Skin melanocytic tumor

• 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

• 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

• 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

• 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

Contributed by Robert E. LeBlanc, M.D.

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

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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Reference: Skin melanocytic tumor - Staging