Clinical data: a 44-year-old woman was presented with fever and painful thyroid for a month. She suffered from upper airways infection 3 months before the present examination.

Palpation: both thyroids were firm and tender.

Functional state: hypothyroidism with TSH-level 6.71 mIU/L, FT4 10.7 pM/L, aTPO 641 U/mL, We 47 mm/H.

Ultrasonography: the thyroids were echonormal with around 15% hypoechogenic areas. The vascularization was increased.

Cytology: resulted in Hashimoto's thyroiditis.

Comment: the clinical and laboratory presentations of the patient were misleading even when the elevated aTPO was taken into account. The sonographic pattern was specific for lymphocytic thyroiditis. Nevertheless, in such a situation an FNAC cannot be determined superfluous.