Prophylactic neck surgery for second-generation multiple endocrine neoplasia type 2B.

There is no evidence-based guidance on the extent of prophylactic neck surgery for second-generation multiple endocrine neoplasia type 2B (MEN 2B), a newly emerging entity in the molecular era. In this investigation of MEN 2B children who inherited the M918T RET germline mutation from a phenotypically affected MEN 2B parent, 6 MEN 2B children (4 girls and 2 boys) from 5 MEN 2B parents (4 mothers and 1 father) were identified. None of the 6 second-generation MEN 2B children who had preoperative calcitonin serum levels between 2 and 105 pg/mL and underwent prophylactic total thyroidectomy before the age of 4 years after receiving a positive RET gene test harbored node metastases. There was no recurrent laryngeal nerve palsy or postoperative hypoparathyroidism. Within the limitations of this study, total thyroidectomy alone is adequate therapy for second-generation MEN 2B children aged 1-4 years old with preoperative calcitonin serum levels ≤100 pg/mL.