Abstract
Mixed medullary and follicular thyroid carcinoma （MMFTC） is a rare type of thyroid cancer that shows morphological and immunophenotypical evidence of the coexistence of follicular and parafollicular cell-derived tumor populations within the same lesion. Here, we report the case of a MMFTC patient with mixed lymph node metastases. The patient was a 67-year-old man with no positive history. He had palpable masses on both thyroid lobes and swelling of multiple left neck lymph nodes and several superior mediastinal lymph nodes. Preoperative fine-needle aspiration of each region did not suggest a diagnosis of MMFTC. He underwent total thyroidectomy and left neck lymph node dissection. The left lobe nodule contained MMFTC, the right lobe nodule contained medullary carcinoma, and multiple neck lymph nodes contained medullary carcinoma, papillary carcinoma, and MMFTC. FDG-PET was useful for recognizing the preoperative region associated with the primary MMFTC and its metastases. The serum levels of thyroglobulin, calcitonin, and CEA normalized postoperatively. The patient’s condition has been healthy and there are no signs of recurrence four years after surgical treatment alone.
