Table 1. The Bethesda System for Reporting Thyroid Cytopathology: implied risk of malignancy and recommended clinical management in 2009 (before NIFTP) and in 2018 (after NIFTP).
| Diagnostic category | Risk of malignancy (1st edition 2009) | Risk of malignancy without NIFTP (2nd edition 2018) | Risk of malignancy with NIFTP (2nd edition 2018) | Usual management (1st edition 2009) | Usual management (2nd edition 2018) |
|---|---|---|---|---|---|
| Non-diagnostic or unsatisfactory | Not assessed | 5–10% | No significant changes | Repeat FNA with ultrasound guidance | No significant changes |
| Benign | 0–3% | No significant changes | No significant changes | Clinical and sonographic follow-up | No significant changes |
| Atypia of undetermined significance or follicular lesion of undetermined significance | 5–15% | 10–30% | 6–18% | Repeat FNA with ultrasound guidance | Repeat FNA, molecular testing, or lobectomy* |
| Follicular neoplasm or suspicious for a follicular neoplasm | 15–30% | 25–40% | 10–40% | Lobectomy | Molecular testing, lobectomy** |
| Suspicious for malignancy | 60–75% | 50–75% | 45–60% | Near-total thyroidectomy or lobectomy | Near-total thyroidectomy or lobectomy*** |
| Malignant | 97–99% | No significant changes | 94–96% | Near-total thyroidectomy | Near-total thyroidectomy or lobectomy*** |
*, after consideration of clinical and sonographic features, investigations such as repeat FNA or molecular testing may be used to supplement malignancy risk assessment instead of proceeding directly with a strategy of either surveillance or diagnostic surgery (5); **, after consideration of clinical and sonographic features, molecular testing may be used to supplement malignancy risk assessment data instead of proceeding directly with surgery (5); ***, molecular testing may be used if the result is expected to alter the extent of surgery (5). Adapted with permission from (21). FNA, fine needle aspiration; NIFTP, non-invasive follicular thyroid neoplasm with papillary-like nuclear features.