Clinical presentation: a 34-year-old woman was referred for the evaluation of a newly discovered nodule.

Palpation: a moderately enlarged right lobe with a nodule in the upper pole.

Functional state: euthyroidism (TSH-level 1.18 mIU/L).

Ultrasonography: the basic echo structure of the thyroid was normal. There were 2 hypoechogenic nodules in the right lobe next to each other. The larger one presented pronounced intranodular blood flow and signs of perinodular vascularization.

Cytological picture: there is no colloid in the background. Thyrocytes occur in clusters of microfollicles with vascularization. Follicular cells exhibit variability in size but there isn't any significant atypia present.

Cytological diagnosis: follicular tumor with the possibility of autonomously functioning nodule.

Scintigraphy disclosed a "hot" nodule in the upper 2/3 of the right lobe.

Comment: there were two signs favoring the possibility of an autonomously functioning nodule. Firstly, the increased intranodular blood flow with perinodular vascularization. Secondly, the vascularization seen on the cytological smear.