The ultrasound report should mention that.
Large cysts are forming due to the internal bleeding into the small nodule.
On this forum we have a person who have had PEI injection for 3 cm cyst.
I know that it is a cold nodule, but I don't know if it is cystic.
If nodule is cystic, the aspiration following by PEI injection can be used; if nodule is solid and can take RAI after thyrogen [TSH] injection RAI ablation can be used, there is a risk to destroy non nodular tissue, therefore the latter procedure is not used for cold nodules.