Melanoma Staging System, TNM Definitions

PRIMARY TUMOR
TX: Cannot be assessed (shave biopsy, regressed lesion)
T0: Unknown primary
Tis: In situ melanoma
T1: -1.0 mm Breslow thickness

a. without ulceration

b. with ulceration or Clark level IV or V

T2: 1.01 to 2.0 mm

a. without ulceration

b. with ulceration

T3: 2.01 to 4.0 mm

a. without ulceration

b. with ulceration

T4: more than 4.0 mm

a. without ulceration

b. with ulceration

REGIONAL LYMPH NODE INVOLVEMENT
NX: Cannot be assessed (previously removed)
N0: No regional node metastasis
N1: Metastasis in one regional node

a. micrometastasis (diagnosed by SLNB or elective lymph node dissection)

b. macrometastasis (clinically palpable or found on imaging studies, confirmed histologically, or gross extracapsular extension)

N2: Metastasis in two to three regional nodes

a. micrometastasis

b. macrometastasis

c. in-transit or satellite metastasis without nodal metastasis

N3: Metastasis to regional nodes, matted nodes, or in-transit or satellite metastasis with positive metastatic nodes

DISTANT METASTASIS
MX: Cannot be assessed
M0: No distant metastasis
M1a: Distant skin, subcutaneous, or lymph node metastasis with normal LDH
M1b: Lung metastasis with normal LDH
M1c: All other distant metastasis or any distant site with elevated LDH