Melanoma staging — SCE Dermatology MCQ

Correct answer: B — Wide local excision and sentinel node biopsy discussion

The correct answer is B, wide local excision and sentinel node biopsy discussion. A Breslow thickness of 1.2 mm places this melanoma at stage IB (pT2a), above the 1 mm threshold at which NICE recommends offering sentinel lymph node biopsy (SLNB) to patients without clinically or radiologically apparent nodal disease, as staging information guides prognosis and further management. Diagnostic excision only removes the lesion with narrow margins for histological confirmation; it is not definitive treatment, so a formal wide local excision (1 cm margin for tumours up to 2 mm thick) is still required to reduce local recurrence risk. Because there is no palpable lymphadenopathy, SLNB (not therapeutic lymph node dissection) is the appropriate staging discussion, and this must happen before or alongside the definitive excision. Why the other options are wrong: D. Topical imiquimod to the scar: imiquimod has a role in lentigo maligna melanoma in situ where surgery is unsuitable, not in an invasive melanoma with measurable Breslow thickness after clear diagnostic excision. E. Routine discharge after diagnostic excision: this abandons definitive margin clearance and staging, leaving residual risk of local recurrence and undiagnosed nodal micrometastasis untreated. A. Immediate isolated limb perfusion: this is reserved for unresectable locoregional recurrence or in-transit metastasis on a limb, not first-line management of a newly diagnosed 1.2 mm primary melanoma. C. Mohs surgery as the standard approach: Mohs is not standard for cutaneous melanoma in UK practice; wide local excision with defined margins based on Breslow thickness is the guideline-recommended technique. Key point: Breslow thickness above 1 mm (as here at 1.2 mm) mandates both formal wide local excision with an appropriate margin and a sentinel lymph node biopsy discussion, since diagnostic excision alone is never definitive treatment.

Reference: NICE NG14: Melanoma: assessment and management (updated 2022), sections on surgical excision margins and sentinel lymph node biopsy, https://www.nice.org.uk/guidance/ng14