AJCC 8th Edition Head & Neck Staging Guidelines

Thyroid (Medullary)

Overview

Medullary Thyroid Carcinoma

  • MTC accounts for approximately 1-2% of all thyroid carcinomas.
  • Originates from the parafollicular C cells of the thyroid gland.
  • MTC can either be sporadic or familial.
  • Hereditary MTC is associated with:
    1. MEN2A → associated with (1) MTC, (2) pheochromocytoma, and (3) parathyroid adenomas/hyperplasia.
    2. MEN2B → associated with (1) MTC, (2) pheochromocytoma, (3) mucosal/gastrointestinal neuromas, and a (4) marfanoid habitus.
    3. Familial Medullary Thyroid Carcinoma (FMTC)
  • Almost all patients with hereditary MTC and 50% of patients with sporadic MTC will have a germline mutation in the RET gene (located on chromosome 10q11).
  • Elevated CEA and calcitonin.
T-Categorization

(Same as for Differentiated Thyroid Carcinoma)

T Category Criteria
T0

No evidence of primary tumour
TX

Primary tumour cannot be assessed
T1

2 cm or smaller and limited to the thyroid.
T1a
  • 1 cm or less and limited to the thyroid.
T1b
  • > 1 - 2 cm and limited to the thyroid.
T2

>2 - 4 cm and limited to the thyroid.
T3
  • >4 cm and limited to the thyroid
  • OR any size with gross extrathyroidal extension to the straps only.
T3a
  • >4 cm and limited to the thyroid
T3b
  • Primary tumour of any size with gross extrathyroidal extension to the straps only.
T4
  • Gross extrathyroidal extension beyond the strap muscles.
T4a
  • Gross extrathyroidal extension to the trachea, esophagus, soft tissues of the neck, larynx, or recurrent laryngeal nerve.
T4b
  • Gross extrathyroidal extension invading the pre-vertebral fascia, carotid artery encasement, or mediastinal vessels.
N-Categorization

(Same as for Differentiated Thyroid Carcinoma)

N Category Criteria
NX

Regional lymph nodes cannot be assessed.
N0

No evidence of locoregional lymph node metastasis.
N0a
  • One or more cytologically or histologically confirmed benign lymph nodes.
N0b
  • No radiologic or clinical evidence of lymph node metastasis.
N1

Metastasis to regional nodes.
N1a
  • Metastasis to level VI or level VII (central compartment lymph nodes)
N1b
  • Metastasis to lateral neck nodes (I-V) or retropharyngeal lymph nodes.
M-Categorization

(Same as for Differentiated Thyroid Carcinoma)

M Category Criteria
M0

No distant metastasis
M1

Distant metastasis present
Group Staging
N0
M0		 N1a
M0		 N1b
M0		 Any N
M1
T1 I III IVA IVC
T2 II III IVA IVC
T3a II III IVA IVC
T3b II III IVA IVC
T4a IVA IVA IVA IVC
T4b IVB IVB IVB IVC

General Rules

  • Only T1 N0 M0 MTC is stage I.
  • T2-T3b N0 M0 MTC is stage II.
  • Central neck disease (N1a) upstages to stage III.
  • Lateral neck disease (N1b) upstages to stage IVA.
  • T4a disease (gross extension beyond the straps, resectable) upstages to stage IVA as well.
  • T4b disease (unresectable) upstages to stage IVB.
  • Stage IVC is reserved for the presence of distal metastasis.
CHAPTER 17. Thyroid (Differentiated) CHAPTER 19. Thyroid (Anaplastic)