A 52-year-old man from Mumbai presents with a 6-month history of a gradually enlarging pigmented lesion on his left shoulder. On examination, the lesion measures 8 mm in diameter with irregular borders, color variation (brown, black, and red areas), and a slightly raised surface. Dermoscopy shows asymmetric pigmentation with atypical network pattern. A full-thickness excisional biopsy confirms cutaneous melanoma with Breslow thickness of 2.8 mm, 3 mitoses per mm², and no ulceration. Sentinel lymph node biopsy of the left axilla is negative. CT chest and abdomen are unremarkable. According to the AJCC 8th edition staging system, what is the stage of this melanoma?

Explanation

## AJCC 8th Edition Melanoma Staging **Key Point:** Melanoma staging integrates Breslow thickness, ulceration status, mitotic rate, and nodal/distant metastasis status. The presence of sentinel lymph node involvement determines Stage III classification. ### Prognostic Factors in This Case | Factor | Finding | Significance | |--------|---------|---------------| | **Breslow thickness** | 2.8 mm | T3 (1.01–4.0 mm) | | **Ulceration** | Absent | Favorable | | **Mitotic rate** | 3/mm² | Present (≥1/mm²) | | **Sentinel lymph node** | Negative | N0 (no nodal involvement) | | **Distant metastasis** | None | M0 | ### Stage Assignment Logic 1. **T stage:** Breslow 2.8 mm = T3 (thickness 1.01–4.0 mm without ulceration) 2. **N stage:** Negative sentinel lymph node biopsy = N0 3. **M stage:** No distant metastases = M0 4. **Stage determination:** T3, N0, M0 = **Stage IIB** **High-Yield:** The presence of mitotic rate ≥1/mm² in a non-ulcerated lesion 1.01–4.0 mm thick places this in Stage IIB (not Stage IIA, which requires either ulceration OR thickness 0.8–1.0 mm). **Clinical Pearl:** Sentinel lymph node biopsy is recommended for melanomas ≥0.8 mm thick or with high-risk features (ulceration, high mitotic rate, young age). Negative SLNB confirms N0 status and excludes Stage III disease. **Mnemonic: AJCC T-Staging for Melanoma** - T1: ≤0.8 mm - T2: 0.81–1.0 mm - T3: 1.01–4.0 mm - T4: >4.0 mm (Presence of ulceration or mitotic rate ≥1/mm² upstages within the same thickness category in earlier editions; AJCC 8e uses thickness primarily.) [cite:AJCC Cancer Staging Manual 8th Edition]