TNM Classification for Malignant Melanoma
The American Joint Committee on Cancer (AJCC) tumor/node/metastasis (TNM) classification and staging system for cancer are provided below. [1, 2]
Table 1. TNM Classification for Malignant Melanoma (Open Table in a new window)
Primary tumor (T) |
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TX |
Primary tumor cannot be assessed (ie, curettaged melanoma) |
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T0 |
No evidence of primary tumor |
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Tis |
Melanoma in situ |
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T1 |
Thickness ≤1.0 mm |
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T1a: < 0.8 mm without ulceration |
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T1b: < 0.8 mm with ulceration, or 0.8-1.0 mm with or without ulceration |
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T2 |
Thickness >1.0-2.0 mm |
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T2a: Without ulceration |
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T2b: With ulceration |
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T3 |
Thickness >2.0-4.0 mm |
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T3a: Without ulceration |
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T3b: With ulceration |
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T4 |
Thickness >4.0 mm |
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T4a: Without ulceration |
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T4b: With ulceration |
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Regional lymph nodes (N) |
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NX |
Regional nodes cannot be assessed (ie, previously removed for another reason) |
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N0 |
No regional metastases detected |
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N1 |
One tumor-involved lymph node or in-transit, satellite, and/or microsatellite meastases with no tumor-involved nodes |
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N1a: One clinically occult (ie, detected by sentinel lymph node biopsy [SLNB]; no in-transit, satellite, or microsatellite metastases |
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N1b: One clinically detected; no in-transit, satellite, or microsatellite metastases |
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N1c: No regional lymph node disease; in-transit, satellite, and/or microsatellite metastases found |
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N2 |
Two or three tumor-involved nodes; or in-transit, satellite, or microsatellite metastases |
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N2a: Two or three clinically occult (ie, detected by SLNB); no in-transit, satellite, or microsatellite metastases |
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N2b: Two or three clinically detected; no in-transit, satellite, or microsatellite metastases |
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N2c: One clinically occult or clinically detected; in-transit, satellite, and/or microsatellite metastases found |
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N3 |
≥4 tumor-inolved nodes or in-transit, satellite, and/or microsatellite metastases with ≥2 tumor-involved nodes or any number of matted nodes without or with in-transit, satellite, and/or microsatellite metastases |
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N3a: ≥4 clinically occult (ie, detected by SLNB); no in-transit, satellite, or microsatellite metastases |
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N3b: ≥4, at least one of which was clinicallly detected, or presence of any matted nodes; no in-transit, satellite, or microsatellite metastases |
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N3c: ≥2 clinically occulr or clinically detected and/or presence of any matted nodes, with presence of in-transit, satellite, and/or microsatellite metastases |
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Distant metastasis (M) |
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M0 |
No detectable evidence of distant metastases |
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M1a |
Metastases to skin, soft tissue (including muscle), and/or nonregional lymph nodes |
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M1b |
Lung metastasis, with or without M1a involvement |
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M1c |
Distant metastasis to non–central nervous system (CNS) visceral sites with or without M1a or M1b involvement |
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M1d |
Distant metastasis to CNS, with or without M1a or M1b involvement |
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Cases of metastasis (beyond M0) in which the lactate dehydrogenase (LDH) level is known are given the suffix (0), for normal LDH level, or (1), for elevated LDH level |
Anatomic stage/prognostic groups
Table 2. 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 |
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IIA |
T2b |
N0 |
M0 |
T3a |
N0 |
M0 |
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IIB |
T3b |
N0 |
M0 |
T4a |
N0 |
M0 |
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IIC |
T4b |
N0 |
M0 |
III |
Any T, Tis |
N1, N2, or N3 |
M0 |
IV |
Any T |
Any N |
M1 |
Table 3. Pathologic staging (Open Table in a new window)
Stage |
T |
N |
M |
0 |
Tis |
N0 |
M0 |
IA |
T1a, T1b |
N0 |
M0 |
IB |
T2a |
N0 |
M0 |
IIA |
T2b, T3a |
N0 |
M0 |
IIB |
T3b, T4a |
N0 |
M0 |
IIC |
T4b |
N0 |
M0 |
IIIA |
T1a/b, T2a |
N1a, N2a |
M0 |
IIIB |
T0 |
N1b, N1c |
M0 |
T1a/b, T2a |
N1b/c, N2b |
M0 |
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T2b, T3a |
N1a/b/c, N2a/b |
M0 |
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IIIC |
T0 |
N2b/c, N3b/c |
M0 |
T1a/b, T2a/b, T3a |
N2c, N3a/b/c |
M0 |
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T3b, T4a |
Any N ≥N1 |
M0 |
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T4b |
N1a/b/c, N2a/b/c |
M0 |
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IIID |
T4b |
N3a/b/c |
M0 |
IV |
Any T, Tis |
Any N |
M1 |
Stage IA:
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Lesions ≤1 mm in thickness with no evidence of ulceration or metastases (T1aN0M0) are associated with a 5-y survival rate of ~97%
Stage IB:
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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 ~92%
Stage IIA:
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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 ~81%
Stage IIB:
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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 ~70%
Stage IIC:
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Lesions >4 mm in thickness with ulceration but no lymph node involvement (T4bN0M0) are associated with a 5-y survival rate of ~53%
Stage IIIA:
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Patients with any-depth lesion, no ulceration, and 1 positive (micrometastatic) lymph node (T1-4aN1aM0) have a 5-y survival rate of ~70%
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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:
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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%
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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:
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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 ~40%
Stage IV:
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Melanoma metastatic to skin, subcutaneous tissue, or lymph nodes with normal LDH level (M1a) is associated with a 5-y survival rate of ~15%-20%
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M1b disease (metastatic disease to lungs with normal LDH level) has a 5-y survival rate of 7%
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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.