Clinical data: a 38-year-old woman was referred for aspiration cytology of a newly detected thyroid nodule.

Palpation: a nodule in the left lobe.

Result of blood tests: euthyroidism (TSH-level 1.67 mIU/L).

Ultrasonography: the thyroids were echonormal. There was a moderately hypoechogenic-echonormal nodule in the left lobe. The nodule displayed a halo sign but neither perinodular nor intranodular blood flow.

Cytology: resulted in follicular tumor.

Histopathology: disclosed follicular adenoma.

Comments:

1. The presence of halo in the absence of unequivocal perinodular blood flow is a very rare situation in the case of a follicular tumor.

2. The risk of a follicular carcinoma was higher than the average considering the enlarged atypical cells and the irregular, abortive microfollicles.