ESPE Abstracts

Background: Thyroid cancer (TC) caused by germline mutations most often manifests in childhood. Hereditary forms of TC are divided into two groups: non-medullary and medullary thyroid cancer (MTC). A mutation in RET gene can be detected in about 95% of patients with MTC. If a mutation in RET gene is found, prophylactic thyroidectomy is recommended.

Aim: To demonstrate the importance of molecular genetic analysis (MGA) in the preoperative diagnosis of TC.

Methods: We performed Sanger sequencing of RET gene and whole exome sequencing by next-generation sequencing.

Case report: In December 2023 patient A., aged 13 years, was admitted with complaints of nodular goiter according to an ultrasound examination. The patient has an aggravated family history of TC. In June 2023 the patient's mother underwent thyroidectomy for MTC. Preoperative examination data of the mother: blood calcitonin - 2062 pg/mL (0-6.4). Ultrasound examination of the thyroid gland: multinodular goiter (EU-TIRADS 4). FNA biopsy of the left lobe was performed: medullary thyroid cancer (Bethesda VI), right lobe: follicular adenoma (Bethesda IV). Pathomorpholytic material

Conclusion: medullary carcinoma of the left lobe, follicular adenoma of the right lobe. The child was consulted by a pediatric endocrinologist for an increased risk of MTC due to mother’s diagnosis of MTC. Examination in December 2023: calcitonin 3.12 pg/mL (0-14.3). Ultrasound examination of the thyroid gland: a nodule in the right lobe measuring 1.1x0.5x0.7 cm (EU-TIRADS 5). An FNA biopsy was performed. Cytologic examination: clusters of large polymorphic epithelial cells that were mainly forming papillary structures with atypical changes suspicious for papillary thyroid cancer (Bethesda V) were found. MGA was performed in order to determine the scope of surgical intervention and to search for a pathogenic mutation in RET gene. MGA

Results: no pathogenic variants in the gene were identified. At this point, the child has no signs of MTC. The patient underwent surgical treatment in the volume of hemithyroidectomy. According to the pathomorphologic study: papillary microcarcinoma of the right lobe of the thyroid gland.

Conclusion: Identification of pathogenic variants in genes associated with the development of TС can significantly affect the management of patients. In our case, the presence of MTC in the mother was the reason for examination and incidental diagnosis of PTC in the child. The absence of a pathogenic mutation in RET gene ruled out the hereditary nature of the disease and determined the scope of surgical intervention. MGA is recommended not only in the presence of an aggravated heredity for thyroid cancer, but also in cases of other cancers and multinodular thyroid goiter.