Rapidly growing pigmented nodule on the back

T4b nodular melanoma — staging, SLNB and adjuvant therapy decision tree

Learning points

• Nodular melanoma accounts for ~ 10–15% of cutaneous melanoma but a disproportionate share of melanoma deaths because of its vertical growth phase and short symptom-to-diagnosis interval.
• Pigmented nodules ≥ 6 mm or ulcerated, with a history of recent growth, score well on the Williams 7-point checklist and warrant a 2-week-wait NICE NG12 referral.
• AJCC 8 thresholds: T1 boundary at 0.8 mm; ulceration upstages each T category (a/b).
• NICE NG14 margins are stage-based: stage 0 at least 5 mm, stage I 1 cm, stage II 2 cm. In the 1.01–2.0 mm band, ulceration matters because T2a N0 is stage IB (1 cm) whereas T2b N0 is stage IIA (2 cm).
• NICE NG14 §1.4.3–4 says to consider SLNB for Breslow >1.0 mm melanoma after shared discussion; this T4b tumour is therefore in the group where SLNB should be actively discussed at MDT and with the patient. SLN-positive disease no longer mandates completion lymphadenectomy after MSLT-II — observation + adjuvant ICI is the modern standard.
• Adjuvant pembrolizumab (TA837) for resected stage IIB / IIC; adjuvant pembrolizumab (TA766), nivolumab (TA684), or dabrafenib + trametinib for BRAF V600-mutant disease (TA544) for resected stage III; NHS England URN 2426 neoadjuvant pathway is considered at MDT for stage III macroscopic resectable melanoma.