Clinical presentation: A 52-year-old woman has been treated for hyperthyroidism caused by Graves-disease for 6 months. Ultrasound has not been performed yet.

Palpation: no abnormality.

Functional state: euthyroidism (TSH-level 0.91 mIU/L, FT4 15.7 pM/L) on daily 5 mg methimazole.

Ultrasonography: The thyroid was moderately hypoechogenic and had two hypoechogenic nodules. The nodule in the left lobe presented coarse calcification. A halo sign could not be seen but perinodular blood flow could be detected on the Doppler mode.

Cytological diagnosis: atypical follicular tumor with greater than the average risk of cancer.

Histopathology: widely invasive, mixed trabecular-oncocytic follicular cancer.