Diagnosis

A normal freckle or mole is usually small and has an even colour and a smooth edge. A melanoma often has an irregular edge or surface.

It becomes more uneven in colour than other moles and eventually multiple colours develop (brown, black, blue, red, white or grey). A freckle or mole that itches or bleeds is sometimes (but not always) a melanoma. A freckle or mole that becomes larger or irregular in shape may be a melanoma. It is quite normal for new moles to appear and change during childhood. However, as we progress into adulthood new moles become is less common and changes in moles are more suspicious for melanoma. Melanoma can occur anywhere on the body but the great majority occur in sites that have received sun exposure.

Melanoma is diagnosed by physical examination and biopsy. Your doctor will first examine the suspicious spot or mole and other spots and moles and ask about your risk factors for melanoma.
If your doctor suspects that you have melanoma, they will suggest that you have a biopsy.

This is a quick and simple procedure. It may be done by your family doctor, or you may be referred to a dermatologist or surgeon. The doctor will give you a local anaesthetic and then use a surgical instrument to remove the spot and some surrounding tissue. You may have a stitch or stitches to help the wound to heal. Sometimes only a part of the lesion may be sampled. The tissue that is cut out will be sent to a laboratory to be examined under a microscope. It will probably take around a week for the results of your tests to be ready, and a follow-up appointment may be arranged for you. This waiting period can be an anxious time and it may help to talk things over with a close friend or relative. If the cells are found to be cancerous, a wider safety margin is removed around the site of the melanoma.

The diagnosis of melanoma prior to biopsy may be assisted by:

1. Dermoscopy is a method of examining skin lesions in greater detail to assess structures and pigment distribution beneath the surface of the skin. The dermoscope is a hand held device that has a magnifying lens and a light source. It is also possible to attach a dermoscope to a camera to obtain photographs of skin lesions which can be useful in detecting changes in lesions over time.
2. Confocal microscopy is an instrument can examine the cellular structure of a mole or melanoma while it is still on the skin and assess changes in the shape and arrangement of cells that may indicate melanoma. It is used at the Victorian Melanoma Service to diagnose difficult lesions and to assess the extent of some melanomas.
3. Total body photography is a set of photographs of the skin surface of the whole body are taken and then used as a reference to detect changes in lesions and new lesions both for checking at home and at later review appointments.
4. Sequential dermoscopy is a successive dermoscopic images of a lesion can be used to look for short term (3 months) or long term (12 months) change to help with the diagnosis of melanoma.

Measures to assess melanoma

Thickness

Tumour thickness is the most important measure of the risk associated with a primary melanoma. It is measures by the pathologist  when examining a melanoma biopsy. It is measured in millimetres from the skin surface to the deepest melanoma cell.

Level

Tumour level (or Clark level) is another measure of depth and assesses the tissue plane that the deepest part of the melanoma has reached. The levels go from I to V.

In situ and invasive

If your melanoma has been called in situ by the pathologist, abnormal cells are found only in the outer layer of skin cells (the epidermis) and have not penetrated deeper tissues (the dermis). In situ melanomas have no potential to spread or to be life threatening unless left in place and allowed to grow deeper.

Invasive melanomas have penetrated to the dermis. With greater depth of penetration of the dermis there is increasing risk of spread to other sites in the body via lymph or blood vessels.

Stages

• Stage I (1) - cancer is found in the epidermis and/or the upper part of the dermis but has not spread to nearby lymph nodes. The tumour is usually less than 1 mm thick. This stage also includes tumours up to 2 mm thick if they are not ulcerated.
• Stage II (2) - cancer has spread to the deeper part of the dermis but not into the tissue below the skin or into nearby lymph nodes. The tumour can be up to 4 mm thick.
• Stage III (3) - the tumour may be larger or smaller than 4 mm and/or may have spread to deeper layers of the skin. There may be additional tumour growths between the original tumour and the nearby lymph nodes; tumour cells may have spread to surrounding lymph nodes.
• Stage IV (4) - the tumour cells have spread to other organs or lymph nodes far away from the original tumour.

Your doctor will provide more information on the stage of your melanoma when discussing treatment.  

Sentinel lymph node biopsy

In patients with tumours thicker than 1.0 mm, a sentinel lymph node biopsy may be used to assess whether or not there has been spread to regional lymph nodes (the most common site of spread). This procedure involves the injection of radioactive dye in the region of the melanoma in order to identify the lymph node that is receiving the first lymphatic drainage from the site of the melanoma (the “sentinel” node).

Once identified, it is excised and examined for melanoma cells. Sentinel lymph node biopsy can be associated with certain, usually minor, complications and requires a general anaesthetic. The procedure provides more information about whether spread has occurred but does not improve the chance of cure. The risks and benefits are explained to patients and they are encouraged to make their own decision as to whether it is something they would like to procede with.

Other tests

If you have melanoma, your doctor may recommend other tests. This is generally if surgery is being planned or if there is evidence that the melanoma may have spread to other parts of the body. The tests include:

• Blood tests to check your general health
• Scans to see if the cancer has spread to other parts of your body. These may include ultrasound, a computerised tomography (CT) scan, a PET scan and/or a magnetic resonance imaging (MRI) scan. Not everybody needs these additional tests.