Clinical presentation: A 47-year-old woman requested a follow-up examination. She has been diagnosed with a thyroid nodule for 12 years. At the first examination, FNA was not performed because the nodule did not show any suspicious signs and had a maximal diameter of 14 mm.

Palpation: a not firm nodule in the left lobe.

Laboratory tests: TSH 1.35 mIU/L, aTPO 7 U/mL.

Ultrasonography. The thyroid was echonormal and had several small discrete lesions. There was an isoechoic nodule in the ventral part of the left lobe. The lesion had halo. The nodule contained hypoechoic areas but none of them exceeded 1 cm in maximal diameter.

Cytology of the nodule resulted in follicular tumor.

A right lobectomy was performed. Histopathology disclosed a minimally invasive follicular carcinoma. The patient was reoperated and underwent on radioiodine therapy. On the post-therapy scan, two metastatic foci were found in the lung.

Comment. 

1. The nodule may be classified either as a homogeneous, isoechoic nodule or as a dominantly isoechoic nodule having hypoechoic areas.

2. This case study points to one of the most important concerns about the TIRADS systems. At the initial examination, no TIRADS would indicate FNA because all would classify this nodule either as an intermediate or as a low risk lesion, AACE/ACE-AME TIRADS and all other TIRADS, respectively. Considering the suggestions on FNA in these categories, none of the system suggest FNA. It is well-known that the basis of TIRADS are ultrasound features characteristic of papillary cancer. On these features, up to more than 50% of follicular cancers smaller than 2 cm in maximal diameter, would not undergo on FNA.