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Skin: AJCC8 melanoma M staging and CNS disease

Free question published 02 October 2026

SkinTNM9 melanoma M staging and CNS disease

A 60-year-old man with a previously resected truncal melanoma re-presents with headache. Staging imaging confirms two cerebral metastases alongside a solitary pulmonary metastasis, and his serum lactate dehydrogenase (LDH) is elevated. There is no other site of disease. Using the current AJCC/UICC TNM classification (TNM9), what is his M category?

  1. AM0
  2. BM1c
  3. CM1b
  4. DM1d
  5. EM1a

Why D is correct

AJCC8 introduced M1d to designate distant metastasis to the central nervous system, with or without concurrent metastases at other anatomic sites; this category is unchanged in TNM9. Because this patient has cerebral (CNS) metastases, his disease is M1d regardless of the coexisting lung metastasis, and the raised LDH is captured by the additional suffix (1) within that stratum.

And why the others are not

  • AIncorrect: M0 indicates no distant metastasis, which is contradicted by the brain and lung deposits.
  • BIncorrect: M1c denotes non-CNS visceral metastasis; CNS disease is now separated out as M1d.
  • CIncorrect: M1b denotes lung metastasis without CNS involvement; the presence of brain metastases takes precedence.
  • EIncorrect: M1a denotes distant skin, soft tissue or non-regional nodal metastases, not CNS disease.

Source AJCC 8th edition melanoma staging - key changes — Gershenwald JE, Scolyer RA, Hess KR, et al. Melanoma staging: Evidence-based changes in the American Joint Committee on Cancer eighth edition cancer staging manual. CA Cancer J Clin. 2017;67(6):472-492.

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