How is malignant melanoma diagnosed?

Anybody who detects a mole that looks different from before should see their GP (general practitioner, primary care physician) immediately. The doctor will look at the patient's skin and determine whether further assessment is required. In the UK it is common for a GP to take a digital photograph of an unusual-looking mole and to email it to a skin specialist (dermatologist).

If the doctor suspects there may be something unusual he will usually refer the patient to a dermatologist. The dermatologist will most likely perform a biopsy - the mole is removed and examined under a microscope to find out whether it has cancerous cells in it.

If the biopsy indicates there are cancerous cells, the doctor may carry out further biopsies on the lymph nodes nearest to where the mole was.

If the doctor wants to find out whether the cancer might have spread into other parts of the body, he/she may carry out:

• Blood tests
• A chest X-ray
• An MRI (magnetic resonance imaging) scan
• A CT (computerized tomography) scan

A team of researchers from the University of California, San Francisco, has developed a technique to distinguish benign moles from malignant melanomas by measuring differences in levels of genetic markers.