Clinical presentation: A 43-year-old woman was referred for evaluation of a nodular goiter. The patient has been treated for hypothyroidism for more than 20 years. She visited another endocrinologist who performed an ultrasound examination and detected a nodule in the left lobe.

Palpation: no abnormality.

Laboratory tests: TSH 2.90 on daily 75 microgram levothyroxine.

Ultrasound. Both lobes were hypoechogenic. There was an echonormal area in the left lobe, which was infiltrated by hypoechogenic tissue. It is doubtful whether the echonormal area is a true nodule or the only intact part of the thyroid.

Aspiration cytology was performed from the lesion and resulted in Hashimoto's thyroiditis.

Comments.

1. The size of the lesion argues for a true nodule, while the irregular borders stand against a pathological nodule. We described this area as a nodule-like lesion on ultrasound report.

2. Usually if we see a lesion with infiltrative borders, it is evident that the lesion itself is responsible for the invasion. However, in the event of an underlying thyroiditis, the situation might be completely the opposite, as happened in this case. The nodule borders seem to be irregular, but this is caused by the infiltration of the underlying thyroiditis. Essentially, this is not a pathological lobulation or spiculation of the nodule-like lesion.

3. The histogram value of the nodule is 84.7. It means that the lesion belongs to the iso/hyperechogenic nodules both in the relative and absolute term, compared to the non-nodular part and to the healthy thyroid, respectively.