Four cases of medullary thyroid carcinomas associated with multiple endocrine neoplasia 2B with rearranged during transfection codon M918T mutation in the same family

OBJECTIVE: To evaluate the usefulness of preoperative serum calcitonin (sCT) in patients with nodular disease without suspicion of medullary thyroid carcinoma (MTC) in history or cytology. PATIENTS AND METHODS: sCT was measured before thyroidectomy in 494 patients with nodular disease who had no family history of MTC or multiple endocrine neoplasia type 2, and no cytological suspicion of MTC. RESULTS: Basal sCT was < 10 ng/mL in 482 patients and none of them had MTC. One patient with basal sCT > 100 pg/mL had MTC. Among the 11 patients with basal sCT between 10 and 100 pg/mL, MTC was diagnosed in only one. The two patients with MTC were submitted to total thyroidectomy, combined with elective lymph node dissection indicated exclusively based on hypercalcitoninemia, and sCT was undetectable after six months. CONCLUSIONS: Preoperative sCT is useful for the detection of sporadic MTC in patients with nodular disease, even in the absence of suspicious history or cytology.