Endocrine Abstracts

Introduction: The most common cause of primary hyperparathyroidism is parathyroid adenoma. Unfortunately, between 11 and 22% of these adenomas are located in ectopic positions. In this report, we describe a case diagnosed in our department with symptomatic primary hyperparathyroidism due to an ectopic parathyroid adenoma localized in thymus.

Case presentation: A 21-year-old woman was referred to our clinic for investigations, due to multiples osteoclastomas in the maxillary bones. Physical examination performed on admission revealed, in addition to the facial lesions, multiple lumps on ribs and lower limbs. Biochemical investigations confirmed primary hyperparathyroidism: hypercalcemia, hypophosphatemia and significant elevated levels of parathormone (PTH) and alkaline phosphatase. By using ultrasound examination of the neck no extrathyroidal or thyroidal masses, suggestive of a parathyroid adenoma, were detected. The patient was submitted to magnetic resonance imaging of the cervical region and mediastinum. The results revealed an enlarged thymus, which was suspected to be the site of the ectopic parathyroid adenoma. The investigations performed didn’t reveal any other clinical manifestations of hyperparathyroidism besides advanced bone lesions.

A thymectomy by using video-assisted thoracic surgery was performed in the Clinic of thoracic surgery. The pathological exam revealed a parathyroid adenoma surrounded by normal thymic tissue. Postoperatively, the plasma level of calcium and PTH decreased significantly. The patient developed hungry bone syndrome that required high amounts of oral calcium (3500 mg daily) and vitamin D for maintaining a low-normal serum calcium level.

Conclusion: This case, with an ectopic parathyroid adenoma in thymus confirmed by postoperative histology, presented advanced bone lesions, only, as clinical manifestation of hyperparathyroidism. The presentation illustrates the importance of preoperative imaging localization of parathyroid adenoma, which allows an optimal surgical approach. Mediastinal ectopic parathyroid adenoma as a cause of primary hyperparathyroidism must be always considered if cervical pathological masses are not detected.