Clinical presentation: A 14-year-old boy was referred for evaluation of a thyroid nodule. He was examined because of thyroid enlargement detected on routine examination.

Palpation: Both lobes were palpable. No nodules could be palpated.

Laboratory tests: TSH 2.68 mIU/L, aTPO 3 U/mL.

Ultrasound. The thyroid presented the so-called honeycombing pattern, i.e. there were numerous small hypoechogenic areas within an echonormal background. The largest hypoechogenic area was misinterpreted as a nodule on previous ultrasound examination. This field was simply the largest of the similarly hypoechogenic parts of the thyroid. Considering the body mass, the thyroid was not enlarged.

Diagnosis: Hashimoto's thyroiditis in euthyroid state.

Suggestion. TSH determination in a year.

Comment. This ultrasound pattern is itself diagnostic of autoimmune thyroiditis.