Clinical presentation: a 26-year-old woman was presented with a newly discovered nodule.

Palpation: a nodule in the right side of the isthmus.

Functional state: euthyroidism with TSH-level of 1.56 mIU/L.

Ultrasonography: a moderately hypoechogenic nodule in the isthmus. The nodule exhibited microcalcifications. The vascularization was not specific. Neither a halo sign nor perinodular blood flow was observed.

Cytological picture: diffuse colloid precipitate. Thyrocytes in regular clusters composed of micro- and normofollicles. Follicular cells did not exhibit any significant atypia.

Cytological diagnosis: a benign follicular proliferation.