Medullary and papillary thyroid carcinomas in a patient with a C634Y mutation in the RET proto-oncogene: A case report.

A 41 year old man presented with a familial history of multiple endocrine neoplasia type 2A (MEN2A) and severe hypertension. Rearranged during transfection (RET) gene sequencing confirmed a Cys634Tyr mutation of TGC to TAC. Total thyroidectomy and bilateral neck dissection were performed and the pathological assessment revealed a medullary thyroid carcinoma (MTC), 0.6 cm in size on the right side (number of lymph nodes: 0/2, 0/15, 0/12, and 0/8 in areas VI, II, III, and IV, respectively) and a papillary thyroid carcinoma (PTC), 0.2 cm in size on the left side (numbers of lymph nodes: 2/6, 0/3, 0/10, and 0/6 in areas VI, II, III, and IV, respectively). There were no pathological changes in the MTC observed in the thyroid tissues on the left side. We believe that the follow-up of patients with both MTC and PTC should utilize a combination of the respective principles for rational disease reassessment.