Clinical presentation: A 51-year-old man was referred for evaluation of a thyroid nodule discovered by the patient himself.

Palpation: a firm nodule in the right lobe.

Result of blood test: TSH 1.20 mIU/L.

Ultrasonography. The thyroid was echonormal. A large cystic nodule occupied almost the entire right lobe. The nodule had echonormal solid parts. The type of the cyst was doubtful before aspiration of 14 mL brown fluid, however thereafter it became evident that this is a central-type cystic nodule.

Aspiration cytology resulted in non-diagnostic cystic lesion.

Suggestion: Repeat ultrasound in a year. If the cyst refills than sooner.

Comment.

1. The echogenicity of a relatively large solid part of a cystic lesion frequently changes after aspiration. While before aspiration the acoustic enhancement may deceptively make the solid part brighter, after the removal of the fluid the solid part frequently becomes darker. The latter situation is the reality, therefore it seems to be more realistic to describe the echogenicity of the solid part of a mixed nodule after the aspiration of cystic content.
2. Regarding the nodule borders this is a typical example of non-pathological lobulation caused by removal of cystic fluid. The issue is that we can meet such patient years after the original examination and not aware of the ultrasound pattern before aspiration.