정상 칼시토닌 수치를 보인 갑상선수질암 1례

Calcitonin is an important tumor marker for medullary thyroid carcinoma. Serum calcitonin is increased in most cases of medullary thyroid carcinoma. However, medullary thyroid carcinoma with normal calcitonin level has been reported very rarely. 1.2 cm sized solid thyroid nodule was suspicious for medullary thyroid carcinoma in fine needle aspiration cytology, but serum calcitonin was within the normal range. The final pathology after surgery was medullary thyroid carcinoma with positive calcitonin immunohistochemical staining. The authors present a case of calcitonin-negative medullary thyroid cancer with reviews of the mechanism, diagnosis, treatment, prognosis and follow-up of this case.