C-cell disease of the thyroid gland in multiple endocrine neoplasia, type 2b.

Multiple endocrine neoplasia, type 2b (MEN 2b) is a disorder characterized by C-cell disease of the thyroid gland (medullary carcinoma or C-cell hyperplasia, or both), pheochromocytoma, ganglioneuromatosis, and skeletal and connective tissue abnormalities. The medullary thyroid carcinoma (MTC) is bilateral and multicentric; it metastasizes locally and distally, often before the disease is recognized. Histologically proven C-cell disease was present in 89 of the 107 patients (83%) reported with the condition, including 17 Mayo Clinic patients (average age at diagnosis, 19.2 years). Nineteen of the 107 patients (18%) died of MTC (average age at death, 25.3 years); 9 (8%) succumbed to pheochromocytoma, 7 of these also having metastatic MTC; 13 12%) died of other or unknown causes, but 2 of these had disseminated MTC as well; 29 (27%) survive with metastatic MTC; an additional 21 (20%) are alive, but concentrations of plasma immunoreactive calcitonin (iCT) have not been measured; 6 more (6%), 5 of whom had thyroidectomy before the age of 12 years, are alive with normal plasma concentrations of iCT; and the remaining 10 (9%) have been lost to follow-up. Survival of patients with MEN 2b after operation was reduced when compared with that of a control population -- 80% versus 99% at 5 years and 50% versus 98% at 10 years. The only effective treatment for MTC is total thyroidectomy before metastasis occurs. "Cure" of MTC in patients with MEN 2b has generally been obtained in those having total thyroidectomy before age 12. Therefore, in young patients suspected of having MEN 2b, we recommend prompt evaluation of C-cell function by measurement of stimulated concentrations of iCT and treatment by total thyroidectomy if results are abnormal.