Clinical presentation: a 47-year-old woman requested a second opinion. She was treated for hypothyroidism for 3 years. An ultrasonography was performed on the request of the patient. Aspiration cytology resulted in oxyphilic variant of papillary carcinoma.

Palpation: the right lobe was firm on palpable. No discrete lesion could be palpated.

Hormonal investigation: resulted in minimally elevated TSH-level (4.38 mIU/L) on daily 87.5 microgram levothyroxin.

Ultrasonography: the thyroids were hypoechogenic. There was a hypoechogenic lesion in the upper dorso-medial part of the right lobe. The lesion displayed halo sign and a combined type 2 and type 3 vascular pattern. The borders of the lesion were not regular geometrical. The thickness of the surrounding hypoechogenic rim was varying.

Cytological diagnosis: Hashimoto's thyroiditis.

Combined clinical-ultrasound-cytological diagnosis: Hashimoto's thyroiditis with the possibility of oxyphilic variant of follicular tumor with the estimated risk of carcinoma not greater than 2%.

Taking the previous and our results into account we advised lobectomy.

Histopathology disclosed Hashimoto's thyroiditis and no nodule.

Comments.

1. The ultrasound presentation of the lesion highly resembles that of a nodule. Nevertheless, the uneven surface of the lesion and the varying thickness of the hypoechogenic rim surrounding the lesion are arguments against the possibility being the lesion a nodule in a pathological sense. Nevertheless, these arguments are absolutely not decisive but they had to be considered.

2. The cytological pattern is also remarkable. The presence of intranuclear holes led to the false diagnosis. These figures do not fit a typical inclusion. The ratio of oxyphilic cells to lymphocytes is unusually high, therefore an oxyphilic tumor has to be considered. On the other hand, follicular cells lack prominent nucleoli and a tendency to dissociate.

3. Taking the sonographic and cytological preenetation into account we gave the final diagnosis of Hashimoto's thyroiditis. Naturally, a positive cytology cannot be eliminated by a negative one. Therefore the patient had to be operated on, but on the result of the second investigation instead of total thyroidectomy only lobectomy was performed.