PMC5627225_01
Familial history of medullary thyroid carcinoma. In the maternal lineage, most family
members in each generation developed medullary thyroid carcinoma (MTC). The patient
and her mother developed MTC at the ages of eight and 32, respectively. However, the
patient's grandfather and his elderly brother, in whom the same RET
mutation was extrapolated to exist, did not develop the disease.
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Her parents were non-consanguineous Japanese individuals with a strong family history of MTC in the maternal lineage (Fig. 1).
Direct sequencing of RET. The patient and her mother were found to
have the same heterozygous mutation, C634G. Mutations in codon 634 of
RET are classified as high-risk mutations by the American Thyroid
Association guidelines; prophylactic thyroidectomy before 5-yr of age is
recommended.
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RET sequences of the patient and her mother were reanalyzed to confirm that they had the same mutation in codon 634 (Fig. 2).
Histopathological manifestations. The pathological investigation demonstrates the
presence of medullary thyroid carcinoma (MTC) in the left upper pole of the resected
thyroid. The tumor measures 0.2 cm at its largest diameter, and contains several
C-cell hyperplastic lesions. No lymph node metastasis or extra thyroidal expansion are
detected, resulting in a final diagnosis of stage I MTC. A) Hematoxylin-Eosin stain x
400: Parafollicular cells causing partial destruction of follicles. B) Calcitonin
immunostaining x 400: Tumor cells strongly reactive for calcitonin invade a thyroid
follicle.
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The pathological analysis demonstrated features of stage I MTC (Fig. 3).