In AJCC 8th edition staging, a patient with a 2.5 mm thick melanoma without ulceration and 2 mitoses per mm² would be classified as which T-stage?

Explanation

## AJCC 8th Edition T-Stage Classification for Melanoma **Key Point:** In AJCC 8th edition, T-stage for melanoma is determined by tumor thickness and ulceration status. Mitotic rate is **no longer used** for T-stage assignment in the 8th edition (it was removed as a staging criterion compared to the 7th edition). ### T-Stage Definitions (AJCC 8th Edition) | T-Stage | Thickness | Ulceration | |---------|-----------|------------| | T1a | < 0.8 mm | No ulceration | | T1b | < 0.8 mm with ulceration, OR 0.8–1.0 mm (with or without ulceration) | — | | T2a | > 1.0–2.0 mm | No ulceration | | T2b | > 1.0–2.0 mm | With ulceration | | T3a | > 2.0–4.0 mm | No ulceration | | T3b | > 2.0–4.0 mm | With ulceration | | T4a | > 4.0 mm | No ulceration | | T4b | > 4.0 mm | With ulceration | ### Applying to This Case - Thickness: **2.5 mm** → falls in the **> 2.0–4.0 mm** range - Ulceration: **Absent** - Mitotic rate: **Irrelevant** for T-stage in AJCC 8th edition → Classification: **T3a** **High-Yield:** The AJCC 8th edition removed mitotic rate from T-stage criteria. A 2.5 mm melanoma without ulceration is **T3a**, not T4a (which requires thickness > 4.0 mm). ### Clinical Pearl **"T3 = 2–4 mm; T4 = > 4 mm"** — The threshold between T3 and T4 is 4.0 mm, not 2.0 mm. This is a commonly tested distinction in NEET PG/INI-CET. Always confirm the edition of AJCC being referenced, as criteria changed between 7th and 8th editions. *Reference: AJCC Cancer Staging Manual, 8th Edition (2017), Chapter 47 — Melanoma of the Skin.*