If your doctor suspects that a mole or growth on your skin is melanoma, he or she will need to do an excisional biopsy. This is the only way to make a definite diagnosis of melanoma.
The doctor (a dermatologist or surgeon) tries to remove all of the suspicious-looking growth. If the growth is too large to be removed easily, the doctor removes a part of it. This can usually be done in the doctor's office, using a local anesthetic. A pathologist then examines what was removed under a microscope to check for cancer cells.