Clinical presentation: a 31-year-old woman requested a second opinion. On previous ultrasonography a 'multinodular goiter' was diagnosed with a 'suspicious hypoechogenic nodule with microcalcification'. The result of FNAC was 'Hürthle-cell tumor or Hashimoto's thyroiditis'. She wanted a second investigation before surgery.

Palpation: both thyroids were moderately firm. No nodule could be palpated.

Results of blood tests: euthyroidism with TSH-level 1.71 mIU/L, FT4 14.0 pM/L, anti-TPO < 10 IU/mL.

Ultrasonography: the thyroid was composed of small hyperechogenic areas and one hypoechogenic lesion surrounded with a halo. The size of these lesions were between 5 mm and 13 mm. The vascularization was increased within the hypoechogenic lesion in the right lobe. It contained one small hyperechogenic granule.

Cytological picture: no colloid in the background. Loose clusters of oxyphilic cells were mixed with lymphocytes. The Hürthle-cells had fine chromatin structure, most of them did not contain prominent nucleoli. Although the possibility of a Hürthle-cell tumor could not be fully excluded, it's probability was relatively low.

Combined ultrasonographic-cytological diagnosis: benign Hashimoto's thyroiditis.

The patient had great fear because of the first diagnosis and went on operation.

Histopathology: benign Hashimoto's thyroiditis with no nodule.

Comments.

1. The US pattern was very specific for the so-called micronodular form of Hashimoto's. In this case the lesions were really pseudolobules of the thyroid divided by connective tissue.

2. The sensitivity of the anti-TPO determination is around 90% and significantly worse in euthyroid state of Hashimoto's thyroiditis.

3. A cytopathologist must be aware of his or her responsibility. If the phrase 'tumor' is present on the cytological report, in almost all cases the patient will be operated on.

4. This case is a very good example that proves the need for a new diagnostic system. The sonographic pattern itself is not calming, the cytological picture is not fully calming. However, these together proved that this case is a benign Hashimoto's thyroiditis.