A 45-year-old man undergoes total thyroidectomy with central compartment dissection for 3 cm papillary thyroid carcinoma. Final histology confirms papillary carcinoma with metastases in 4 out of 6 central compartment (level VI) lymph nodes, and microscopic extrathyroidal extension. According to AJCC 8th edition TNM staging, what is the T-category?
- A T1
- B T2
- C T3b ✓
- D T4a
Correct answer: C. T3b
Explanation
In AJCC 8th edition, T3b is defined as gross extrathyroidal extension involving the strap muscles (sternohyoid, sternothyroid, thyrohyoid, or omohyoid). Microscopic extrathyroidal extension alone does NOT upstage in AJCC 8th edition. The tumour is >2 cm but ≤4 cm (T2), but the microscopic ETE does not change the T-category in the 8th edition. However, gross invasion of strap muscles is T3b.
Reference: AJCC Cancer Staging Manual, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.