What is follicular thyroid carcinoma?

10-15%, 40-50 yrs old. Macroscopy well demarcated nodule or widely invasive mass, DD: Adenoma. Microscopy: most composed of uniform cells forming small follicles, Hurthle cells may be seen, may be widely invasive infiltrating the thyroid parenchyma and extrathyroid soft tissues/minimally invasive, latter one is sharply demarcated may be impossible to distinguish from follicular adenoma, only seen by histology to see capsular invasion