A Novel Technical Approach for Infant Thyroidectomies in Twins With MEN2B (M918T RET Codon) Highest Risk Mutations

The RET oncogene plays an important role in multiple endocrine neoplasia (MEN) type 2B and the development of medullary thyroid cancer. Highest risk amongst these RET codon mutations is M918T. Most cases of MEN type 2B are detected de novo later in childhood, however there remain instances of parental inheritance. When parenteral inheritance of a M918T mutation is confirmed after birth current guidelines recommend a prophylactic thyroidectomy in infancy. We report a case of twin boys born to a 31-year-old female with known MEN2B RET codon M918T mutation. Both boys had confirmatory testing for the M918T mutation after birth. After pre-operative investigations revealed sonographically normal thyroids, no cervical lymphadenopathy and normal calcitonin levels they both underwent prophylactic thyroidectomy at 7 months corrected gestational age. Thyroidectomies in infancy offer unique challenges including translucent parathyroid glands and airways too narrow to accommodate a standard Neural Integrity Monitor (NIM) endotracheal tube. We describe our surgical technique for an infant total thyroidectomy and fashioning of a novel NIM tube to allow for recurrent laryngeal nerve (RLN) monitoring to minimise complications in these very young patients. Both infants made a complete recovery without any significant complication. Histopathology revealed evidence of focal C Cell hyperplasia, but no malignancy in either thyroid gland. Our experience with these 2 cases highlights the importance of an experienced multidisciplinary team in infant thyroidectomies and outlines a novel technique to allow for RLN monitoring intra-operatively.