Stage 0 (Tis, N0, M0) - the earliest stage, the tumour is located in the epidermis without penetrating the dermis.
IA stage (T1a, N0, M0)-the malignant neoplasm is thinner than 1 mm, the melanoma is not erupting. The rate of metastasis is less than 1/mm2.
IB stage (T1b or T2a, N0, M0)-the malignant neoplasm is thinner than 1 mm, it is excised, the speed of metastases is less than 1/mm2. Also in this stage, melanoma can be undeveloped, but thickness can reach 1.01 to 2.00mm.
Stage IIA (T2b or T3a, N0, M0)-The melanoma can range in thickness from 1.01 to 2.0 mm, and is erupted. Also melanoma can be 2.01 to 4.00 mm thick, but not removed.
Stage IIB (T3b or T4a, N0, M0) - melanoma can be 2.01 to 4.00 thick, but the lesion is excised. Thickness of neoplasm can be greater than 4.00 mm, but it is not withdrawn.
Stage IIC (T4b, N0, M0) - The melanoma is 4 mm thick and not excised. No lymph node or distal organ involvement.
Stage IIIA (T1a to T4a, N1a or N2a, M0)- melanoma is any thickness, not withdrawn. 1-3 lymph nodes adjacent to the affected skin area are affected. Melanoma is only visible when viewed closely under a microscope. No distant metastases.
Stage IIIB:
-T1b to T4b, N1a or N2a, M0 - melanoma any thickness, pitting. 1-3 lymph nodes adjacent to the affected skin area are affected. Melanoma is only visible with close microscopic examination. No distant metastases.
-T1a to T4a, N1b or N2b, M0- 1 to 3 lymph nodes adjacent to the affected skin area are affected. Melanoma is only visible when viewed closely under a microscope. No distant metastases.
-T1a to T4a, N2c, M0 Melanoma of any thickness, not withdrawn. Melanoma spreads to the surrounding skin or possibly to lymphatic channels adjacent to the neoplasm. Lymph nodes are not affected. No distant metastases.
Stage IIIC:
-T1b to T4b, N1b or N2b, M0. Melanoma at this stage is withdrawn, with any thickness. 1-3 regional lymph nodes are affected. Enlargement of lymph nodes is seen. No distant metastases.
-T1b to T4b, N2c, M0. Melanoma is erupted, any thickness. In this case, it has spread to the lymphatic channels adjacent to the tumour and to adjacent skin areas. Regional lymph nodes are not affected. No distant metastases.
-Any T, N3, M0. The melanoma may or may not be erupting and its thickness could be variable. It has already spread to 4 or more regional lymph nodes. It may also spread to lymphatic ducts near the neoplasm and to nearby skin areas. Lymph nodes are enlarged. No distant metastases.
Stage IV:
Any T, any N, M1(a, b, or c). Distant metastases are detected.