Stages of melanoma diagnosis

Staging melanoma is the process used to describe the extent of the disease. The doctor will take into account the tumor thickness and depth and whether the melanoma cells have spread, or metastasized, to the lymph nodes or other parts of the body. Staging helps the melanoma treatment team develop an appropriate treatment plan and determine the prognosis (outlook).

Melanoma Stage
Description
Treatment Option
0 The tumor is confined to epidermis and has not entered the dermis, a deeper layer of the skin. This stage of melanoma is also called melanoma in situ. The tumor and some surrounding tissue are removed surgically. Usually no further treatment is necessary; however, continued skin examination to evaluate for a new melanoma or other skin cancer will continue.
IA The tumor is less than 1 millimeter thick. The outer layer of skin does not look cracker or scraped (ulcerated). It has not spread to any lymph nodes or other organs. The tumor and some surrounding tissue are removed surgically. Usually no further treatment is necessary.   
IB The tumor is either less than 1 millimeter thick and ulcerated, or 1–2 millimeters thick and not ulcerated. It has not spread to any lymph nodes or other organs.  The tumor and some surrounding tissue are removed surgically. Usually no further treatment is necessary. 
IIA The tumor is either 1–2 millimeters thick and ulcerated, or 2–4 millimeters thick and not ulcerated. It has not spread to any lymph nodes or other organs.  The tumor and some surrounding tissue are removed surgically. Usually no further treatment is necessary. 
IIB The tumor is either 2–4 millimeters thick and ulcerated, or more than 4 millimeters thick and not ulcerated. It has not spread to any lymph nodes or other organs.  The tumor and some surrounding tissue are removed surgically. Additional treatment(s) may be recommended. 
IIC The tumor is more than 4 millimeters thick and is ulcerated. These are aggressive tumors that are more likely to spread.  The tumor and some surrounding tissue are removed surgically. Additional treatment(s) may be recommended. 

IIIA

IIIB

IIIC

The tumor may be of any thickness. It may or may not be ulcerated. The cancer cells have spread either to a few nearby lymph nodes, or to some tissue just outside the tumor but not to the lymph nodes. The tumor and lymph nodes that have cancer cells are removed surgically. Additional treatment(s) may be recommended. 
IV The cancer cells have spread to the lymph nodes, other organs in the body, or areas far from the original site of the tumor. This is called metastatic melanoma. The tumor and lymph nodes that have cancer cells are removed surgically. Additional treatment(s), like immunotherapytargeted therapy or clinical trials may be recommended.
 

 

Melanoma Diagnostics Indicators

To determine the specific stage of a melanoma, there are two common diagnostic indicators:

Breslow Thickness

Tumor thickness as defined by the Breslow's Depth of Invasion is the most important determinant of prognosis for melanomas. Increased tumor thickness is correlated with metastasis and poorer prognosis. The Breslow thickness is a better melanoma stage diagnostic indicator than the Clark’s level; it is a continuous variable and more accurate in its determinations.

The Breslow thickness is a measure (in millimeters) of the vertical depth of the tumor measured from the granular cell (very top) layer downward. An instrument called an Ocular Micrometer is used to measure the thickness of the excised tumor.

Tumor thickness remains the most powerful prognostic indicator that can be determined from evaluation of the primary melanoma itself. Because of the accuracy of determining outcomes, the Breslow thickness is commonly included in a melanoma diagnosis.

Tumors are classified into four categories based on the depth:

  • Less than or equal to 0.75 mm (equivalent to Clark's Level II)
  • 0.76-1.5 mm (equivalent to Clark's Level III)
  • 1.51-4 mm (equivalent to Clark's Level IV)
  • Greater than or equal to 4 mm (equivalent to Clark's Level V)

Breslow Thickness and Survival Rate:

  • <1mm: 5-year survival is 95-100%
  • 1-2mm: 5-year survival is 80-96%
  • 2.1-4mm: 5-year survival is 60-75%
  • >4mm: 5-year survival is 37-50% 

Clark’s Level

The Clark’s level is commonly misunderstood as the melanoma stage diagnosis. The Clark’s level only refers to how deep the tumor has penetrated into the skin. Research has shown that the Clark’s level diagnosis is not a great predictor of outcome.    

Clark's Level I - Confined to epidermis – also called “in situ” melanoma 

Clark's Level II - Invasion of the papillary dermis (upper) 

Clark's Level III - Filling of the papillary dermis (lower) 

Clark's Level IV - Extending into the reticular dermis 

Clark's Level V - Invasion of the subcutaneous tissue