Clinical presentation: a 64-year-old hypothyroid woman requested a second opinion. She was treated for hypothyroidism for 19 years. She was treated in another hospital. Six months before the present examination FNAC performed from a nodule in the right thyroid resulted in atypia of unknown significance, repeated FNAC resulted in papillary carcinoma.

Palpation: both thyroids were firm. No nodule was palpable.

Functional state : euthyroidism on daily 137.5 microgram levo-tiroxine (TSH 1.72 mIU/L, FT4 10.3 pM/L).

Ultrasonography: the thyroids were hypoechogenic and displayed fibrotic changes. There was a hyperechogenic lesion in the central part of the right lobe with a type 3 vascular pattern.

Cytology: dispersed follicular cells and papillary fragments were found mixed with heterogeneous lymphoid cells. Follicular cells contained inclusions and grooves. The cytological picture itself was suspicious for a papillary carcinoma with an estimated risk of cancer around 50% based solely on FNAC.

Combined cytological-sonographic diagnosis: Hashimoto's thyroiditis and suspicion of papillary carcinoma. Taking the sonographic pattern into account, the risk of papillary cancer was estimated around 20%.

Instead of thyroidectomy we advised only lobectomy.

Histopathology: Hashimoto's thyroiditis without any nodule.

Comments:

1. This case demonstrates the limitations of our knowledges. The thyroid of a patient with significant risk of papillary cancer proved to be non-nodular. Facing with such cytological pattern the patient had to be operated on. The Bethesda reporting system had no relevance in such cases. Why we think that cytological properties leading to atypia of unknown significance at first occasion will resolve over half a year? And if we do not find atypia on the smear on a second occasion why we have not to think that we missed a small focus of a tumor at second occasion?

2. Nevertheless, the combination of sonographic and cytological properties although could not save the patient from an operation but saved the patient from an operation with unnecessary radicality.