Multiple endocrine neoplasia type IIb: A clinicopathological report

The clinicopathological findings in a 12‐year‐old boy with multiple endocrine neoplasia type IIb (MEN‐IIb) are presented. He demonstrated the characteristics of a Marfanoid habitus and had mucosal neuromas of the lips, tongue, eyelids, and cornea. The enlarged right thyroid lobe showed an increased thallium‐201 chloride uptake, and the serum calcitonin level was markedly raised. A total thyroidectomy was performed. Histopathological examination showed an infiltrating medullary carcinoma of the thyroid (MCT) and metastatic spread to supraclavicular lymph nodes. Special stains, immunocytochemistry, and electron microscopy revealed mucin‐containing follicular structures lined by calcitonin‐positive and thyroglobulin‐negative tumour cells. Ultrastructurally the mucosal neuromas consisted of proliferating perineurial and Schwann cells. The serum calcitonin level fell below 300 pmol/L, and his stools returned to normal postoperatively. Because the incidence of MCT in MEN‐IIb is virtually 100%, a total thyroidectomy in high risk patients—even before clinical evidence of malignant tumours—may be the only hope of cure.