Skin melanocytic tumor
Staging
Pathologic TNM staging of Melanoma of the skin, AJCC 8th edition


Topic Completed: 9 April 2019

Revised: 16 May 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Staging melanomas [title] skin AND (free full text)


Robert E. LeBlanc, M.D.
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Cite this page: LeBlanc RE. Pathologic TNM staging of Melanoma of the skin, AJCC 8th edition. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumormelanocyticmelanomastaging.html. Accessed September 22nd, 2019.
Definition / general
  • All cutaneous melanomas are covered by this staging system
  • These topics are not covered:
    • Melanoma of the conjunctiva
    • Melanoma of the uvea
    • Mucosal melanoma of the head and neck
    • Mucosal melanoma of the urethra, vagina, rectum and anus
    • Merkel cell carcinoma
    • Squamous cell carcinoma
Essential features
  • AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the AJCC, 8th Edition, 2018 is mandatory
ICD coding
  • ICD-10: C43 - Malignant melanoma of skin
Diagrams / tables

Images hosted on other servers:

Clark levels

Primary tumor (pT)
  • pTX: thickness cannot be assessed (e.g. curettage specimen)
  • pT0: no evidence of primary tumor (unidentified or completely regressed primary)
  • pTis: melanoma in situ
  • pT1a: < 0.8 mm thickness without ulceration
  • pT1b: < 0.8 mm thickness with ulceration or 0.8 - 1.0 mm thickness with or without ulceration
  • pT2a: > 1.0 - 2.0 mm thickness without ulceration
  • pT2b: > 1.0 - 2.0 mm thickness with ulceration
  • pT3a: > 2.0 - 4.0 mm thickness without ulceration
  • pT3b: > 2.0 - 4.0 mm thickness with ulceration
  • pT4a: > 4.0 mm thickness without ulceration
  • pT4b: > 4.0 mm thickness with ulceration

Notes:
  • Breslow depth: measure from the surface of the epidermal granular layer to the point of maximum tumor thickness at a right angle to adjacent epidermis
    • Measured with a calibrated ocular micrometer
    • Measurement is rounded to the nearest 0.1 mm
    • Report as "at least _ mm" if the maximum tumor thickness cannot be determined, most commonly when invasive melanoma is present at the edge of a shave biopsy
  • Ulceration: full thickness epidermal defect including absence of stratum corneum and basement membrane, fibrin deposition and neutrophils and thinning, effacement or reactive hyperplasia of the adjacent epidermis in the absence of a trauma or recent surgical procedure
Regional lymph nodes (pN)
  • pNX: cannot be assessed (staging procedure not performed or previously removed)
  • pN0: no regional metastasis
  • pN1a: 1 nodal metastasis, clinically occult (no in transit / satellite / microsatellite metastasis)
  • pN1b: 1 nodal metastasis, clinically detected (no in transit / satellite / microsatellite metastasis)
  • pN1c: negative for nodal metastasis (positive in transit / satellite / microsatellite metastasis)
  • pN2a: 2 to 3 nodal metastases, clinically occult (no in transit / satellite / microsatellite metastasis)
  • pN2b: 2 to 3 nodal metastases, clinically detected (no in transit / satellite / microsatellite metastasis)
  • pN2c: 1 nodal metastasis, clinically occult or detected (positive for in transit / satellite / microsatellite metastasis)
  • pN3a: 4 or more nodal metastasis, clinically occult (no in transit / satellite / microsatellite metastasis)
  • pN3b: 4 or more nodal metastasis, clinically detected (no in transit / satellite / microsatellite metastasis)
  • pN3c: 2 or more nodal metastasis (positive for in transit / satellite / microsatellite metastasis)

Notes:
  • Regional lymph nodes / sentinel lymph nodes: sentinel node(s) receive direct lymphatic drainage from the primary tumor site as determined by lymphatic mapping
  • Clinically occult: nodal metastasis detectable only by microscopic evaluation
  • Clinically detected: lymph node enlarged or abnormal by physical or radiologic examination
  • Microsatellite metastasis: microscopic (no size cutoff) cutaneous or subcutaneous metastasis adjacent or deep to the primary melanoma; microsatellite cells are not contiguous with those of the primary melanoma (serial step level sections through the tissue block are often necessary for confirmation) and there is no intervening dermal inflammation, fibrosis or scarring
  • Satellite metastasis: intralymphatic metastasis within 2 cm of the primary melanoma
  • In transit metastasis: intralymphatic metastasis > 2 cm from primary melanoma but not beyond the regional lymph nodes
Distant metastasis (pM)
  • pM0: no evidence of distant metastasis
  • pM1a(0): distant metastasis to skin, soft tissue (including muscle) or nonregional lymph node; LDH level not elevated
  • pM1a(1): distant metastasis to skin, soft tissue (including muscle) or nonregional lymph node; LDH level elevated
  • pM1b(0): distant metastasis to lung; LDH level not elevated
  • pM1b(1): distant metastasis to lung; LDH level elevated
  • pM1c(0): distant metastasis to non CNS viscera; LDH level not elevated
  • pM1c(1): distant metastasis to non CNS viscera; LDH level elevated
  • pM1d(0): distant metastasis to CNS; LDH level not elevated
  • pM1d(1): distant metastasis to CNS; LDH level elevated
Prefixes
  • y: post therapy or post neoadjuvant radiotherapy or chemotherapy
  • r: recurrent tumor
  • a: autopsy classification
AJCC clinical prognostic stage groups (cTNM)
  • Completed following the biopsy
  • Incorporates histologic information from the biopsy with clinical (radiologic) staging data

