Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) is a common endocrine disorder most commonly caused by a single adenoma of the parathyroid gland and rarely related to ectopic thymic parathyroid adenoma.

Observation: 1^st case: we report a case of a 46-year-old woman, diagnosed with PHPT. Scintigraphy concluded to a left inferior parathyroid adenoma. She underwent a focal parathyroid surgery and the adenoma was located in the thymus. The histopathology had shown an hyperplasic parathyroid tissue within a thymic parenchyma. Soon after surgery, persistent hypercalcemia up to 3mmol/l with elevated PTH level were noted. A skeletal survey showed generalized decrease in bone density. The neck ultrasonography was unremarkable as well as CT neck scan. Parathyroid scintigraphy showed a probable right inferior parathyroid adenoma. The patient was discharged with plans of a secondary surgical revision. 2^nd case: Our case is of a 66-year-old woman operated for multinodular goiter: total thyroidectomy with left parathyroidectomy of a 7 mm adenoma that was found during surgery. Two years later, hypercalcemia(3 mmol/l) hypophosphatemia(0.6mmol/l)and overtly elevated PTH level, all contributed to the diagnosis of PHPT. Scintigraphy showed a mediastinal ectopic parathyroid adenoma, cervicothoracic CT scan showed an ectopic parathyroid adenoma of 13.7 mm in the left thymic cavity. The diagnosis of a persistent PHPT related to a mediastinal ectopic parathyroid adenoma was adopted. The patient underwent, a left thymectomy surgery. Her PTH and serum calcium levels decreased significantly. No new lesions could be detected on any of the follow-up visits.

Discussion: Parathyroid glands and the thymus share a common embryological origin which could explain the presence of ectopic thymic parathyroid.