Endocrine Abstracts

Introduction: Primary hyperparathyroidism, is a common endocrine disorder, but rarely related to ectopic parathyroid. Often asymptomatic, it presents a problem of localization and hence therapeutic management. We report a rare case of an ectopic thymic parathyroid adenoma.

Description: We report a case of 62-year-old women, with a history of recurrent urinary infection due to pyelocalcic lithiasis, whose etiological investigation revealed the presence of hypercalcemia. Clinically, she had polydipsia, muscle cramps and tingling of the extremities. The diagnosis was primary hyperparathyroidism (hypercalcemia 3.51 mmol/l, hypophosphatemia 0.45 mmol/l and elevated PTH 1041 ng/ml). Cervical ultrasound was normal. Parathyroid scintigraphy showed the presence of an anterior mediastinal hypermetabolic mass in the thymic lodge with a heterogeneous cystic component. CT scan showed a solid cystic mass of the anterosuperior mediastinum region, measuring 46×37×55 mm. Genetic testing was performed, and excluded genetic forms of hyperparathyroidism. Correction of hypercalcemia was based on rehydration and cincalcet hydrochloride. Thymectomy was performed by video-thoracoscopy. Anatomopathological examination concluded to an intra-thymic parathyroid adenoma. Post-operatory calcemia was normal, and PTH decreased to 84.9 ng/ml. The 3 months CT scan was normal.

Discussion: Parathyroid glands and the thymus had a common embryological origin, which explains the thymic ectopy of the parathyroid. It’s a rare entity, whose prevalence is about 16% in patients with primary hyperaldosteronism¹. The diagnosis can be evoked by persistent disorders of phosphocalcic metabolism. Cervical ultrasound and scintigraphy are first line imaging. Imaging remains an essential step in management, providing accurate cervical and mediastinal mapping enabling the surgeon to perform a targeted surgical excision, avoiding white surgical explorations. Minimally invasive radio-guided surgery, assisted with PTH measurement, improves surgical outcomes.

Reference: 1. https://pubmed.ncbi.nlm.nih.gov/23174995/#:~:text=Ectopic%20inferior%20parathyroids% 20are% 20most,tracheoesophageal%20groove% 20and%20retroesophageal%20region.