Staging a melanoma means that the doctor will try to determine the extent of the spread of the disease and whether or not it has moved from the original position on the skin to the lymph nodes or through the bloodstream into other parts of the body.

The first step in staging is to measure how deeply into the skin the cancer cells have grown. The pathologist does this when they receive the biopsy from the surgeon. The depth of the melanoma is important because the deeper the cancer cells have grown into the skin, the more likely it is the cancer will come back or spread to the lymph nodes or elsewhere in the body.

If the cells have not penetrated very deeply into the skin, the removal of the melanoma by the biopsy may be all that is needed and you will not need any further treatment. However, when the tumour has penetrated further into the skin, more tissue may need to be removed from around the melanoma.

Patients with melanoma are staged with at least two staging systems to determine the potential risk or actual extent of tumour spread (metastasis).

• Microstaging
• Clinical Staging

When appropriate staging radiological examination and serum biochemistry may be required to maximize the accuracy of staging.

Microstaging

This is performed by the pathologist examining the biopsy specimen under the microscope. The type of cell which is abnormally proliferating determines the type of skin tumor.(ie melanomas are comprised of melanocytes which are growing in an unregulated manner). The vertical depth (Breslow thickness) of the tumour gives important information about the potential of the tumour to spread (metastasise) to other parts of the body, especially the related lymph node groups.

There are many features that need to be assessed by the pathologist.
The most important of these include:

Breslow thickness
Clark level
Presence or absence of ulceration
Mitotic rate
Evidence of regression
Invasion of blood vessels, lymphatics or nerves
Immune cell response
Excision margins

Clark Level
	Breslow Thickness (mm)

 

The melanoma microstaging systems of Clark & Breslow.

Clinical Staging

Melanoma patients are physically examined to identify any other lesions on their skin which may be of concern. The lymph node groups that relate to the site of the primary melanoma are carefully examined to determine any evidence of spread (lymph node metastasis). Patients with thin melanomas are likely to be node negative (N0), whilst those with thick primary tumours may be clinically node positive (N+). There can be a variety of reasons for a lymph node to become enlarged. If there is any doubt a fine needle aspiration biopsy (FNAB) can be performed. A regular needle attached to an empty syringe is passed into the suspicious lymph node and some cells are removed. The material is then examined under a microscope by the pathologist and even a very small number of malignant cells can be identified.

Patients with suspicious findings in the histopathology microstaging or after examination by their doctor may warrant further investigation. 

Staging after Investigation

When indicated, melanoma patients may require specific investigations. These may include CT, NMR, and PET scans, each involving the patient resting in a comfortable horizontal slide which is passed through an arched opening in a scanner. These examinations are not uncomfortable. They often involve a simple injection of contrast or imaging agent through a butterfly needle on the back of the hand.

Revised AJCC Staging System

(AJCC: American Joint Committee on Cancer)

Stage I
1A Tumour	<1.00 mm without ulceration; no lymph node involvement, no distant metastases.
1B Tumour	<1.00 mm with ulceration or Clark level IV or V tumour 1.01 – 2.0 mm without ulceration; no lymph node involvement; no distant metastases.
Stage II
11A Tumour	1.01 – 2.0 mm with ulceration; tumour 2.01 – 4.0 mm without ulceration; no lymph node involvement; no distant metastases.
11B Tumour	2.01 – 4 mm with ulceration.
11B Tumour	> 4.0 mm without ulceration; no lymph node involvement; no distant metastases.
11C Tumour	> 4.0 mm with ulceration; no nodal involvement; no distant metastases.
Stage III
111A	Tumour of any thickness without ulceration with 1 positive lymph node and micrometastasis or macrometastasis.
111B	Tumour of any thickness without ulceration with 2-3 positive lymph nodes and micrometastasis or macrometastasis.
111C	Tumour of any thickness and macrometastasis OR in-transit met(s)/satellite(s) without metastatic lymph nodes, OR 4 or more metastatic lymph nodes, matted nodes or combinations of in-transit met(s)/satellite(s), OR ulcerated melanoma and metastatic lymph node(s).
Stage IV
1V	Tumour of any thickness with any nodes and any metastases

Mets = metastases

Ulceration = the absence of an intact epidermis overlying a portion of the primary melanoma based on pathologic microscopic observation of the histologic sections.

Sentinel Node Staging

Melanoma is a skin cancer which can metastasise, that is, spread to the lymph nodes or glands. Initially these metastases are only visible under a microscope. To determine whether this has occurred the node(s) which is most at risk of being involved, the sentinel node, needs to be removed and examined. This procedure is called a Sentinel Node Biopsy and has three stages

• Lymphoscintigram
  An injection of radio-isotope and lymphatic mapping prior to surgery
• Selective Node Biopsy
• Assessment by Pathologist