Clinical presentation: A 54-year-old woman came to a follow-up examination. She has been treated for hypothyroidism for more than 15 years. A nodule-like area was found in the isthmus 8 years ago. We suggested repeat ultrasound in 5 years. The patient had no complaints.

Palpation: The isthmic part of the thyroid was enlarged and uneven.

Laboratory tests: TSH 10.0 mIU/L on daily 75 microgram levothyroxine. The aTPO level was above 1300 U/mL eight years ago.

Ultrasound. The thyroid was moderately hypoechogenic and presented numerous discrete lesions. The right and left lobe were composed mainly of hypoechogenic areas. None of these areas corresponded to a pathological nodule. The broadened isthmus contained echonormal fields. Compared with the previous examination, the dimensions of the isthmus did not change.

Suggestion: To continue with daily 100 microgram levothyroxine. We suggested to maintain the TSH level between 0.2 and 2.5 mIU/L because of the enlargement of the isthmus.

Comment. The categorization of the isthmic nodule-like area is doubtful; this may be a pathological nodule.