Paediatric melanoma

Melanoma staging system follows the guidelines established by the AJCC (American Joint Committee on Cancer) based on the Tumour, Nodes and Metastasis (TNM) classification and stage grouping criteria¹⁰. This evidence-based system will guide patient treatment, provide better prognostic estimates and refine stratification of patients entering clinical trials.

The T category – Breslow tumour thickness

T category tumour is determined by the thickness of the tumour and if it is ulcerated or not. T0 should be used to designate when there is no evidence of a primary tumour or that the site of the primary tumour is unknown. Tis is the classification for melanoma in situ, melanoma just starts to proliferate but not invasion has happened yet. T1 melanoma is classified when the thick is under 1mm, T2 is between 1 and 2 mm, T3 is comprised between 2 and 4 mm and T4 is when the tumour has invaded more than 4mm vertically. Depending on the ulcerate state of the mole, it will be classified as stage I or II melanoma.

The N category – Regional lymph nodes

N category is representative of the number of lymph nodes around the tumour that have been affected. It is an equivalent of how cells have affected and invaded the lymph vessels and when these are damaged, melanoma is classified as stage III.

The M category – Distant metastatic disease

When the melanoma has spread beyond the original site and regional lymph nodes to more distant areas of the body, it has produced metastasis. The M category is characterized by the number of metastasis (sites affected distant from the primary tumour). The presence of metastasis is equivalent to stage IV melanoma.

¹⁰Gershenwald, J. E. et al. Melanoma staging: Evidence-based changes in the American Joint Committee on Cancer eighth edition cancer staging manual. CA. Cancer J. Clin. 67, 472–492 (2017).