Unless the nodule is an autonomous functioning nodule (rarely malignant), two individual biopsies are required to conclude that a lesion is not cancer. With Thyroid RFA the nodule is not removed and sent to the pathologist for analysis. After RFA therapy, surveillance ultrasound might identify irregularities within the nodule which could be interpreted as suspicious. This interpretation may prompt further biopsies. Tissue cytology may look more atypical after RFA treatment . For that reason the assurance of benign thyroid tissue is critical prior to therapy.