What could spots on the liver be?

My best friend is distraught because her sister had stage 4 melanoma last year. She was treated and things were going well. Well she found a cyst on her wrist and went to get checked again. Due to her history the doctor ordered a CT scan. In the scan they found spots on her liver and now are moving to an MRI. The MRI will be preformed tonight. My friend is worried it is liver cancer. That the melanoma spread. Could it be nothing? What other things will show up as spots on someones liver other than cancer? Just a little more information....The skin cancer was thought to be caused by excessive tanning. Her sister tanned all the time when she was younger and there is no family history of cancer.