Clinical data: A 69-year-old woman was referred for aspiration cytology of a thyroid nodule detected on PET-CT scan. The patient was operated on colon carcinoma 2 years ago when a PET CT scan was performed and a thyroid nodule proved to be positive. The nodule did not take up technetium while did MIBI.

Palpation: The right lobe was nodular on palpation.

Laboratory tests: TSH 2.11 mIU/L, aTPO 70 U/mL.

Ultrasound. Both lobes were moderately hypoechogenic. There was a hyperechogenic lesion in the upper part of the right lobe. The lesion had punctate echogenic granules and lines. Another, larger nodule was found in the middle-lower part of the right lobe. The latter lesion was PET and MIBI positive and had moderately hypoechogenic and echonormal parts and displayed perinodular blood flow. Both lesions showed taller-than-wide sign because the depth minimally exceeded the width in boht nodules.

Aspiration cytology from the hyperechogenic lesion resulted in Hashimoto's thyroiditis while from the larger nodule did in follicular tumor.

A right lobectomy was performed. Histopathology disclosed Hashimoto's thyroiditis and a solitary nodule which proved to be a follicular adenoma corresponding to the larger nodule.

Comment. The smaller nodule in the right lobe is darker than a healthy thyroid but brighter than the extranodular tissue. Therefore, the classification of this nodule depends on the reference of normal thyroid. If it would be the healthy thyroid, then the nodule would be classified as an EU-TIRADS 4 lesion. If the normal reference tissue would be the extranodular part, then the nodule should be regarded as an EU-TIRADS 3 lesion.