Tumor Tip of the Week 1-08-2024 Microscopic vs Gross Extrathyroidal extension invading only strap muscles - Omega Healthcare

Tumor Tip of the Week 1-08-2024 Microscopic vs Gross Extrathyroidal extension invading only strap muscles

Tumor Tip header image

Scenario:

  • SCAN TEXT: 05/09/2024 Thyroid US- 3.5 cm nodule in Right thyroid lobe. No extrathyroidal mass or LAD. Impression: Dominate R thyroid nodule, mildly suspicious
  • PATH TEXT:
    • 05/14/2024 Right Thyroid FNA cytology-Papillary Thyroid Carcinoma
    • 09/04/2024 Right Hemithyroidectomy
      • TUMOR SITE: Right lobe inferior
      • TUMOR SIZE: 3.5 cm in greatest dimension
      • HISTOLOGIC TYPE: Invasive encapsulated follicular variant of papillary carcinoma
      • TUMOR NECROSIS, ANGIOINVASION, LYMPHATIC INVASION: Not identified
      • EXTRATHYROIDAL EXTENSION: Present, focal microscopic strap muscle invasion only, with no clinical/macroscopic evidence of invasion
  • OPERATIVE TEXT: 09/04/2024 Right hemithyroidectomy-Thyroid was grossly notable for large R thyroid nodule. No pathologically enlarged or abnormal appearing LNS were identified.

Question: How would EOD Primary Tumor be assigned?

  • 200 Microscopic extrathyroidal extension, Extrathyroidal extension, NOS
  • 300 Gross extrathyroidal extension invading:

Pericapsular soft tissue/connective tissue

Strap muscle(s) Omohyoid, Sternohyoid, Sternothyroid, Thyrohyoid

Answer: 200 Microscopic extrathyroidal extension, Extrathyroidal extension, NOS

Rationale: This patient had focal microscopic extrathyroidal extension present per the 09/04/2024 path report, the path report also noted no clinical/macroscopic evidence of invasion. There also was no documentation to suggest the patient had gross (macroscopic) extrathyroidal extension on the Op Note.

EOD Manual

  • Note: Extrathyroidal extension includes minor (microscopic) extension through the thyroid capsule which is identified only on microscopic examination (see code 200) to gross (macroscopic) extrathyroidal extension, which is documented in the operative report and involves major structures (see codes 300, 400, 600, and 700).
  • If the only information available is “extrathyroidal extension” and cannot determine whether it is microscopic or gross, code 200.
  • If the only information is “gross extrathyroidal extension” and the involvement of major structures cannot be determined, code 750

AJCC: This would be assigned a pT2 due to size of tumor 3.5cm [T3 would only apply if there was Gross extrathyroidal extension invading only strap muscles]

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