Clinical presentation: a 62-year-old woman was operated on Graves' disease 15 years before. 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.

Results of blood tests: 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.

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.