ESPE Abstracts

Introduction: Parathyroid carcinoma (PC) is a malignant neoplasm and occurs in patients with primary hyperparathyroidism (PHPT) in less than 1% of cases. There are few descriptions of PC in children in the literature. Clinical manifestations of PHPT in children are highly variable: the disease may present with dyspeptic manifestations, symptoms of intoxication, bone deformities, urolithiasis, cholelithiasis or be asymptomatic.

Materials and Methods: Molecular genetic study (next-generation sequencing) of genes: MEN1, CASR, CDC73, CDKN1A, CDKN1B, CDKN1C, CDKN2A, CDKN2C, CDKN2D, AP2S1, RET

Results: Patient, 10.5 years old. At the age of 10 years and 3 months, he complained of episodic abdominal pain. Stones were found in the left ureter and right kidney during examination. Lithotripsy was performed. Further examination revealed an increase in PTH to 211 pg/ml (N 15-60), total calcium to 3.52 mmol/l and ionized calcium to 1.7 mmol/l, phosphorus decreased to 0.96 mmol/l (N 1.2-1.8), creatinine and urea levels were within normal limits. According to the results of ultrasound examination and scintigraphy with technetium [99mTc]sestamibi with single-photon emission computed tomography, a mass of the right lower parathyroid gland measuring 9 × 8 × 13 mm was revealed. The diagnosis of PHPT was established. On examination no pathologies were revealed, height and weight are normal, no bone deformities, and no fractures in anamnesis. Hereditary history of PHPT and other tumor masses is not aggravated. Surgical removal of the right inferior parathyroid gland mass was performed. Morphologic study: parathyroid neoplasm of solid-follicular structure, consisting mainly of principal cells with moderate nuclear polymorphism, surrounded by a broad fibrous capsule with areas suspicious for invasive growth. Immunohistochemical study: tumor cells are detected in one of the venules. Parafibromin is not expressed in tumor cells, Ki67 in hot spots up to 9.5%. Reaction with antibodies to CD 34 revealed pronounced background staining of fibrous stroma. The number of mitosis figures is up to 5 in 10 fields of view. PC was diagnosed in the patient. After surgical treatment, PTH and calcium levels stabilized. According to the results of molecular genetic study, no pathogenic variants were detected. The patient is under dynamic observation.

Conclusions: PC is a rare cause of PHPT. Molecular genetic study cannot always answer the question about the cause of cancer, as it was in our case. Given the rarity of this pathology in children and clinical variability, the diagnosis of parathyroid cancer remains a challenge.

Keywords: Pediatrics, parathyroid cancer, primary hyperparathyroidism.