Surgical treatment for mediastinal parathyroid adenoma causing primary hyperparathyroidism

Background: Primary hyperparathyroidism is a rare disease characterized by excessive secretion of parathyroid hormone from parathyroid adenoma, hyperplasia, or malignancy. The clinical symptoms of the condition are those of hypercalcemia. Although the lesions are commonly located in the neck region, in about 1-2 % of cases, the lesions are ectopically located within the mediastinum, where surgical excision using the cervical approach is difficult. The principal treatment of the condition is surgical excision of the lesion. However, some patients require additional surgery because of recurrence due to intraoperative dissemination. Therefore, safe and accurate excision is essential for the treatment. We reviewed the surgical treatment used at our institution for mediastinal parathyroid adenoma that caused primary hyperparathyroidism. Method: The subjects were four patients with primary hyperparathyroidism due to mediastinal parathyroid adenoma who underwent surgery at our institution within a period of 10 years, between January 2005 and December 2014. All of the patients were female, with a mean age of 64.5 years (range, 55-74 years). The examined variables included background factors, clinical condition, surgical method, and clinical outcome. Result: In all of the patients, primary hyperparathyroidism was detected with symptoms of hypercalcemia. Laboratory tests revealed a mean serum calcium level of 11.85 mg/dL (range, 11.2-13.2 mg/dL) and a mean parathyroid hormone (intact PTH) level of 304.8 pg/mL (range, 126-586 pg/mL), indicating elevated levels for all patients. Chest computed tomography (CT) revealed tumors with a mean diameter of 2.8 cm (range, 10-45 mm) in the anterior mediastinum in all of the patients. On 99mTC-methoxy isobutyl isonitrile (MIBI) scintigraphy, abnormal accumulation was observed in all of the patients. Regarding the surgical methods, median sternotomy was used for three cases and upper partial sternotomy was used for one case. The surgery was safely and accurately performed, without postoperative complications. After surgery, the serum calcium levels immediately returned to normal and the symptoms improved. Conclusion: We performed excision safely and accurately in all of the patients. In tumor identification, 99mTC-MIBI scintigraphy was useful. Accurate tumor identification and selection of the optimal surgical method are important for prevention of recurrence due to intraoperative dissemination.