The first step of diagnosing stage 0 melanoma usually involves a visual inspection. If you notice an unusual growth or change in a mole on your own skin, see a doctor right away. The doctor will visually examine the mole or growth. If the doctor suspects melanoma, a biopsy will be performed, which involves removing the growth and analyzing it under a microscope. Since stage 0 melanoma often involves a small mole or growth, the doctor will likely remove the whole growth for the biopsy.