    Stage group 0: Tis N0 M0
    Stage group IA: T1a N0 M0
    Stage group IB: T1b - T2a N0 M0
    Stage group IIA: T2b - T3a N0 M0
    Stage group IIB: T3b - T4a N0 M0
    Stage group III: Any T ≥ N1 M0
    Stage group IV: Any T Any N M1
AJCC pathological prognostic stage groups (pTNM)
  • Generally reserved for patients with disease beyond cTNM stage IA
  • Completed following the wide surgical excision and staging biopsies (e.g. sentinel node)
  • Incorporates histologic information from the excision and staging specimens

    Stage group 0: Tis N0 M0
    Stage group IA: T1a - T1b N0 M0
    Stage group IB: T2a N0 M0
    Stage group IIA: T2b - T3a N0 M0
    Stage group IIB: T3b - T4a N0 M0
    Stage group IIC: T4b N0 M0
    Stage group IIIA: T1a - T2a N1a - N2a M0
    Stage group IIIB: T0 N1b - N1c M0
    T1a - T2a N1b - N2b M0
    T2b - T3a N1a - N2b M0
    Stage group IIIC: T0 N2b - N3c M0
    T1a - T3a N2c - N3c M0
    T3b - T4a N1a - N3c M0
    T4b N1a - N2c M0
    Stage group IIID: T4b N3a - N3c M0
    Stage group IV: Any T Any N M1
Registry data collection variables
  • Breslow tumor thickness (xx.x mm)
  • Ulceration (yes or no)
  • Mitotic rate (whole number per square mm2)
  • Microsatellites, not clinically detected (yes or no)
  • Tumor infiltrating lymphocytes (absent, non brisk or brisk)
  • Clark level of invasion (1 - 5)
  • Regression (yes or no)
  • Neurotropism (present or absent)
  • Lymphovascular invasion (present or absent)
  • In transit / satellite metastasis (in transit, satellite or both)
  • Regional lymph node clinical or radiological detection (yes or no)
  • Microscopic confirmation of metastasis in clinical or radiologically detected node (yes or no)
  • Sentinel lymph node biopsy performed (yes or no)
  • Number of nodes examined from sentinel node procedure (whole number)
  • Number of tumor involved nodes from sentinel node procedure (whole number)
  • Sentinel node tumor burden (cross section diameter of largest discrete deposit in mm)
  • Extranodal extension in in any lymph node or clinically detected (present or absent)
  • Completion or therapeutic lymph node dissection performed (yes or no)
  • Number of lymph nodes examined from completion or therapeutic dissection (whole number)
  • Number involved with tumor from completion or therapeutic dissection (whole number)
  • Matted nodes (yes or no)
  • Distant metastasis to skin, soft tissue or distant (nonregional) node (yes or no)
  • Distant metastasis to lung (yes or no)
  • Distant metastasis to non CNS viscera (yes or no)
  • Distant metastasis to CNS (yes or no)
  • Serum LDH level and serum LDH level upper limit of normal from laboratory reference range

Notes:
  • Tumor infiltrating lymphocytes: considered brisk when the inflammation diffusely infiltrates the tumor or is present around the entire base of the tumor
  • Clark level of invasion: superseded by Breslow depth but often still reported
    • Level 1: melanoma in situ
    • Level 2: invasion of the papillary dermis
    • Level 3: filling but confined to the papillary dermis
    • Level 4: invasion of the reticular dermis
    • Level 5: invasion of subcutaneous fat
  • Regression: replacement of melanoma cells by lymphocytic inflammation; this commonly has the appearance of an attenuated epidermis with rete effacement, mild dermal fibrosis and vascular ectasia with perivascular lymphocytes and melanophages
Histologic grade (G)
  • Not used in melanoma staging
Histopathologic type
  • Modified World Health Organization classification (Elder: WHO Classification of Skin Tumours (Medicine), 4th Edition, 2018)
    • Superficial spreading melanoma
    • Acral lentiginous melanoma
    • Lentigo malignant melanoma
    • Desmoplastic melanoma
    • Nodular melanoma
    • Melanoma arising from blue nevus
    • Melanoma arising in a giant congenital nevus
    • Melanoma of childhood
    • Nevoid melanoma
    • Melanoma, not otherwise classified
    • Other histologic type not listed
Microscopic (histologic) images

Contributed by Robert E. LeBlanc, M.D.
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Breslow depth

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Nodal nevus

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Nodal metastasis


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Regression

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Microsatellite

Board review question #1
    Which of the following melanomas is associated with the worst prognosis?

  1. Depth 1.1 mm, nonulcerated, three occult SLN metastases
  2. Depth 1.9 mm, nonulcerated, one occult SLN metastasis, one nonregional lymph node metastasis
  3. Depth 2.4 mm, nonulcerated, SLN negative for metastasis, one satellite metastasis
  4. Depth 4.5 mm, ulcerated, SLN negative for metastasis
Board review answer #1
B. Melanomas with nonregional lymph node metastases are categorized as pM1a. The presence of distant metastases, including nonregional lymph node involvement, places a melanoma in stage IV irrespective of the other tumor attributes. In contrast, sentinel node metastases, in transit metastases, satellite metastases and microsatellites are not considered distant metastases. These findings affect the pN category but not pM.

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