Skip to content
My WebMD Sign In, Sign Up

Melanoma/Skin Cancer Health Center

Font Size

Melanoma Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Stage Information for Melanoma

Agreement between pathologists in the histologic diagnosis of melanomas and benign pigmented lesions has been studied and found to be considerably variable. One such study found that there was discordance on the diagnosis of melanoma versus benign lesions in 37 of 140 cases examined by a panel of experienced dermatopathologists.[1] For the histologic classification of cutaneous melanoma, the highest concordance was attained for Breslow thickness and presence of ulceration, while the agreement was poor for other histologic features such as Clark level of invasion, presence of regression, and lymphocytic infiltration. In another study, 38% of cases examined by a panel of expert pathologists had two or more discordant interpretations. These studies convincingly show that distinguishing between benign pigmented lesions and early melanoma can be difficult, and even experienced dermatopathologists can have differing opinions. To reduce the possibility of misdiagnosis for an individual patient, a second review by an independent qualified pathologist should be considered.[2]

The microstage of malignant melanoma is determined on histologic examination by the vertical thickness of the lesion in millimeters (Breslow classification) and/or the anatomic level of local invasion (Clark classification). The Breslow thickness is more reproducible and more accurately predicts subsequent behavior of malignant melanoma in lesions larger than 1.5 mm in thickness and should always be reported. Accurate microstaging of the primary tumor requires careful histologic evaluation of the entire specimen by an experienced pathologist. Estimates of prognosis should be modified by sex and anatomic site as well as by clinical and histologic evaluation.

Clark Classification (Level of Invasion)

  • Level I: Lesions involving only the epidermis (in situ melanoma); not an invasive lesion.
  • Level II: Invasion of the papillary dermis but does not reach the papillary-reticular dermal interface.
  • Level III: Invasion fills and expands the papillary dermis but does not penetrate the reticular dermis.
  • Level IV: Invasion into the reticular dermis but not into the subcutaneous tissue.
  • Level V: Invasion through the reticular dermis into the subcutaneous tissue.

Definitions of TNM

The American Joint Committee on Cancer (AJCC) has designated staging by TNM classification to define melanoma.[3]

Table 1. Primary Tumor (T)a

a Reprinted with permission from AJCC: Melanoma of the skin. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 325-44.
TXPrimary tumor cannot be assessed (e.g., curettaged or severely regressed melanoma).
T0No evidence of primary tumor.
TisMelanomain situ.
T1Melanomas ≤1.0 mm in thickness.
T2Melanomas 1.01–2.0 mm.
T3Melanomas 2.01–4.0 mm.
T4Melanomas >4.0 mm.
Note: a and b subcategories of T are assigned based on ulceration and number of mitoses per mm2 as shown below:
T classificationThickness (mm)Ulceration Status/Mitoses
T1≤1.0a: w/o ulceration and mitosis <1/mm2.
b: with ulceration or mitoses ≥1/mm2.
T21.01–2.0a: w/o ulceration.
b: with ulceration.
T32.01–4.0a: w/o ulceration.
b: with ulceration.
T4>4.0a: w/o ulceration.
b: with ulceration.
1|2|3

WebMD Public Information from the National Cancer Institute

Last Updated: February 25, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
Next Article:

Today on WebMD

Malignant melanoma
About 40-50 percent of those who live to be 65 may get it. Here’s how to spot early.
Woman checking out tan lines
There’s a dark side to that strive for beauty. See them here.
 
sauteed cherry tomatoes
Fight cancer one plate at a time.
Lung cancer xray
See it in pictures, plus read the facts.
 
12 Ways to Protect Your Skin from Melanoma
ARTICLE
precancerous lesions slideshow
SLIDESHOW
 
Do You Know Your Melanoma ABCs
VIDEO
15 Cancer Symptoms Men Ignore
ARTICLE
 
screening tests for men
SLIDESHOW
Vitamin D
SLIDESHOW
 
Is That Mole Skin Cancer
VIDEO
Brilliant sun rays
Quiz
 

WebMD Special Sections