2002 American Joint Committee on Cancer (AJCC) TNM Staging System for Melanoma

Tx: Primary tumor cannot be assessed (e.g., shave biopsy or regressed melanoma)
T0: No evidence of primary tumor
Tis: Melanoma in Situ
T1: Melanoma <1.0 mm in thickness with or without ulceration
  T1a: Melanoma < 1.0 mm in thickness and level II or III, no ulceration
  T1b: Melanoma <1.0 mm in thickness and level IV or V or with ulceration
T2: Melanoma 1.01 -- 2.0 mm in thickness with or without ulceration
  T2a: Melanoma 1.01 -- 2.0 mm in thickness, no ulceration
  T2b: Melanoma 1.01 -- 2.0 mm in thickness, with ulceration
T3: Melanoma 2.01 -- 4.0 mm in thickness with or without ulceration
  T3a: Melanoma 2.01 -- 4.0 mm in thickness, no ulceration
  T3b: Melanoma 2.01 -- 4.0 mm in thickness, with ulceration
T4: Melanoma > 4.0 mm in thickness with or without ulceration
  T4a: Melanoma > 4.0 mm in thickness, no ulceration
  T4b: Melanoma > 4.0 mm in thickness, with ulceration

NX: Regional lymph nodes cannot be assessed
N0: No regional lymph node metastasis
N1: Metastasis in one lymph node
  N1a: Clinically occult (microscopic) metastasis
  N1b: Clinically apparent (macroscopic) metastasis
N2: Metastasis in two or three regional nodes or intralymphatic regional metastasis without nodal metastases
  N2a: Clinically occult (microscopic) metastasis
  N2b: Clinically apparent (macroscopic) metastasis
  N2c: Satellite or in-transit metastasis without nodal metastasis
N3: Metastasis in four or more regional lymph nodes, or matted metastatic nodes, or in-transit metastasis or satellite(s) with metastasis in regional node(s)

MX: Distant metastasis cannot be assessed
M0: No distant metastasis
M1: Distant metastases
  M1a: Metastasis to skin or subcutaneous tissue or distant lymph nodes
  M1b: Metastasis to lung
  M1c: Metastasis to all other visceral sites or distant metastasis at any site associated with an elevated serum lactic dehydrogenase (LDH)

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