Clinical data: A 71-year-old woman was referred for follow-up evaluation of hypothyroidism which has been known and treated for more than 20 years.

Palpation. No abnormality.

Laboratory test: TSH 1.27 mIU/L. The aTPO level was 829 U/mL at the time of diagnosis of hypothyroidism.

Ultrasound. The thyroid was atrophic. Basically the thyroid was moderately hypoechogenic and had more and less hypoechogenic areas. None of the areas corresponds to a pathological nodule. The lesion in the dorsal part of the right lobe presented both taller-than-wide and taller-than-long shape.

Cytology was performed form the lesion in the dorsal part of the right lobe and resulted in Hashimoto's thyroiditis.

Comment. As in the event of other suspicious ultrasound charateristics, irregular shape can be interpreted only in pathological nodules but not in more active foci of thyroiditis.