The sentinel lymph node biopsy (SLNB) in melanoma is recommended for tumours with Breslow thickness of ≥1 mm. The most important single histological prognostic factor in primary melanoma at the time of diagnosis is:

• A Clark's level of invasion
• B Presence of mitoses (mitotic rate/mm²)
• C Tumour-infiltrating lymphocytes (TIL) grade
• D Breslow thickness (tumour depth in mm) ✓

Explanation

Breslow thickness (vertical tumour depth measured from the top of the granular layer to the deepest tumour cell) is the most important independent prognostic factor for melanoma survival in the current AJCC 8th edition staging. Clark's level has been removed from the primary staging criteria and is now used only as an additional criterion for T1 tumours. Mitotic rate ≥1/mm² is now part of T1b staging (upgrading). TIL grade is a favourable prognostic marker but not a primary staging parameter.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.