Table 1 Thyroid imaging reporting and data system (TIRADS) and the Bethesda System for Reporting Cytopathology (ref. 6, 8, 9)

TIRADS 1

Normal thyroid gland.

I. Nondiagnostic or unsatisfactory.

-

TIRADS 2

Benign conditions (0% malignancy).

 Cyst fluid only.

TIRADS 3

Probably benign nodules (5% malignancy).

 Virtually acellular specimen.

TIRADS 4

Suspicious nodules (5–80% malignancy rate). A subdivision into 4a (malignancy between 5 and 10%) and 4b (malignancy between 10 and 80%) was optional.

 Other (obscuring blood, clotting artifact, etc.).

TIRADS 5

Probably malignant nodules (malignancy >80%).

II. Benign.

0-3

TIRADS 6

Category included biopsy proven malignant nodules.

 Consistent with a benign follicular nodule (includes adenomatoid nodule, colloid nodule, etc.).

 Consistent with lymphocytic (Hashimoto) thyroiditis in the proper clinical context.

 Consistent with granulomatous (subacute) thyroiditis.

III. Atypia of undetermined significance/follicular lesion of undetermined significance.

5-15

IV. Follicular neoplasm/"suspicious" for follicular neoplasm. Specify if Hürthle cell type.

15-30

V. Suspicious for malignancy.

60-75

 Suspicious for papillary carcinoma.

 Suspicious for medullary carcinoma.

 Suspicious for metastatic carcinoma.

 Suspicious for lymphoma.

VI. Malignant.

97-99

 Papillary thyroid carcinoma.

 Poorly differentiated carcinoma.

 Medullary thyroid carcinoma.

 Undifferentiated (anaplastic) carcinoma.

 Squamous cell carcinoma.

 Carcinoma with mixed features.

 Metastatic.