I have had a goiter for many years. About a year ago, during a CT scan, several nodules on my thyroid were discovered, one of them was large. It was checked again, six months later and it had gotten bigger. The doctor did a biopsy and it was negative. I was told they it should be checked again in six months. I just had it checked about a month ago and it is more than twice the size it was. I am scheduled for another biopsy in 2 weeks. I just wondered how serious this is. Is the fact that the biopsy came back negitive before a good sign? What would make this nodule grow so fast?