Table 1.
The Bethesda System for reporting thyroid cytopathology (12).
| Category | Diagnostic Category | Predicted TBS Risk of Malignancy if NIFTP ≠ CA (%) | Risk of malignancy when non-invasive follicular thyroid neoplasm is considered cancer. | Usual Management a |
|---|---|---|---|---|
| TBS1 | Nondiagnostic or unsatisfactory | 5–10 | 2.0-19.1 | Repeat FNA with ultrasound guidance |
| TBS2 | Benign | 0–3 | 0.7-8.0 | Clinical and sonographic follow up |
| TBS3 | Atypia of undetermined significance or follicular lesion of undetermined significance | 6–18 | 9.2-30.5 | Repeat FNA, molecular testing, or lobectomy |
| TBS4 | Follicular neoplasm or suspicious for a follicular neoplasm | 10–40 | 28.9 | Molecular testing, lobectomy |
| TBS5 | Suspicious for malignancy | 45–60 | 79.6 | Near-total thyroidectomy or lobectomy |
| TBS6 | Malignant | 94–96 | 99.1 | Near-total thyroidectomy or lobectomy |
a
Actual management may depend on other factors (e.g. clinical, sonographic) besides the FNA interpretation. NIFTP, noninvasive follicular thyroid neoplasm with papillary-like nuclear features; CA, carcinoma; FNA, fine-needle aspiration. Risk of malignancy are from a meta-analysis conducted by Huy Gia Vuong et al. (13).