First examination (first and second rows of images):

Clinical presentation: A 25-year-old woman requested evaluation of a neck lump which was discovered by herself 3 weeks ago.

Palpation: an elastic nodule in the left lobe.

Result of blood test: TSH 1.43 mIU/L.

Ultrasonography. The thyroid was echonormal. There was a dominantly cystic nodule in the left lobe. The lesion had echonormal solid area.

3.5 mL brown fluid was aspirated. The cyst has begun to refill during the aspiration of the cystic content. Cytology resulted in benign cystic lesion.

First session of sclerotherapy (third row of images):

Clinical presentation. Half a year has passed since the previous meeting. The patient noticed that the cyst has recurred 3 weeks ago.

Palpation: an elastic nodule in the left lobe.

Ultrasonography. The pattern was the same as what we saw at the first examination except for an increase in nodule volume.

16 mL brown fluid was aspirated, then 3.8 mL ethanol was injected. The therapy caused no complaints.

Second session of sclerotherapy (fourth row of images):

Clinical presentation. The patient had no complaints.

Ultrasonography. A minimally hypoechoic-echonormal mass has appeared within the nodule. By compression, we could detect flow of the mass.

This time 2.5 mL fluid was removed and 4.8 mL ethanol was injected. At the end of the session the patient felt a straining pain which lasted for half minute.

Fifth session of sclerotherapy (fifth row of images):

Clinical presentation. The patient had felt the nodule smaller since the third session and the compression felt in recumbent position has stopped.

Ultrasonography. A minimally hypoechoic-echonormal mass has appeared within the nodule. By compression, we could detect flow of the mass.

This time 1.0 mL ethanol was administered.

Two months after the sclerotherapy (sixth row of images):

Clinical presentation. The patient had no complaints.

Palpation: no abnormality.

Result of blood test: TSH 1.95 mIU/L.

Ultrasonography. The nodule has become much smaller. A heterogeneous mass has replaced the cystic content. The nodule presented taller-than-wide shape, the borders became irregular, lobulated. The nodule became avascular.

Suggestion: ultrasound in 4 months.

Comments. Several lessons can be learned from this case study.

1. The cyst was refilling during the aspiration - by removing cystic fluid, we can release compression of veins.
   
2. The echogenicity of the cystic portion has changed after the first session, a seemingly solid area has appeared. However, by compressing the nodule, this mass presented flow, which proved that this was in fact, at least in part, fluid.
   
3. After the shrinkage of the nodule, both the shape and margins have become irregular, taller-than-wide sign and lobulation have appeared.
   
4. The solid part of the nodule became avascular after the first session of sclerotherapy.