Multiple endocrine neoplasia type 2B: eighteen-year follow-up of a four-generation family.

Seven members with multiple endocrine neoplasia type 2B from a 15-member family have been followed for 18 years. All affected had the neuroma phenotype in a distribution compatible with autosomal dominant inheritance. The phenotype features have allowed 100% initial and continuing prediction of affected versus nonaffected status in as early as 1.5 years. Among the affected: immunoreactive plasma calcitonin (iCT) concentration was high in 100%; thyroid palpation was false-negative in 71%; and thyroid scintiscan was false-negative in 83%. All had total thyroidectomy, plus lymphadenectomy in three, for bilateral medullary thyroid carcinoma (MTC) or C-cell hyperplasia (in the youngest). None has died directly from MTC. The index case died at age 68 and his son at age 32 years from complications of the syndrome. All but the youngest have continuing high iCT concentrations. No patient has had parathyroid disease. During preoperative calcium infusion, immunoreactive serum parathyroid hormone concentration declined by 35% to 84% of basal. At operation, macroscopically and microscopically normal parathyroid glands were found in all. No patient has had chemical suggestion of pheochromocytomas: at postmortem the index case had no adrenal medullary disease; his son had bilateral nodular adrenal hyperplasia; his daughter has had adrenal medullary hyperplasia and a renin-secreting juxtaglomerular tumor. Initially nonaffected members remain so.