INTRODUCTION: Amyloid goiter is a rare disease characterized by amyloid deposits that cause sudden growth in the thyroid gland. CASE PRESENTATION: Here we present a case of a 26-year-old woman with euthyroid amyloid goiter who presented with subacute granulomatous thyroiditis clinic. Amyloid goiter was detected as a result of core biopsy from the thyroid parenchyma of the patient with sudden thyroid enlargement. Surgery was not applied to the patient who had no pressure symptoms or signs. In systemic amyloidosis secondary to Familial Mediterranean fever, involvement was found in the heart, kidney, liver, and intestines, except for the thyroid. CONCLUSION: Amyloid accumulation should be considered in addition to anaplastic thyroid cancer and lymphoma in patients with sudden thyroid enlargement. It should not be overlooked that amyloid goiter may mimic subacute thyroiditis clinic. Systemic amyloidosis should be considered in patients with amyloid goiter, and an examination should be made to assess the presence of amyloid accumulations in other organs.
