Clinical presentation: A 48-year-old man was referred for evaluation with a repeatedly aspirated and recurred thyroid cyst causing complaints. There was a large nodule in the isthmic part of the thyroid. FNA resulted in benign lesion.

First row: ultrasonographic picture before sclerotherapy. The size of the lesion was 38x28x39 mm (width x depth x length).

Second row: ultrasonographic picture before the second sclerotherapy. The size of the lesion was 38x28x39 mm (width x depth x length).

Third row: 3 days after the fourth session of ethanol treatment - the cyst became more enlarged and painful. The body temperature rose to 38.2 C, the erythrocyte sedimentation rate was 50 mm/H.

Ultrasonography: The size of the nodule was 30x25x34 mm, and another hyperechogenic lesion was found dorsal to the treated lesion.
Steroid administration resulted in a prompt amelioration of the clinical symptoms. The steroid was given for 6 weeks in a decreasing dose.

Fourth row (6 weeks later): The size of the lesion was 15x8x19 mm (width x depth x length).

Fifth row (2 months after the previous visit): The size of the lesion decreased further and was 10x6x12 mm (width x depth x length).

Comment: This case illustrates the subacute granulomatous thyroiditis-like reaction which occurs in around 5% of PEI-treated patients.