ACTA ENDOCRINOLOGICA (BUC)

Background. Riedel thyroiditis is a rare, chronic inflammatory disease of the thyroid, characterized by a dense fibrosis that replaces normal thyroid parenchyma. In literature descriptions of individual cases of Riedel thyroiditis can be found. Case report. We present an euthyroid patient with multinodular goiter who was diagnosed with Riedel thyroiditis using pathology. Imaging diagnostic methods (Ultrasonography, X-ray computed tomography, Magnetic resonance imaging, Radionuclide imaging) or various tests of thyroid function cannot confirm the diagnosis of Riedel thyroiditis. Conclusion. Only level of IgG4 may be helpful for the diagnosis of Riedel thyroiditis, while pathology is used for its definitive confirmation.