Sporadic medullary thyroid carcinoma in childhood: a clinical case report

Medullary thyroid carcinoma (MTC) is one of the rarest tumors of the neuroendocrine system occurring in childhood. MTC represents approximately 4% to 8% of all thyroid malignancies in children with an incidence of 0.03 per 100,000 pediatric population per annum. As a rule, MCT in childhood is presented as part of hereditary syndromes (MEN2A, MEN2B) whereas the prevalence of the sporadic form has not been sufficiently studied as well as its molecular and genetic features. Authors represent the Russia’s first clinical case of sporadic MTC in a 16 years old child. The girl at the age of 14 y/o was examined by an endocrinologist at the place of residence due to the absence of menarche. According to the results of a comprehensive examination, a mass measuring of up to 27 mm was detected in the left lobe of the thyroid gland. Cytological examination revealed a picture suspicious for C-cell carcinoma. The basal calcitonin level was 2160 pg/ml (with 0 to 4.8 pg/ml as a norm). The patient had then underwent thyroidectomy with central lymphadenectomy as a result of histological and immunohistochemical studies of medullary thyroid carcinoma pT2N0 MxLV0Pn0. According to the results of molecular genetic study of peripheral blood, neither germinal pathogenic nor opportunistic mutations in RET gene were detected. Full-exome sequencing of DNA isolated from tumour tissue revealed as pathogenic/conditional pathogenic mutations RET p.M918T, CHEK2 p. R29X, VRK1 p.H119R and ARSE p. G422R. After 3.5 years of follow-up, the patient had a complete structural and biochemical remission of the disease.