Endocrine Abstracts

JOINT2571

Introduction: Parathyroid cysts are rare (0.8–3.41% of all parathyroid lesions) usually asymptomatic formations in the anterior neck region that account for 1 to 5% of neck masses in adults. Depending on the presence of hyperparathyroidism, they can be subdivided into two groups - functioning and non-functioning (approximately 90% of parathyroid cysts). However, there is a limited number of published studies focusing on pediatric cases.

Case Report: We present the case of a 16-year-old girl with a palpable, non-tender mass in the lower left quadrant of the neck. The mass was visible, asymptomatic and appearing to be located in the right thyroid lobe. The patient was referred to the clinic by a pediatric endocrinologist with a suspicion of a thyroid nodule. The patient was a healthy adolescent, with no significant history of any diseases. Her maternal grandmother had a history of goiter. Biochemical parameters, including parathyroid hormone (PTH), thyroid hormones and thyroglobulin were all within normal ranges. Ultrasound examination revealed a cystic lesion nearly completely occupying the right lobe of the thyroid gland with dimensions in the longitudinal section: 35.8/16.2 mm. A fine-needle aspiration (FNA) biopsy was performed by a more experienced adult endocrinologist, yielding 5 ml of water-clear, rapidly aspirated fluid. Following evacuation, a residual formation was observed with dimensions in the longitudinal section: 29.3/10.5 mm. Cytological analysis of the fluid showed no cellular content. However, the aspirated fluid had a markedly elevated PTH level (>2500 pg/mL, reference range: 11–87 pg/mL), confirming the parathyroid origin of the cyst. Based on expert consultation, puncture, aspiration, and sclerotherapy with ethanol were recommended one month later.

Conclusion: Non-functioning parathyroid cysts although rare present a diagnostic challenge, frequently being mistaken for thyroid pathology due to overlapping clinical and imaging characteristics. More frequent and prolonged follow-up is required due to the risk of recurrence and the potential need for surgical removal. Using additional imaging modalities such as computed tomography could be helpful, especially when surgery is chosen for a definitive treatment option. Given the rarity of this condition and the lack of clear guidelines for its diagnosis and management in pediatric patients, consultation with experienced specialists is crucial.

Key Words: parathyroid cysts, fine-needle aspiration, sclerotherapy.