I was diagnosed with melanoma in 2011 when I was 28.
I had the suspicious mole cut off my back by my GP. It was sent away and came back as melanoma. I then was booked into the Alfred hospital and within 2 weeks I saw a specialist and went under a general anesthesia to have the area around it removed. I now have a 10cm scar on my back and I've been healthy since. My melanoma was only 0.75mm thick but even at 1mm it can get into your blood stream and spread.
The most important things he needs to know are the thickness and the stage which will tell him if its aggressive or slow growing and how deep it is to know if it's close to spreading. It usually spreads to the closest lymph node first so he should have his lymph nodes checked (in the groin, under arms, neck etc).
Prognosis is good if its caught early so I wouldn't go into an immediate panic. Just because the docs want to get onto it right away doesn't necessarily mean its really bad news. All melanomas are taken very seriously in Australia and docs like to fast track the treatment.