C-CELL HYPERPLASIA AND MEDULLARY-THYROID CARCINOMA IN PATIENTS ROUTINELY SCREENED FOR SERUM CALCITONIN

Routine screening of calcitonin serum levels in patients with nodular thyroid disorders has led to an increased rate of total thyroidectomie s. We investigated prevalence and interrelationship of C-cell hyperpla sia (CCH) and medullary thyroid carcinoma (MTC) in patients with thyro id and parathyroid disorders that showed increased calcitonin serum le vels detected by routine screening. Within two years, 30 (mean age, 60 +/- 14 years) of 667 patients had a pentagastrin-stimulated calcitoni n level of more than 100 pg/mL. All 30 underwent total thyroidectomy a nd were tested for germ-line mutations of the ret protooncogene. Entir e surgical specimens were blocked, and C-cell disorders were assessed using conventional histology and immunohistochemistry. C-cell hyperpla sia was defined by the presence of more than 50 C cells/1 low-power fi eld in both lobes and was classified as focal. diffuse, nodular, or ne oplastic. Nineteen patients (female/male = 14/5) had MTC, and 11 males but no females had CCH only. Six of 16 patients with sporadic MTC had concomitant CCH. Three patients were index cases of new MTC families. We conclude that MTC with concomitant CCH is an unreliable marker for hereditary MTC risk and that CCH has a preneoplastic potential in the absence of germ-line mutations. In this series, CCH alone was not fou nd in females.