A 52-year-old man with fair skin and a history of multiple sunburns in childhood presents with a pigmented lesion on his trunk. On examination, the lesion marked **A** in the diagram shows asymmetry, irregular borders with notching, variation in color (brown, black, and red), a diameter of 8 mm, and the patient reports it has been slowly enlarging over the past 6 months. Full-thickness excisional biopsy reveals a lesion with a Breslow depth of 2.5 mm and no ulceration. Which of the following is the most appropriate next step in management?

Explanation

## Why Wide local excision with 2 cm margins followed by sentinel lymph node biopsy is right The lesion marked **A** is a cutaneous melanoma (ABCDE-positive: asymmetry, border irregularity, color variation, diameter >6 mm, evolution). With a Breslow depth of 2.5 mm (T3 stage per AJCC 8th edition: >2.0–4.0 mm), AJCC guidelines mandate wide local excision with 2 cm margins (the standard for tumors >2 mm per Bolognia 5e and AJCC 8th edition). Sentinel lymph node biopsy (SLNB) is indicated for all tumors >0.8 mm or T1b and above, as it provides crucial staging information and prognostic stratification. This patient's depth places him at significant risk for nodal involvement and requires complete staging. ## Why each distractor is wrong - **Topical imiquimod monotherapy without further surgical intervention**: Imiquimod is not a primary treatment for invasive melanoma. It may have a role in lentigo maligna (in situ disease on the face of elderly patients), but a 2.5 mm deep invasive melanoma requires surgical excision and staging, not topical therapy alone. - **Shave biopsy with cauterization of the base to achieve complete removal**: Shave biopsy is explicitly contraindicated in suspicious melanocytic lesions because it disrupts the assessment of Breslow depth and vertical growth phase — the single most important prognostic factor. Full-thickness excisional biopsy (already done here) is the gold standard. Shave removal would be inadequate and dangerous. - **Observation with monthly self-examination and 6-monthly dermatology follow-up only**: While self-examination and regular follow-up are essential components of melanoma surveillance, they are NOT substitutes for surgical management of an invasive melanoma with 2.5 mm depth. Observation alone allows progression to stage III/IV disease and dramatically worsens prognosis. **High-Yield:** Breslow depth >2 mm = wide excision (2 cm margins) + SLNB mandatory; never shave a suspicious lesion; checkpoint inhibitors (nivolumab/pembrolizumab) are adjuvant therapy for stage III node-positive disease. [cite: Bolognia Dermatology 5e Ch 113; AJCC 8th Edition Melanoma Staging]