Clinical data: a 39-year-old woman was referred for FNAC of the thyroid because of a newly-developed nodule. She had been operated with colon cancer with hepatic metastasis 1 year before the thyroid examination.

Palpation: a firm nodule in the right lobe.

Functional state: euthyroidism.

Ultrasonography: a hypoechogenic inhomogeneous nodule in the right thyroid.

Cytological diagnosis: papillary cancer.

Histopathology: metastasis of a colon cancer to the thyroid.

The postoperative evaluation of the patient revealed metastasis to the lung and to the liver.

Comments: we made two mistakes.

1. At the time of aspiration cytology we were not aware about the previous operation on colon cancer.

2. This was a clear misinterpretation of the cytological pattern: although the cytological picture resembles that seen in papillary cancer, the cytological pattern corresponds to colonic cancer.