T — primary tumour (Breslow thickness / ulceration)
T1a — < 0.8 mm, no ulceration
T1b — < 0.8 mm with ulceration, or 0.8–1.0 mm (± ulceration)
T2a — > 1.0 to 2.0 mm, no ulceration
T2b — > 1.0 to 2.0 mm, ulcerated
T3a — > 2.0 to 4.0 mm, no ulceration
T3b — > 2.0 to 4.0 mm, ulcerated
T4a — > 4.0 mm, no ulceration
T4b — > 4.0 mm, ulcerated
N — regional nodes / in-transit disease
N0 — no regional node or in-transit disease
N1a — 1 clinically occult node (detected by sentinel biopsy)
N1b — 1 clinically detected node
N1c — no nodes, but microsatellite / satellite / in-transit metastasis
N2a — 2–3 clinically occult nodes
N2b — 2–3 nodes, at least one clinically detected
N2c — 1 node (occult or detected) plus in-transit / satellite disease
N3a — ≥ 4 clinically occult nodes
N3b — ≥ 4 nodes (≥ 1 detected), or any matted nodes
N3c — ≥ 2 nodes and/or matted nodes, plus in-transit / satellite disease
Evidence
Original publication
Gershenwald JE, Scolyer RA, Hess KR, et al. Melanoma staging: evidence-based changes in the AJCC eighth-edition cancer staging manual. T1 was split at 0.8 mm, mitotic rate was removed from T staging, N categories were expanded for microsatellites/in-transit disease, and M1d (CNS) was added; stage III was resolved into IIIA–IIID.
CA: A Cancer Journal for Clinicians, 2017
Guideline
Amin MB, Edge SB, Greene FL, et al., eds. AJCC Cancer Staging Manual, 8th edition. Chicago: Springer; 2017. This tool uses the pathological stage table; the clinical stage table differs. The stage III sub-groups are intricate — confirm against the manual.
Last reviewed: 2026-09
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MedScore is an educational and clinical decision-support tool. It does not provide a diagnosis, a treatment, or a drug-dosing recommendation, and it does not replace clinical judgement or local guidelines. Confirm every result against the original source before acting on it. The treating clinician remains responsible for all decisions.