Metastatic Medullary Thyroid Cancer in the Anterior Mediastinum: A Case Report

Medullary thyroid cancer (MTC) accounts for 5% to 10% of all thyroid cancers, and originates from the parafollicular or C-cells of the thyroid gland. More than 50% of patients present with a thyroid mass and up to 75% of these patients have locoregional lymph node metastasis at the time of diagnosis. The neuroendocrine C-cells of the thyroid gland secrete calcitonin, a relatively accurate tumor marker for MTC. Plasma basal and stimulated calcitonin measurements have been used to screen patients who are at risk of developing MTC and indispensable for the detection of residual MTC after initial surgical treatment. The overall survival rate of patients with MTC is intermediate to that of patients with differentiated thyroid cancer and anaplastic thyroid cancer. Postoperative radioiodine ablation therapy, chemotherapy and radiation therapy are generally ineffective. Surgical resection, therefore, remains the only definite treatment for patients with MTC. Unfortunately, residual MTC as indicated by elevated plasma basal or stimulated calcitonin levels is common even after apparent complete initial surgical resection. We present a case of metastatic MTC in the anterior mediastinum with review of the literatures.