Clinical data: A 44-year-old woman has been treated for Graves' disease for 4 years. She had a temporary elevation of FT4 level for 6 weeks which has spontaneously resolved. She came to routine follow-up examination.

Palpation: There was a firm nodule in the right thyroid.

Functional state: subclinical hyperthyroidism with TSH 0.09 mIU/L, FT4 19.1 pM/L.

Ultrasonography. The thyroids were minimally hypoechogenic with normal vascularization. There was a hypoechogenic nodule in the ventral part of the right lobe. The nodule presented irregular, lobulated margins, microcalcifications and a type 3 vascular pattern.

US-guided aspiration was performed from the nodule. Cytology resulted in papillary carcinoma.

Histopathology disclosed papillary carcinoma with extracapsular spread into the sternocleidomastoid muscle and Hashimoto's thyroiditis.