A changing pigmented lesion on the sole

Dermoscopic interpretation The combination is highly suspicious for melanoma:

• Atypical pigment network with abrupt cut-off - loss of the normal network at the periphery is a recognised melanoma clue, especially on acral skin.
• Irregular streaks - radial streaming suggests a growing, invasive lesion.
• Blue-white veil - corresponds to orthokeratosis over dermal pigment or melanophages and is a melanoma-associated structure.
• Polymorphous vascular pattern - irregular vessels within a pigmented lesion are a strong clue to malignancy.
• Central regression - can occur in melanoma and can falsely reassure.

On acral skin, the parallel ridge pattern is the classic melanoma pattern, but a parallel furrow pattern is benign; here the pattern is atypical and the overall gestalt is malignant. The nodule at the edge suggests a vertical growth phase.

Immediate pathway

1. Urgent excisional biopsy with 2 mm margins - never a shave or partial biopsy of a suspicious acral lesion, because Breslow thickness and mitotic rate require full-thickness assessment.
2. Histopathology with immunohistochemistry (S100, Melan-A, HMB-45, SOX10) if needed.
3. If melanoma is confirmed, staging: sentinel lymph node biopsy discussion (Breslow >0.8 mm or <0.8 mm with ulceration or mitoses), and imaging (CT or PET-CT) depending on stage. Inguinal nodes are the relevant basin for a heel lesion.
4. Breslow thickness, ulceration, mitotic rate, and lymphovascular invasion drive prognosis and further management.
5. Multidisciplinary team referral for wide local excision planning (1–2 cm margins depending on thickness) and consideration of immunotherapy if node-positive.

Caveats in skin of colour Acral melanoma is more common in darker skin and is frequently diagnosed late. The absence of sunburn history and family history must not lower suspicion. Emphasise that the lesion is on a weight-bearing, trauma-exposed site, which can mimic benign processes and delay diagnosis.

Staging

• Breslow 1.6 mm, non-ulcerated, mitotic rate ≥1/mm²: this is stage IB or IIA depending on the exact T category (T2b = 1.01–2.0 mm without ulceration). Under AJCC 8th edition, T2b is stage IIA if node-negative. Sentinel lymph node biopsy is recommended for Breslow >0.8 mm, so SLNB is indicated here.

Prognosis discussion

• Be honest but calibrated: stage IIA melanoma has a generally favourable prognosis, with 5-year melanoma-specific survival in the region of 80–90% in contemporary series, but recurrence risk is real and follow-up matters.
• Explain that prognosis depends on the final pathology (including any regression, lymphovascular invasion, and the SLNB result) and that statistics describe populations, not individuals.
• Discuss the possibility of recurrence and the importance of self-examination and scheduled follow-up.

Sentinel lymph node biopsy

• Purpose: to identify microscopic nodal disease, which is the strongest prognostic factor and guides adjuvant therapy decisions.
• Procedure: lymphatic mapping with radiolabelled colloid and/or blue dye, excision of the sentinel node(s) under general anaesthetic, with a small risk of seroma, lymphoedema, and nerve injury.
• Outcomes: if negative, no completion lymphadenectomy is needed (MSLT-II showed no survival benefit from completion dissection). If positive, discuss adjuvant systemic therapy (e.g., immune checkpoint inhibitors or BRAF/MEK inhibitors if BRAF-mutant) and surveillance imaging.
• Timing: ideally within 6–8 weeks of the primary excision, and before wide local excision if possible.

Follow-up

• Clinical review every 3–6 months for the first 2–3 years, then less frequently, with imaging as per local protocol.
• Counsel on sun protection, self-examination, and the importance of reporting new or changing lesions, particularly on acral sites.
• Address the psychological impact and the patient's concerns about his foot and walking.