A CASE OF SPORADIC MEDULLARY CARCINOMA OF THE THYROID IN WHICH SOMATIC POINT MUTATION OF RET GENE CODON 634

Abstract

A 49-year-old woman who had been pointed out having an adenomatous goiter 27 year before but let it alone was seen at the hospital, when a tumor in the center of the right thyroid lobe was confirmed. Bilateral cervical lymph nodes were palpated. Serum calcitonin and CEA levels were high and ¹²³I-MIBG scintigraphy revealed positive response. With a diagnosis of medullary carcinoma in Stage III (T3a. N1b, M0), a total thyroidectomy and conservative bilateral lymph nodes dissection of the neck were performed. Histopathological study revealed that the tumor was localized in the capsule, gave a positive reaction to calcitonin immunostaining, and was pN0 in Stage II. The tumor marker was normalized after the operation. There have been no signs of recurrence as of 7 months after the operation. On gene examinations, no germinal mutation of RET gene was noted, but mutation of MEN 2A, exon 11, and somatic point mutation of codon 634 were demonstrated. So far, this type of mutation has been though uncommon in sporadic medullary carcinomas in that this is an intriguing case.