[Genetic testing for ret mutation for early diagnosis and treatment in familial medullary thyroid carcinoma: a case...

A 13-year-old girl and her older sister were referred to our hospital because her father and another older sister and been suffering from medullary thyroid carcinoma (MTC). Physical examinations revealed no thyroid mass. Ultrasonography (US) detected a small hypoechoic lesion in the right thyroid lobe, 3 mm in size. The serum calcitonin level was slightly elevated for their age. One and half year later, US finding showed a slightly larger mass, 7 mm in size, which was not palpable. Genetic testing for ret protooncogene mutation revealed a point mutation at codon 634 (Cys-->Arg) in exon 11. Surgical treatment was recommended, however, the patient wanted to receive it only after the admission to senior high school. Her sister had no mutation in ret protooncogene. The patient underwent total thyroidectomy with modified neck dissection at 16 years of age. At that time, a new mass emerged in the left thyroid lobe and the serum calcitonin level increased to 171 pg/ml. MTC was found in each lobe with positive staining of CEA and carcitonin. No lymph node metasis was found. Her postoperative course was uneventful. Genetic testing for ret mutation is effective for early diagnosis and treatment of patient with FMTC, and is recommended as standard management for hereditary MTC in affected families.