Hi there. I had a mammo and ultrasound back in 2010 and they found an enlarged lymph node as well. I had a biopsy done and it turns out I have Multicentric Castlemans Disease which is an auto immune disorder of the lymph nodes that mimics lymphoma. I have had three surgeries to removed nodes, chemo, and a year on Thalidomide. I have been in remission but have new lumps in the past month and have to get tested again. Castlemans is a RARE and fairly unknown disease. Usually it is not caught because it will turn into lymphoma if not addressed. I would ask to have a biopsy done. Good luck!