First examination (first and second rows of images):

Clinical data: A 62-year-old woman was operated on Graves' disease 15 years ago. She did not require replacement therapy. She was now referred for an evaluation of palpation and 7 kg weight loss and recurrent nodule described on ultrasonography.

Palpation: an operated thyroid without any abnormalities.

Result of blood test: hyperthyroidism (TSH undetectable, FT4 31.3 pM/L).

Ultrasonography. A diffusely hypoechogenic thyroid was found with small more hypoechogenic areas. The hypoechogenic area was surrounded with echonormal tissue. This pattern was interpreted falsely as a nodule by a previous examiner. The vascularization was average.

Cytology was performed from the right thyroid. Cytological diagnosis: benign pattern corresponding to hyperthyroidism.

TSAb proved to be minimally elevated 2.4 U/mL (normal value below 1.5).

Thyrostatic therapy was started and the patient was treated with radioiodine 3 months later.

Second examination 6 years later (third row of images):

Clinical data: The patient came to a routine follow-up. She had no complaints which could be related to thyroid disease.

Palpation: no abnormality.

Result of blood test: TSH 7.03 mIU/L on daily 75 microgram levothyroxine.

Ultrasonography. The remnants of the thyroid lobes have significantly decreased. Otherwise, the pattern remained the same: a central larger hypoechoic field was surrounded with echonormal tissue.

Suggestion: to increase the dose of the levothyroxine to daily 100 microgram.

Comment. It is worth analyzing the ultrasound presentation - a large hypoechogenic area is surrounded with a thick echonormal rim. Although this pattern seems to be a nodule, it is one of the most characteristic appearances of a subtotally resected thyroid.