Clinical presentation: a 65-year-old woman visited us because of a painful thyroid lump and fever which had evolved for two days.

Palpation: a painful, firm right thyroid.

Functional state: euthyroidism (TSH-level 0.83 mIU/L).

Ultrasonography : the left thyroid was intact. A large cystic lesion was found in the right thyroid.

Cytology: 8 ml purulent fluid was aspirated. Cytological diagnosis: acut thyroiditis.

Within 24 hours after administration of antibiotics the fever and the pain had resolved.

Follow-up examination 2 months later: the patient had no complaints. There was a small cystic lesion in the right thyroid with a maximal diameter of 7 mm.