Clinical presentation: a 54-year-old woman with a multinodular goiter discovered on a routine examination. The nodule in the left lobe was firm on palpation.

Functional state: euthyroidism with TSH-level 1.22 mIU/L.

Ultrasonography: the right lobe contained multiple nodules with different echogenicity. There were two nodules in the left lobe. One of them was hypoechogenic with patchy hyperechogenic areas. There was an enlarged lymph node above the left lobe.

Cytological picture: no colloid in the background. A very cellular picture. Polygonal cells, many triangular forms with eccentric nuclei predominate the smear. A few small solid nests can be observed. There are present many enlarged, highly atypical, pleomorph tumor cells. 

Cytological diagnosis: medullary cancer.

Histopathology: medullary cancer in the left lobe with metastasis to the lymph node of the neck, and there were hyperplastic benign nodules in the right lobe.