Clinical data: a 82-year-old man was referred for an evaluation of a rapidly increasing mass in the left thyroid. The tumor evolved over 3 weeks and caused palsy of the left recurrent nerve and dysphagia.

Palpation: a very hard, fixed left thyroid.

Functional state : euthyroidism (TSH 2.32 mIU/L, FT4 18.6 pM/L).

Ultrasonography revealed an enlarged left thyroid which was composed of multiple hypoechogenic, inhomogeneous nodules.

Cytological report: anaplastic cancer.

Histopathology disclosed anaplastic cancer.