Clinical presentation: A 39-year-old woman was referred for aspiration cytology of a recurrent nodular goiter. She has been undergone a left lobectomy for 4 years because of a large cystic nodule. Histopathology disclosed Hashimoto's thyroiditis and no nodules in a pathological sense. Two years later thyroid associated orbitopathy has developed which caused diplopia and continuous conjunctivitis despite various treatments including large dose steroid therapy. The ophthalmologist suggested removal of the right thyroid.

Palpation: The right lobe was firm and had an uneven surface.

Functional state: TSH 0.39 mIU/L on daily 87.5 microgram levothyroxine. TSAb was 2.9 U/L (normal value < 1.5).

Ultrasonography. The thyroid was moderately hypoechogenic and inhomogeneous. There were multiple discrete lesions which were partly echonormal, partly minimally hypoechogenic. None of them fit to a nodule in a pathological sense. There was no parenchyma in the left thyroid bed.

Cytology of a hypoechogenic lesion in the lower-dorsal part of the right lobe resulted in benign Hashimoto's thyroiditis.

Histopathology: Hashimoto's thyroiditis without any nodules.

Comments.

1. The largest discrete lesion in the right lobe might be a pathological nodule on ultrasound presentation. However, taking the previous histopathology into account, this likelihood is significantly decreased.
   
2. The histogram value of the extranodular part of the right lobe is 36.1 while that of the discrete lesion is 64.0. 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 (which is characterized by a 82.0 histogram value) than this is a moderately hypoechoic lesion.