Baffled is a good word for it. There is actually a cancer known as 'cancer of unknown primary' where they sometimes never figure out the type of cancer or where it originated. We are hoping we won't be in that category forever.
My husband has a tumor in his lung. It is cancer. He also has cancer in one lymph node (the subcarinal lymph node). Both cancers come back as the same material/cancer. However, the pathology on the cancer can't be identified as a specific cancer. He had a lung biopsy and three biopsies of the lymph nodes via different means. All the tissue samples match from all the biopsies but it isn't identifiable as a lung cancer completely or any other type of cancer. The cancer has elements of several types of cancer but none stands out. It is truly odd and it's been looked at by multiple pathology groups, including the Mayo Clinic. It's been on a trip around the country. They simply don't know what type of cancer it is ....yet.........
I am a breast cancer survivor so we know the cancer ropes all too well but this has been an eye opener (in a bad way). We have two oncology groups working with us here in Colorado. One is the prominent leader in cancer here at the University of Colorado. All the doctors and pathologists agree that all they can do is wait, watch and see where the primary cancer shows up, whether that's in the lung ultimately (the only place their is a tumor) or somewhere else. Sometimes they never find the primary cancer. it's rare but it happens. Who knew........