That's pretty much the same thing my DR. said. I have multiple lymph nodes that are enlarged and have uptake in the PET Scan. When they did a biopsy of the largest one it came back negative. Now he said it is just a wait and see what happens. He is going to do a CT in 6 months.
51 year old female
2012 DX - Rectosigmoid Mass, Colon Resection, rx - radiation and chemo
2014 englarge lymph nodes, biopsy of 1 negative
07-07-2015 even bigger enlarged lymph nodes, shown on MRI & CT
2015 biopsy of bone marrow, lymph nodes-negative
3-6-2018 still enlarged lymph nodes, no diagnosis