Ultrasound-guided FNAB (UG-FNAB) permits direct sampling of the wall and/or the solid ... simple thyroid cysts, with an epithelial lining, and mixed nodules with a predominantly fluid component.

There is a possibility of malignant (thyroid cancer) in less than 1-5% of cystic nodules. In particular, careful observation is required in mixed cysts or cysts with many solid components.