From all the research I've done on my own nodule (my biopsy came back "suspicious for follicular neoplasm"), atypical of undetermined significance is a slightly better FNA result. The medical literature seems to suggest the chance of malignancy is 5-10%, about the same as it is for any nodule. That being said, now that you know it has abnormal cells in it, you have to make some choices. If it's not causing you any problems and is on the smaller side, I think your doctor's recommendation is very reasonable. It may not grow or it may. If it does then you would probably want to get it out. Because I'm in the same situation as you, I understand your anxiety. My chance of cancer is somewhat higher (20-30%) and my nodule is fairly sizable. I will therefore be having thyroid surgery tomorrow. Yes, the ambiguity frustratingly sucks!