Abstract
Multiple endocrine neoplasia type 2B (MEN 2B), an autosomal dominant syndrome, involves endocrine tumors caused by RET protooncogene germ-line mutations in chromosome 10. The case we report, initially suspected in jaw deformity surgery, was a 19-year-old man whose malocclusion was found in a school health checkup. In surgery, his somewhat abnormal buccal mucosa and mandible were biopsied and pathological findings indicated multiple mandibular and buccal mucosal neuromas suggesting de novo MEN 2B. Whole-body examination confirmed diagnosis, showing medullary thyroid carcinoma, megacolon, prominent corneal nerves, and mucosal tongue and lips neuromas. Gene examination showed germ-line mutations of the RET protooncogene affecting codon 918 in exon 16.
Medullary thyroid carcinoma was treated by total thyroidectomy with central compartment and bilateral neck dissection. Pathological analysis revealed multiple bilateral lobe cancer foci and one central-compartment lymph-node metastasis were detected pathologically. Normal calcitonin and CEA serum levels proved the biochemical cure for medullary thyroid carcinoma 7 months postoperatively.
MEN 2B-associated medullary thyroid carcinoma is more aggressive than that without known gene mutations, necessitating early diagnosis and close follow-up. Findings of multiple oral-cavity neuromas thus mandate examination for MEN 2B.
