Table 1 Bethesda system for cytological diagnosis of thyroid nodules [12]
From: The diagnostic value of ultrasonography in detection of different types of thyroid nodules
Category | Category name | Cytologic features | Malignancy risk (%) |
|---|---|---|---|
I | Non-diagnostic or Unsatisfactory (ND) | Insufficient cellularity, obscuring blood | 5–10 |
II | Benign | Normal-appearing follicular cells arranged in sheets or macrofollicls, abundant colloid | 0–3 |
III | Atypical of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) | Sparsely cellular, microfollicles, mild nuclear changes | 10–30 |
IV | Follicular lesion/suspicious for follicular lesion (FN/SFN) | Hypercellular, crowding, microfollicles, scant colloid | 25–40 |
V | Suspicious for malignancy (SFM) | Some features that suggest but not definitive for malignancy | 50–75 |
VI | Malignant | Papillary architecture, definitive nuclear changes | 97–99 |