MALIGNANT MELANOMA OF SKIN (ICD‐O‐3 C44, C51.0, C60.9, C63.2)

Rules for Classification

There should be histological confirmation of the disease.

Regional Lymph Nodes

The regional lymph nodes are those appropriate to the site of the primary tumour. See Regional Lymph Nodes under Skin Tumours.

TNM Clinical Classification

T – Primary Tumour

The extent of the tumour is classified after excision, see pT, page 000.

N – Regional Lymph Nodes

NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastasis in one regional lymph node or intralymphatic regional metastasis without nodal metastasis
	N1a	Only microscopic metastasis (clinically occult) (Fig. 357)
	N1b	Macroscopic metastasis (clinically apparent) (Fig. 358)
	N1c	Satellite or in‐transit metastasis without regional nodal metastasis (Figs. 359, 360)
N2	Metastasis in two or three regional lymph nodes or intralymphatic regional metastasis with regional metastasis
	N2a	Only microscopic nodal metastasis (Fig. 361)
	N2b	Macroscopic nodal metastasis (Fig. 362)
	N2c	Satellite or in‐transit metastasis with only one regional nodal metastasis (Fig. 363)
N3	Metastasis in four or more regional lymph nodes (Fig. 364), or matted metastatic regional lymph nodes (Fig. 365), or satellite(s) or in‐transit metastasis with metastasis in regional lymph node(s) (Figs. 366, 367)

Note
Satellites are tumour nests or nodules (macro‐ or microscopic) within 2 cm of the primary tumour. In‐transit metastasis involves skin or subcutaneous tissue more than 2 cm from the primary tumour but not beyond the regional lymph nodes.

Schematic illustration of Only microscopic metastasis. — **Fig. 357**

Schematic illustration of Macroscopic metastasis. — **Fig. 358**

Schematic illustration of Satellite or in-transit metastasis without regional nodal metastasis. — **Fig. 359**

Schematic illustration of Only microscopic nodal metastasis. — **Fig. 361**

Schematic illustration of Macroscopic nodal metastasis. — **Fig. 362**

Schematic illustration of Satellite or in-transit metastasis with only one regional nodal metastasis. — **Fig. 363**

Schematic illustration of Metastasis in four or more regional lymph nodes. — **Fig. 364**

Schematic illustration of matted metastatic regional lymph nodes. — **Fig. 365**

Schematic illustration of satellite(s) or in-transit metastasis with metastasis in regional lymph node. — **Fig. 366**

Schematic illustration of satellite(s) or in-transit metastasis with metastasis in regional lymph node(s). — **Fig. 367**

M – Distant Metastasis

M0	No distant metastasis
M1	Distant metastasis
	M1a	Skin, subcutaneous tissue or lymph node(s) beyond the regional lymph nodes (Figs. 324, 325, 326, 327)
	M1b	Lung
	M1c	Other sites, or any site with elevated serum lactate dehydrogenase (LDH)

pTNM Pathological Classification

pT – Primary Tumour

The pT classification of malignant melanoma considers the following histological criteria:

Tumour thickness (Breslow) according to the largest vertical diameter of the tumour in millimetre (Fig. 368)
Absence or presence of ulceration of the primary tumour

Schematic illustration of tumour thickness (Breslow) according to the largest vertical diameter of the tumour in millimetre. — **Fig. 368**

pTX	Primary tumour cannot be assessed*
pT0	No evidence of primary tumour
pTis	Melanoma in situ (Clark level I)

Note ^* pTX includes shave biopsies and curettage that do not fully assess the thickness of the primary.

pT1	Tumour 1 mm or less in thickness
	pT1a	Less than 0.8 mm thickness without ulceration (Fig. 369)
	pT1b	Less than 0.8 mm in thickness with ulceration or 0.8 mm or more but no more than 1 mm in thickness, with or without ulceration (Fig. 370)
pT2	Tumour more than 1 mm but not more than 2 mm in thickness (Fig. 371)
	pT2a	without ulceration
	pT2b	with ulceration
pT3	Tumour more than 2 mm but not more than 4 mm in thickness (Fig. 372)
	pT3a	without ulceration
	pT3b	with ulceration
pT4	Tumour more than 4 mm in thickness (Fig. 373)
	pT4a	without ulceration
	pT4b	with ulceration

Schematic illustration of Less than 0.8 mm thickness without ulceration. — **Fig. 369**

Schematic illustration of Less than 0.8 mm in thickness with ulceration or 0.8 mm or more but no more than 1 mm in thickness, with or without ulceration. — **Fig. 370**

Schematic illustration of tumour more than 1 mm but not more than 2 mm in thickness. — **Fig. 371**

Schematic illustration of tumour more than 2 mm but not more than 4 mm in thickness. — **Fig. 372**

Schematic illustration of tumour more than 4 mm in thickness. — **Fig. 373**

pN – Regional Lymph Nodes

The pN categories correspond to the N categories. (Figs. 357, 358, 359, 360, 361, 362, 364, 365, 366, 367).

pN0

Histological examination of a regional lymphadenectomy specimen will ordinarily include 6 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0. Classification based solely on sentinel node biopsy without subsequent axillary lymph node dissection is designated (sn) for sentinel node, e.g., pN1(sn). (See Introduction.)