Clinical data: A 59-year-old man was referred for regular follow-up examination. He was operated because of a diffuse goiter causing compression signs for 16 years. Histopathology revealed Hashimoto's thyroiditis. For several months he has noticed a slowly growing submental mass. One year before present investigation no abnormalities were found in the region of the neck.

Palpation: a firm, painless mass in the submental region.

Laboratory tests: euthyroidism on daily 75 microgram levothyroxine (TSH 4.56 mIU/L).

Ultrasonography: There were small hypoechogenic areas surrounded with an echonormal rim in the thyroid beds. A cystic lesion was detected in the submental region. The mass had irregular shape and presented signs of intralesional vascular pattern.

Aspiration cytology was performed and minimal amount of brown fluid was aspirated. Cytological diagnosis: suspicion of thyroid papillary carcinoma.

Wash-out thyroglobulin above 476 ng/mL, serum-thyroglobulin was 3.01 ng/mL, serum anti-hTg was 70.6 U/mL.

Histopathology: papillary carcinoma in aberrant tissue of the thyroid.