Clinical presentation: A 46-year-old woman was referred for evaluation of thyroid nodule. She has been treated for hypothyroidism for seven years.

Palpation. No abnormality.

Laboratory tests: TSH 0.009 mIU/L, FT4 20.5 pM/L on daily 125 microgram levothyroxine. The aTPO level was 387 U/ml at the beginning of replacement therapy.

Ultrasonography. The thyroid was hypoechogenic and had numerous discrete areas. One of them located in the middle third of the right lobe might be a pathological nodule.

Aspiration cytology resulted in Hashimoto's thyroiditis.

Suggestion. The dose of the levothyroxine was decreased to daily 100 micrograms.

Comments.

1. It is doubtful whether the lesion is a pathological nodule or not.
   
2. The histogram value of the extranodular part of the right lobe is 23.6 while that of the discrete lesion is 31.6. It means that if the reference tissue is the non-nodular part than the lesion is hyperechoic. On the other hand, if we compare the echogenicity of the lesion to a healthy thyroid than this is a moderately hypoechoic lesion.