Surgery for Ectopic Parathyroid Adenoma in Lower Part of Superior Mediastinum through a Transcervical Incision

摘要

INTRODUCTION Ectopically located hyperfunctioning parathyroid gland(s) are responsible for approximately 6–16% of hyperparathyroidism cases, in which about 6% can be ascribed to ectopic growth in the mediastinal site.[1] Treatment of ectopic adenomas usually requires resection. There are various techniques to resect ectopic parathyroid glands, which are mainly depended on the ectopic gland's location. However, choosing the correct type of treatment for cases can be difficult since there are no commonly accepted guidelines for treatment selection. Here, we reported a male patient, whose imaging studies revealed an ectopic parathyroid gland, located in the lower part of the superior mediastinum, below the innominate vein. We performed parathyroidectomy, through a traditional transcervical incision, avoiding more invasive procedures and reducing the cost of treatment. CASE REPORT A 58-year-old native Chinese man was presented with nephrolithiasis, his serological tests demonstrated explicit hyperparathyroidism with parathormone levels dramatically elevated to 314.80 pg/ml (reference value: 15.00–65.00 pg/ml) and calcium concentration increased to 3.23 mmol/L (reference value: 2.10–2.60 mmol/L). A 24-h urine collection revealed high levels of urinary calcium at 11.50 mmol/24 h (reference value: 2.50–7.50 mmol/24 h); meanwhile, the bone mineral density test results (Z = −2.96, T = −3.69) showed that the patient had osteoporosis. Altogether, the tests indicated high-functioning parathyroid. Therefore, to locate the parathyroid gland(s) and identify any abnormalities, we applied several imaging techniques, including cervical ultrasound, contrast computed tomography (CT) of the neck and chest [Figure 1a], and 99mTc-Sestamibi scan. The combination of radionuclide tomography and CT scan revealed a soft-tissue density mass, which was located inferior to the innominate vein and the aortic arch in the superior mediastinum [Figure 1b]. Another nodule, located posterior to the right lobe of thyroid, was also detected by ultrasound and CT.Figure 1: Preoperative imaging and intraoperative photograph. (a) The axial computed tomography indicated an abnormal mass in the lower part of superior mediastinum. (b) The ectopic parathyroid adenoma was demonstrated through the fusion imaging of radionuclide tomography and computed tomography scan. (c) The ectopic parathyroid adenoma was exposed to the cervical incision by dragging with thymus and separating surrounding tissue. All the arrows were point to the ectopic parathyroid adenoma.An ectopic parathyroidectomy was then performed with a traditional transcervical collar incision. When the space between the ascending aorta and sternum, inferior to the left innominate vein, was exposed, an abnormal mass, just left to the confluence of bilateral innominate vein, was identified. The location of the mass was in agreement with the location identified by the preoperative scans. Following, the mass was “dragged” out with the thymus, through the cervical incision, by gradually separating it from the surrounding normal tissues [Figure 1c]. The nodule posterior to the right lobe of the thyroid was excised simultaneously. Later on, pathological examination identified the masses as parathyroid adenoma (retrosternal mass) and parathyroid cyst (nodule posterior to the right lobe of thyroid). Postoperative serology tests showed that the patient's calcium, phosphate, and parathormone levels were greatly reduced (2.55 mmol/L, 0.57 mmol/L, and 5.90 pg/ml, respectively) on the 1st day. DISCUSSION When the position of ectopic mediastinal parathyroid glands is deeper, parathyroidectomy through conventional cervical incision is more difficult to perform. Conventionally, deeply located parathyroid glands required a median sternotomy. However, due to their significant complications, nowadays, these techniques are only used as alternative procedures. In recent years, advanced technologies such as video-assisted thoracoscopic s