Sorry to hear about your Mother. As Christine states, a biopsy is required to determine if the cells are cancerous. With the PET staging can be done.

Given the situation you offered, speak with your Mom and ask her to be added to the list for receiving all reports and access to her doctors. That way at least you can get information directly and also ask specific questions particularly as if this cancer and at her age there will be more difficult decisions ahead.

There is a lot of information here so start reading up and feel free to post as you move along.