Clinical presentation: A 49-year-old woman was referred for preoperative thyroid ultrasound examination. She has been treated for recurrent hyperthyroidism for more than 8 years.

Palpation. The thyroid was not palpable.

Laboratory tests: TSH 0.06 mIU/L, FT4 23.4 pM/L, FT3 5.07 pM/L on daily 20 mg methimazole.

Ultrasonography. The thyroid was echonormal and contained hypoechogenic areas which were not nodules in pathological sense. The echogenicity index was around 30%. The vascularization was increased.

Total thyroidectomy was performed histopathology disclosed diffuse goiter.