I had two thyroid fnas done three weeks apart and both say "follicular lesion of undetermined significance". what happens next? why did i get that?

Thyroidologist: It is reassuring that the biopsies didn't show malignancy. Aggressive thyroid malignancies are not common with benign biopsy results. Your thyroidologist is best to follow your case and advise you.

Indeterminate nodule: There is a standardized reporting system (bethesda) for thyroid fnas. 5 categories (benign, atypia of undetermined significance, neoplasm, suspicious for malignancy, malignant). Your result is in the second category. Studies place the probability of malignancy for your result at 5-20%. There are labs (afirma) that do gene expression testing on these samples to better define the risk of cancer.