Clinical presentation. A 59-year-old woman was referred for aspiration cytology of a "cold" nodule. She was first diagnosed having Hashimoto's thyroiditis 23 years ago. Recently she had complaints suggesting hyperthyroidism. On evaluation subclinical hyperthyroidism was disclosed. Scintigraphy revealed a "hot" nodule in the right and a "cold" nodule in the left lobe.

Palpation: The thyroid was not palpable.

Laboratory tests: TSH 0.04 mIU/L, FT4 15.4 pM/L, FT3 3.37 pM/L, aTPO was > 3000 U/mL, TSAb 0 U/L.

Ultrasound. The thyroid contained multiple discrete areas of various echogenicity. There was no nodule in the right lobe. There was an echonormal nodule in the left lobe according to the cold area on scintiscan. While there were no nodules in pathological sense in the right lobe, the lesion in the left lobe is very likely a nodule in pathological sense.

Aspiration cytology from the right nodule resulted in benign lesion.

Suggestion. We offered a wait-and-see. Three months later hypothyroidism has developed with spontaneously resolved another 6 months later.

Comments.

1. The isotope uptake is heterogeneous in Hashimoto's thyroiditis. The overinterpretation of increased uptake as an autonomously functioning nodule is a relatively frequent failure.

2. Although the nodule in the left lobe was echonormal and therefore not a candidate for aspiration cytology, the most frequent situation when an echonormal nodules is malignant is in the event of chronic lymphocytic thyroiditis.