Bethesda System
Classes Description Risk of malignancy (Percentage) Usual management
I Non-diagnostic or Unsatisfactory 1-4 Repeat
II Benign 0-3 Follow up
III Follicular Neoplasm or Suspicious for a Follicular Neoplasm 5-15 surgical lobectomy
IV Atypia of Undetermined Significance or Follicular Lesion of Undetermined Significance 15-30 surgical lobectomy
V Suspicious for Malignancy 60-75 near-total thyroidectomy or surgical lobectomy
VI Malignant 100 near-total thyroidectomy or surgical lobectomy
Table 8: Diagnostic categories, associated risk of malignancy and clinical management [20].