Clinical presentation: A 41-year-old woman was referred for evaluation of a nodular goiter detected on ultrasound screening. The lesion was held as suspicious for thyroid cancer. The patient had no complaints.

Palpation: Both lobes were firm. No nodule was palpable.

Ultrasonography. The thyroid was moderately hypoechogenic and inhomogeneous and contained multiple discrete more and less hypoechogenic areas which did not fit to a nodule in a pathological sense.

Aspiration cytology was performed from the hypoechogenic area in the dorsal part of the right lobe and resulted in Hashimoto's thyroiditis.

Hormonal investigation revealed hypothyroidism (TSH 40.3 pM/L, FT4 7.81 pM/L, anti-TPO 731 U/L).

Diagnosis: hypothyroidism caused by Hashimoto's thyroiditis.

Suggestion: increased by 25 micrograms every 10 to 14 days, setting of 100 microgram levothyroxine.

Comment. This is one of the typical ultrasound presentations of Hashimoto's thyroiditis which is frequently misinterpreted as nodular goiter. Note the shape and number of the discrete hypoechogenic areas. In the event of thyroiditis, these lesions are irregular and numerous.