Diagnosis

How is melanoma diagnosed?

If you notice a change on your skin, such as new spot or an existing spot, freckle or mole that has changed in colour, shape or size, you should see your doctor. Melanoma is diagnosed by physical examination and biopsy. A biopsy is a quick and simple procedure where part or all of the spot is removed and sent to a laboratory. The biopsy may be done by your GP or you can be referred to a dermatologist or surgeon.

Biopsy

This is the first diagnostic procedure performed if melanoma is suspected. Depending on the results it may be the only procedure needed. Your Doctor will remove the suspicious skin lesion and send this away for testing by a pathologist. (See What Happens in the Laboratory)

The results of this test will tell your Doctor a great deal in regards to your diagnosis, including:

• If melanoma is present
• The thickness of the melanoma (using the Breslow Thickness scale )
• Invasion of blood vessels, lymphatics or nerves
• Excision margins
  

To perform the biopsy your doctor will wipe the site with rubbing alcohol and outline the suspicious lesion with a coloured marker. Local anaesthetic is then injected in and around the area to make sure you do not feel any discomfort when the biopsy is performed. Your Doctor will then remove the suspicious skin lesion and put this in a small pot to be sent away for testing. Your Doctor will put stitches in place so that the wound can heal. Depending on your age, medical history and the site from where the biopsy is taken, you may need to take a course of antibiotics as a preventative to ensure you do not get an infection. The biopsy site will then be covered with a sterile dressing. This is usually kept in place (and kept dry) for 2 – 3 days after which time you can remove the dressing yourself. Your Doctor may use dissolving stitches or you may need to come back to have the stitches removed. All of this will be explained to you before the biopsy takes place.

Read more about biopsies:  Taking Biopsies of Melanoma

If your Doctor suspects that you may have metastatic melanoma (melanoma which has spread to places within your body) your Doctor may suggest other diagnostic procedures. See Further Investigations.

What happens in the laboratory? Dermatopathology

Dermatopathology is the specialty of pathology in the skin. This is where the diagnosis of melanoma is made under the microscope, and is a critical component in the overall management of melanoma. The specimen that is cut out of the skin is processed in the laboratory onto small glass slides which are each careful examined for the signs of melanoma.

Once the diagnosis of melanoma is established, the specimens are then graded according to established melanoma risk factors to try and predict how badly the melanoma may behave. This importantly includes measuring the thickness of the melanoma which most accurately predicts risk. The edges of the specimen are also assessed to ensure that the melanoma has been completely removed.

Just as there has been improvement in the way melanoma is detected, dermatopathology has evolved with the development of new techniques to improve the accuracy of the diagnosis. The incidence of melanoma has been reported in some studies to have doubled over recent decades. This can be attributed to both an increase in the detection of melanoma, but also to an increase in the diagnosis of melanoma under the microscope. Over time we have learnt that some of the lesions previously thought to be benign have proven to behave like a melanoma. These are therefore now also diagnosed as melanoma.

Much goes on at the interface with the doctor in the clinic, but there is a lot of careful medicine going on behind the scenes in the laboratory. While it is hoped that improvements can be made soon in the treatment of melanoma, there have been many advances in the ability to diagnose it under the microscope.