A 30-year-old woman with a known RET proto-oncogene mutation (codon 918, MEN2B) presents for prophylactic thyroidectomy. Preoperative calcitonin is 12 pg/mL (normal <10 pg/mL) and neck ultrasound shows no suspicious lymph nodes. What is the most appropriate surgical approach?

• A Observation with annual calcitonin monitoring until calcitonin exceeds 40 pg/mL
• B Total thyroidectomy with central compartment (level VI) lymph node dissection ✓
• C Total thyroidectomy without prophylactic lymph node dissection
• D Hemithyroidectomy with isthmusectomy

Explanation

MEN2B with codon 918 mutation is the highest-risk RET mutation, with medullary thyroid carcinoma developing in infancy. Prophylactic thyroidectomy is recommended within the first year of life. Even with mildly elevated calcitonin and no sonographic lymphadenopathy, central compartment dissection is indicated because micrometastases are common in MEN2B. Observation is inappropriate given the aggressive biology. Hemithyroidectomy is insufficient as MTC is multifocal. Total thyroidectomy alone without central dissection risks leaving nodal disease.

Reference: Schwartz's Principles of Surgery, 11th ed.

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Written and medically reviewed by the StethoPrep medical team.