Diagnosis & Staging

Melanoma is often but not always diagnosed after a suspicious mole is noticed by the patient, a relative or a doctor. This can happen during a screening or routine skin examination, especially for people with fair skin, red hair, a tendency to burn in the sun and multiple naevi. 

The diagnosis of melanoma is based on the following examinations: 

Clinical examination* 

The doctor asks the patient questions, especially regarding possible risk factors, and about the evolution of the suspicious mole(s). Examination of the suspicious mole(s) and of the rest of the skin is also done. As mentioned above, a suspicious mole presents the ‘ABCDE’ characteristics: 

    • Asymmetry in its shape 
    • Border irregularity or a border which is ill‐defined 
    • Colour varying from one area to another 
    • Diameter
    • Evolution over time

Not all melanomas present the all characteristics altogether. In addition, the doctor also feels the lymph nodes in the groin, armpit, neck, etc. depending on the location of the suspicious mole(s). 


This consists of using a small device called dermoscope or dermatoscope which illuminate and magnify the spots on the skin for a more precise examination. Even if examination with a dermoscope is not always necessary, it enhances the accuracy of diagnosis when performed by an experienced doctor trained to use this technique. 

Histopathological examination after removal of the whole mole

A histopathological examination is the laboratory examination of the tumor cells by dissecting the tumor. This will confirm the diagnosis of melanoma. The tumor has to be cut out completely and then sent to the laboratory. This is called a skin biopsy and is done manually by the doctor. First, a local anaesthetic is injected into the area that is going to be removed. Then, the suspicious mole is removed ensuring a certain margin of normal tissue around and under the tumor is also removed. It is very important that both removal of the mole and laboratory examination are performed by professionals with experience in the treatment of melanoma.

A very useful webinar to help to understand your Melanoma Pathology can be found here:




Doctors use staging to assess the extent of the cancer and the prognosis of the patient. The TNM staging system is commonly used. The combination of size of the tumor and invasion of nearby tissue (T), involvement of lymph nodes (N) and metastasis, spread of the cancer to other organs of the body (M), will classify the cancer into one of the following stages as presented in the table below. 

The stage is fundamental for the decision on treatment. The more advanced the stage, the worse the prognosis. Staging is performed by combining results of clinical examination, histopathological examination and sometimes radiological examination which is performed if clinical or histopathological examinations indicate that the cancer cells may have spread to other places than the initial skin tumor. Staging may be done a second time after the results of the histopathological examination of the lymph nodes removed by surgery. 

The table below presents the different stages for melanoma. The definitions are somewhat technical so it is recommended to ask doctors for more detailed explanations.

Stage Definition
Stage 0 The tumor is limited to the epidermis and has not spread to the dermis (see picture used in the definition). In addition, no tumor cell is found in the lymph nodes. Stage 0 melanoma is also called in situ melanoma.
Stage I

The thickness of the tumor is:

  • Either less than 2 mm in diameter with no ulceration 
  • Or less than 1 mm in diameter but has ulceration* or has invaded the lower layer of the dermis, called reticular dermis or the subcutaneous fat 

In addition, no tumor cell is found in the lymph nodes. 

Stage I is divided into stages IA and IB according to the combination of thickness, depth of invasion in the dermis and ulceration.

Stage II

The thickness of the tumor is:

  • Either more than 1 mm in diameter with ulceration
  • Or more than 2 mm in diameter (with or without ulceration*)

In addition, no tumor cell is found in the lymph nodes.

Stage II is divided into stages IIA, IIB and IIC according to the combination of thickness and presence or absence of ulceration.

Stage III

Regardless of tumor thickness and presence of ulceration, the tumor has spread to the lymph nodes (lymph node metastasis) or groups of tumor cells are found less than 2 cm away from the initial tumor (satellite metastasis) or on the way from the initial tumor to the lymph nodes (in‐transit metastasis). Lymph node, satellite and in‐transit metastasis are called loco‐regional metastasis.

Stage III is divided into stage IIIA, IIIB and IIIC according to the location, the number and the extent of loco‐regional metastases where tumor cells have spread.

Stage IV

The tumor has spread:

  • Either beyond the regional lymph nodes to the skin or other lymph nodes
  • Or to other organs such as the liver, lungs or brain


Source: based on Melanoma: a guide for patients ‐ Information based on ESMO Clinical Practice Guidelines ‐ v.2011.2