First session of sclerotherapy (1st row of images):

Clinical presentation: A 42-year-old woman was referred for ethanol sclerotherapy. The patient has been known harboring a cystic nodule for nine years. Eight years after the first aspiration, the cyst has recurred. At this time 9 mL fluid was removed. Weeks after the second aspiration the cyst has refilled again.

Palpation: a large elastic nodule in the right lobe.

Laboratory test: euthyroidism with TSH-level 2.8 mIU/L.

Ultrasonography: There was a large, almost completely cystic nodule in the right lobe. The dimensions of the nodule were 44, 26, and 45 mm, width, depth, and length, respectively.

20 mL brown fluid was aspirated, thereafter 3 mL ethanol was injected into the nodule.

Second session of sclerotherapy (2nd row of images):

Clinical presentation: The patients had no complaints. This time 7.5 mL brown fluid was aspirated and 2.8 mL ethanol was injected.

Further sessions and follow-up: Five sessions were administered, and a total of 11.5 mL ethanol was given. On the follow-up visits the size of the nodule was always less than 18 mm in maximal diameter.

4 years after the sclerotherapy (3rd row of images):

Clinical presentation: The patient had no complaints.

Palpation: The thyroid was not palpable.

Ultrasonography: There was a hypoechogenic nodule in the right lobe. The dimensions of the lesion were 15, 13, and 18 mm, width, depth, and length, respectively. The borders became lobulated.

Laboratory test: TSH-level 1.83 mIU/L.

Suggestion: follow-up in three years.

Comments.

1. The shape of a cyst frequently becomes irregular, lobulated after the removal of the cystic content. This change does not cause any concern just after the aspiration. However, years later it might if the investigator is not aware of the previous ultrasound pattern in a hypoechoic nodule with irregular, lobulated margins.

2. It is also worth noting that the ultrasound presentation at the last visit might raise the suspicion of extrathyroidal spread because the echogenicity of the nodule at this time was identical to the strap muscle.

3. The contour of the nodule was non-abutting at the first two occasions while the thyroid' capsule was continuous. At the last occasion, the contour became abutting and the capsule did discontinuous.