Classification of thyroid carcinoma by histologic features.
| Carcinoma type | Relative frequency | Metastasis | Prognosis | Special features |
| Papillary thyroid cancer (PTC). | 50-60%, increasing trend | lymphogenic (“on the lymphatic pathway”) | 5-year survival rate: 80-90%. | Thyroglobulin (tumor marker; detection after thyroidectomy is indicative of metastases/ daughter tumors) |
| Follicular thyroid carcinoma | 20-30 % | Hematogenous (“in the bloodstream”) | 5-year survival rate: approximately 80%. | |
| Medullary thyroid carcinoma (C-cell carcinoma, MTC). | approx. 5-10 % | lymphogenic and hematogenic | 5-year survival rate: 60-70%. |
secretes calcitonin
75% of MTC are sporadic and 25% are hereditary in the setting of multiple endocrine neoplasms (MEN 2a, MEN 2b, familial MTC) |
| Anaplastic thyroid carcinoma (undifferentiated thyroid carcinoma). | 1-5 % | lymphogenic and hematogenic | Poor: median survival 6 months |
Note: The 4th edition of the WHO classification of thyroid tumors includes for the first time a group of (encapsulated) follicular tumors with uncertain/low malignancy potential (“potential of malignancy”). These are no longer referred to as carcinomas, but simply as tumors or neoplasms (neoplasms). This is the “non-invasive follicular neoplasia with PTC-equivalent nuclei (NIFTP)”.
TNM classification
T classification for papillary, follicular and medullary carcinoma.
| T | Spread of the tumor |
| T1 | <2 cm, limited to the thyroid gland |
| T2 | 2-4 cm, limited to the thyroid gland |
| T3 | > 4 cm, spread minimally beyond the thyroid gland |
| T4a | Spread beyond thyroid gland to larynx, trachea, nerves, subcutis, etc. |
| T4b | Spread beyond thyroid gland into prevertebral fascia, mediastinal vessels |
T classification for anaplastic carcinoma.
| T | Spread of the tumor |
| T4 | All propagation forms |
All forms
| N | Lymph node metastases |
| N0 | No lymph node metastases |
| N1 | Regional lymph node metastases |
| N1a | Cervical lymph node involvement |
| N1b | Lateral mediastinal lymph node involvement. |
| M | Metastases |
| M0 | No metastases |
| M1 | Distant metastases |
TNM classification for staging
| Stage | T | N | M |
| I | T1 | N0 | M0 |
| II | T2 | N0 | M0 |
| III | T3 | N0 | M0 |
| T1-3 | N1a | M0 | |
| IVA | T1-3 | N1b | M0 |
| T4a | N0-1b | M1 | |
| IVB | T4b | N0-1b | M0 |
| T1-4b | N0-1b | M1 |
Papillary/follicular thyroid carcinoma in persons <45 years of age
| Stage | T | N | M |
| I | T1-4b | N0-1b | M0 |
| II | T1-4b | N0-1b | M1 |
Anaplastic thyroid carcinoma
| Stage | T | N | M |
| IV | T1-4b | N0-1b | M0-M1 |
