Table 2.

Pathologic or surgical (0 - IV) staging of melanoma.

Stage	Primary Tumor (T)	Regional Lymph Nodes (N)	Distant Metastasis (M)
0	Tis	N0	M0
I	T1a - T2a	N0	M0
II	T2b - T4b	N0	M0
III	T0 - T4b	N1a - N3c	M0
IV	any T	any N	M1

Notes:

Tis: the melanoma cells are only in the very top layer of the skin surface. It is called melanoma in situ.

T0: no melanoma cells can be seen where the melanoma started (primary site).

T1: the melanoma is 1 mm thick or less. It is split into T1a and T1b.

T1a: the melanoma is less than 0.8 mm thick and the skin over the tumour does not look broken under the microscope (not ulcerated).

T1b: either: the melanoma is less than 0.8 mm thick but is ulcerated, or the melanoma is between 0.8 mm and 1.0 mm and may or may not be ulcerated.

T2: the melanoma is between 1 mm and 2 mm thick.

T3: the melanoma is between 2 mm and 4 mm thick.

T4: the melanoma is more than 4 mm thick.

T2 and T4 melanoma is further divided into a and b depending on whether it is ulcerated or not. A means without ulceration, b means with ulceration.

N0: there are no melanoma cells in the nearby lymph nodes.

N1: there are melanoma cells in one lymph node or there are in-transit, satellite or microsatellite metastases.

N2: there are melanoma cells in 2 or 3 lymph nodes or there are melanoma cells in one lymph node and there are also in-transit, satellite or microsatellite metastases.

N3: there are melanoma cells in 4 or more lymph nodes or there are melanoma cells in 2 or 3 lymph nodes and there are in-transit, satellite or microsatellite metastases or there are melanoma cells in any number of lymph nodes and they have stuck to each other (matted lymph nodes).

M0: the cancer hasn't spread to another part of the body.

M1: the cancer has spread to another part of the body. M1 can be further divided depending on which parts of the body the cancer has spread to and whether there are raised levels of a chemical in the blood called lactate dehydrogenase (LDH).