Malignant Melanoma Staging 

Updated: Oct 01, 2015
  • Author: Winston W Tan, MD, FACP; Chief Editor: Dirk M Elston, MD  more...
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TNM Classification for Malignant Melanoma

The TNM classification for malignant melanoma is provided below. [1, 2]

Table. TNM Classification for Malignant Melanoma (Open Table in a new window)

Primary tumor (T)
TX Primary tumor cannot be assessed (ie, curettaged or severely regressed melanoma)
T0 No evidence of primary tumor
Tis Melanoma in situ
T1 Melanoma ≤1.0 mm in thickness
  • T1a: Without ulceration and mitoses < 1/mm 2
  • T1b: With ulceration or mitoses ≥ 1/mm 2
T2 Melanomas 1.01-2.0 mm in thickness
  • T2a: Without ulceration
  • T2b: With ulceration
T3 Melanomas 2.01-4.0 mm in thickness
  • T3a: Without ulceration
  • T3b: With ulceration
T4 Melanomas > 4.0 mm in thickness
  • T4a: Without ulceration
  • T4b: With ulceration
Regional lymph nodes (N)
NX Patients in whom the regional nodes cannot be assessed (ie, previously removed for another reason)
N0 No regional metastases detected
N1-3 Regional metastases based upon number of metastatic nodes and presence or absence of intralymphatic metastases (in transit or satellite metastases)
N1 1 lymph node
  • N1a: Micrometastases
  • N1b: Macrometastases
N2 2 or 3 lymph nodes
  • N2a: Micrometastases
  • N2b: Macrometastases
  • N2c: In-transit met(s)/satellite(s) without metastatic lymph nodes
N3 ≥ 4 metastatic lymph nodes, or matted lymph nodes, or in-transit met(s)/satellite(s) with metastatic lymph node(s)
Distant metastasis (M)
M0 No detectable evidence of distant metastases
M1a Metastases to skin, subcutaneous, or distant lymph nodes, normal serum lactate dehydrogenase (LDH) level
M1b Lung metastases, normal LDH level
M1c Metastases to all other visceral sites or distant metastases to any site combined with an elevated serum LDH level

Anatomic stage/prognostic groups

Table. Clinical staging (Open Table in a new window)

Stage T N M
0 Tis N0 M0
IA T1a N0 M0
IB T1b N0 M0
T2a N0 M0
IIA T2b N0 M0
T3a N0 M0
IIB T3b N0 M0
T4a N0 M0
IIC T4b N0 M0
III Any T N1, N2, or N3 M0
IV Any T Any N M1

Table. Pathologic staging (Open Table in a new window)

Stage T N M
0 Tis N0 M0
IA T1a N0 M0
IB T1b N0 M0
T2a N0 M0
IIA T2b N0 M0
T3a N0 M0
IIB T3b N0 M0
T4a N0 M0
IIC T4b N0 M0
IIIA T(1-4)a N1a M0
T(1-4)a N2a M0
IIIB T(1-4)b N1a M0
T(1-4)b N2a M0
T(1-4)a N1b M0
T(1-4)a N2b M0
T(1-4)a N2c M0
IIIC T(1-4)b N1b M0
T(1-4)b N2b M0
T(1-4)b N2c M0
Any T N3 M0
IV Any T Any N M1

Stage IA:

  • Lesions ≤1 mm in thickness with no evidence of ulceration or metastases (T1aN0M0) are associated with a 5-y survival rate of 95%

Stage IB:

  • Lesions ≤1 mm in thickness with ulceration noted but without lymph node involvement (T1bN0M0) or lesions 1.01-2 mm in thickness without ulceration or lymph node involvement (T2aN0M0) are associated with a 5-y survival rate of approximately 91%

Stage IIA:

  • Melanomas >1 mm but ≤2 mm in thickness with no evidence of metastases but with evidence of ulceration (T2bN0M0) or lesions 2.01-4.0 mm in thickness without ulceration or lymph node involvement (T3aN0M0) are associated with an overall 5-y survival rate of 77-79%

Stage IIB:

  • Melanomas 2.01-4 mm in thickness with ulceration but no lymph node involvement (T3bN0M0) or lesions >4 mm in thickness without ulceration or lymph node involvement (T4aN0M0) are associated with a 5-y survival rate of 63-67%

Stage IIC:

  • Lesions >4 mm in thickness with ulceration but no lymph node involvement (T4bN0M0) are associated with a 5-y survival rate of 45%

Stage IIIA:

  • Patients with any-depth lesion, no ulceration, and 1 positive (micrometastatic) lymph node (T1-4aN1aM0) have a 5-y survival rate of 70%
  • T1-4aN2aM0 lesions (any-depth lesion, no ulceration, but 2-3 nodes positive for micrometastasis) are associated with a 5-y survival rate of 63%

Stage IIIB:

  • Patients with any-depth lesion, positive ulceration, and 1 lymph node positive for micrometastasis (T1-4bN1aM0) or 2-3 nodes positive for micrometastasis (T1-4bN2aM0) have a 5-y survival rate of 50-53%
  • Patients with any-depth lesion, no ulceration, and 1 lymph node positive for macrometastasis (T1-4a, N1b, M0) or 2-3 nodes positive for macrometastasis (T1-4aN2bM0) have a 5-y survival rate of 46-59%

Stage IIIC:

  • Patients with any-depth lesion, positive ulceration, and 1 lymph node positive for macrometastasis (T1-4bN1bM0); 2-3 nodes positive for macrometastasis (T1-4bN2bM0); or ≥4 metastatic lymph nodes, matted lymph nodes, or in-transit met(s)/satellite(s) have a 5-y survival rate of 24-29%

Stage IV:

  • Melanoma metastatic to skin, subcutaneous tissue, or lymph nodes with normal LDH level (M1a) is associated with a 5-y survival rate of 19%
  • M1b disease (metastatic disease to lungs with normal LDH level) has a 5-y survival rate of 7%
  • M1c disease (metastatic disease to all other visceral organs and normal LDH level or any distant disease with elevated LDH level) is associated with a 5-y survival rate of 10%

Mitotic rate assessment

For mitotic rate assessment, the pathologist counts the number of cells in a certain amount of melanoma tissue that are in the process of dividing. A higher mitotic rate means that the cancer is more likely to grow and spread. The mitotic rate is used to stage thin melanoma.