If your doctor thinks a mole may be melanoma, he or she will do a biopsy of the skin or refer you to a specialist for the procedure.
Before the biopsy, your doctor will check for enlarged lymph nodes close to the mole. If you have a melanoma, enlarged lymph nodes can mean that the cancer has spread. After a skin biopsy, nearby lymph nodes can swell because the skin incision is healing.
In a biopsy, a doctor removes a piece of tissue and examines it in a laboratory. Based on this report, your doctor can then determine the thickness of the melanoma and how deep the cancer has grown below the skin's surface. That's the most important factor in predicting whether it can be cured.
Melanomas deeper than 1 millimeter are more likely to have spread to other parts of the body. Your doctor may suggest additional tests including:
A chest x-ray
Computed tomography (CT)scans
If the cancer is advanced, the biopsy sample of your melanoma may be tested to see if it has one of the gene mutations common in melanoma. Some melanoma treatments have been designed to attack specific genetic subtypes of this cancer.