How is lentigo maligna melanoma staged?

Updated: Dec 19, 2019
  • Author: Winston W Tan, MD, FACP; Chief Editor: William D James, MD  more...
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Answer

Answer

Lentigo maligna is melanoma in situ; lentigo maligna melanoma is melanoma.

The American Joint Committee on Cancer (AJCC) Tumor, Node, Metastases (TNM) staging for melanoma uses tumor size, rather than invasion, and ulceration and number of mitoses per mm2 to stage the tumor. [14]

Tumor staging is as follows. For the stages below, the addition of “a” indicates without ulceration and of “b” indicates with ulceration, except for “T1a,” which indicates without ulceration and mitosis less than 1/mm2 and “T1b,” which indicates with ulceration or mitoses 1 or more per mm [210] :

  • Tx – Primary tumor cannot be assessed (eg, diagnosis by curettage)
  • T0 – No evidence of primary tumor (eg, unknown primary or completely regressed melanoma)
  • Tis – Melanoma in situ
  • T1 – 1 mm or less in thickness; T1a, < 0.8 mm without ulceration; T1b, < 0.8 mm with ulceration or 0.8-1.0 mm with or without ulceration
  • T2 – > 1.0-2.0 mm; T2a, > 1.0-2.0 mm without ulceration; T2b, > 1.0-2.0 mm with ulceration
  • T3 – > 2.0-4.0 mm; T3a, > 2.0-4 mm without ulceration; T3b, >2.0-4.0 mm with ulceration
  • T4 –  > 4.0 mm; T4a, > 4.0 mm without ulceration; T4b, >4.0 mm with ulceration

Regional nodal staging is as follows. For the stages below, the addition of “a” indicates micrometastasis clinically occult (ie, detected by sentinel lymph node biopsy [SLNB]); of “b” indicates macrometastasis clinically apparent; and of “c” indicates in transit, satellite, or microsatellite metastasis without metastatic nodes [14] :

  • Nx – Nodes not assessed (eg, SLNB not performed, regional nodes previously removed for another reason); the exception is that a pT1 cM0 melanoma with no clinically detected regional metastases is designated as cN0 instead of pNX
  • N0 – No regional metastases detected
  • N1 –  One tumor-involved node (N1a, N1b); or in-transit, satellite, and/or microsatellite metastases with no tumor-involved nodes (N1c)  
  • N2 – Two or three tumor-involved nodes; clinically occult (N2a) or at least one clinically detected (N2b); or one clinically occult or clinically detected with in-transit, satellite, and/or microsatellite metastases present
  • N3 – Four or more metastatic nodes; in transit, satellite, or microsatellite metastasis with two or more tumor-involved nodes; or any number of matted nodes without or with in transit, satellite, or microsatellite metastases
  • N3a  –  Four or more clinically occult nodes
  • N3b – Four or more tumor-involved nodes, at least one of them clinically detected, or presence of any number of matted nodes
  • N3 c – Two or more clinically occult or clinically detected tumor-involved nodes, or presence of any number of matted nodes, with in transit, satellite, or microsatellite metastases present

M indicates distant metastasis and is staged incorporating serum lactate dehydrogenase (LDH) levels as follows [14] :

  • M0 – No detectable evidence of distant metastases
  • M1a – Metastases to skin, soft tissue (including muscle), or distant lymph nodes; M1a(0), LDH level not elevated; M1a(1), LDH level elevated 
  • M1b – Metastases to lung, with or without M1a sites of disease; M1b(0), LDH level not elevated; M1b(1), LDH level elevated
  • M1c – Metastases to visceral sites other than the central nervous system (CNS), with or without M1a or M1b sites of disease; M1c(0), LDH level not elevated; M1c(1), LDH level elevated
  • M1d – Metastasis to CNS with or without M1a, M1b, or M1c sites of disease; M1d(0), LDH level normal; M1d(1), LDH level elevated

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