A 28-year-old man is diagnosed with MEN2B syndrome. He has mucosal neuromas, marfanoid habitus, and medullary thyroid carcinoma on genetic screening. His RET mutation is at codon 918 (M918T). According to ATA 2015 guidelines, this mutation places him in which risk category for medullary thyroid cancer aggressiveness?
- A Highest (D) risk — prophylactic thyroidectomy within the first 6 months of life or as soon as diagnosed ✓
- B Moderate risk — prophylactic thyroidectomy at age 5 years
- C High risk — prophylactic thyroidectomy at age 6 months to 1 year
- D Low risk — thyroidectomy deferred until calcitonin rises above normal
Correct answer: A. Highest (D) risk — prophylactic thyroidectomy within the first 6 months of life or as soon as diagnosed
Explanation
ATA 2015 RET mutation risk categories for MTC in MEN2: Highest risk (category D) includes codon 918 (M918T) — associated with MEN2B, the most aggressive MTC. Prophylactic total thyroidectomy is recommended within 6 months of birth or immediately upon diagnosis. High risk (category C) includes codons 634, 883 — thyroidectomy within first year. Moderate risk (category B/A) includes other codons — thyroidectomy based on calcitonin/age criteria.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.