Clinical data: a 674-year-old woman was referred for a follow-up examination. She was known harboring a large nodule for decades. I have been performed the first ultrasonograpy in this patient for 17 years when she had a nodule with the dimensions of 37x30x58 mm. She had no complaints.

Palpation: a large but inconspicuous nodule in the left lobe.

Functional state: euthyroidism with TSH 0.98 mIU/L.

Ultrasonography. The thyroid was echonormal. There was a moderately hypoechogenic nodule in the left while an echonormal nodule having small cystic areas and halo sign in the left lobe. The dimensions of this lesion was 35x29x64 mm. 

We advised ultrasound in three years, in the event of any complains at once.

Comments.

The most frequent indication of thyroid surgery in a moderately iodine-deficient area is the enlargement of the thyroid. Usually, we focus on the size of the nodule or nodules. Not infrequently we follow certain kind of rule of thumbs, i.e. a nodule larger than 3 or 4 cm is the indication of surgery. On the other hand, the real indication of thyroid oiperation is not the size of a single nodule but that of a thyroid lobe.
It is a rare situation that a nodule exceeding 6 cm in maximal diameter is not an absolute indication of surgery but if a large lesion replaces the normal parenchyma than we can face with such situation.

Many, including us, believe that larger the nodule, greater the chance for a further enlargement. On the other hand, great proprtion of thyroid nodules does not increase in size.