confirms melanoma diagnosis and establishes Breslow depth. Surgical wide local excision: distal toe or finger amputations are NO LONGER the standard — wide local excision with 1cm margins (for Breslow <1mm) or 2cm margins (>1mm) with sentinel lymph node biopsy is the current evidence-based approach; the digit is preserved when oncologic margins can be achieved. Sentinel lymph node biopsy: performed for Breslow depth >0.8mm; inguinal SLN for hallux melanoma; SLN positivity rate 20–30% for subungual melanoma; positive SLN guides adjuvant immunotherapy. Adjuvant therapy: anti-PD-1 immunotherapy (pembrolizumab, nivolumab) for Stage III–IV disease; targeted therapy (BRAF inhibitors) for BRAF-mutated melanoma. Dr. Biernacki at Balance Foot & Ankle evaluates suspicious nail lesions and performs nail matrix biopsy for subungual melanoma diagnosis at our Bloomfield Township and Howell offices. Call (810) 206-1402.

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Frequently Asked Questions

What is the most effective treatment for toenail fungus?

Oral antifungal medications (terbinafine, itraconazole) have the highest cure rates at 70–80%. Prescription topical treatments (efinaconazole, tavaborole) are safer but slower. Laser treatment is a pain-free option. Complete clearance takes 9–18 months as new nail grows in.

How long does it take to cure toenail fungus?

Fungal nail infections are slow to clear because nails grow slowly. With treatment, you may see initial improvement in 3–4 months, but complete clearance of a toenail takes 9–12 months (toenails grow about 1.5mm per month).

Can toenail fungus spread to other nails or family members?

Yes, fungal infections can spread to adjacent toenails and less commonly to skin (athlete’s foot) or family members through shared surfaces. Using flip-flops in showers, not sharing nail clippers, and treating promptly reduces spread risk.

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Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin see patients at our Howell and Bloomfield Township offices.

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Most Common Mistake We See

The most common mistake we see is: Waiting too long before seeking care. Fix: any foot pain lasting more than 4 weeks, or any sudden severe symptom, deserves a professional evaluation rather than more rest.

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Our podiatry team serves patients throughout Michigan including Howell, Brighton, and Bloomfield Township. If you’re dealing with heel pain, ingrown toenails, or a foot injury, you can book online 24/7.

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