In my opinion they shouldnt say anything about it not being cancerous if there is a lump without doing a biopsy. I had a lump that I found back in Feb they did ultrasounds, mamo's, and a MRI and still couldnt find anything. They did notice it grew though within that few months. I went for a biopsy this october and it was breast cancer. I am 25 years old and no family history or anything like that before. So to answer your question I would get a biopsy if you noticed any change bc if I would gotten in done right away, I could have probably saved my lymph nodes from being infected. Dont worry too much though because it can be anything thats for sure. I hope all is well and good luck. Keep me posted!