Clinical presentation: A 38-year-old woman was referred for evaluation of a newly detected hypothyroidism. She has been investigated for dysmenorrhea.

Palpation: no abnormality.

Laboratory tests: TSH 9.14 mIU/L, FT4 10.1 pM/L, aTPO above 1000 U/mL.

Ultrasonography. Both lobes were decreased in size and showed hypoechoic areas. There were several discrete areas. Except for that in the left lobe, none of these lesions corresponded to pathological nodules. There was a nodule in the left lobe which showed halo sign and perinodular blood flow. Compared with the extranodular area, the echogenicity of the lesion was iso/hyperechoic. Compared with a healthy thyroid, the lesion would be classified as a minimally/moderately hypoechoic nodule.

Cytology of the nodule in the left lobe resulted in follicular tumor. The proportion of oxyphilic cells was around 20% which did not fulfill the criteria of a Hürthle-cell tumor.

A left lobectomy was advised. Histopathology disclosed a minimally invasive follicular carcinoma and Hashimoto's thyroiditis. Detailed analysis revealed angioinvasion. Subsequently, the patient underwent a right lobectomy and radioiodine therapy.

Comment. 

1. The issue was that the nodule was found in a hypoechoic thyroid.
   • On protocols of all professional societies, the nodule had to be classified as iso/hyperechoic and because of the size of the lesion, none of the TIRADS would indicate FNA.
   • Considering the suggestion of the European Thyroid Association for defining a nodule in hypoechoic thyroids, we measured the histogram value of the salivary gland. If we compared the nodule' echogenicity to that of the salivary gland, the lesion should be classified again as hyperechoic.
   • However, if the reference tissue would be a normal healthy thyroid than the nodule should be regarded as minimally/moderately hypoechoic.
     
2. The other discrete lesions did not correspond to a pathological nodule.