Ectopic mediastinal parathyroid adenoma resected by video-assisted thoracoscopic surgery

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(1)332. CASE REPORT. Ectopic Mediastinal Parathyroid Adenoma Resected by Video-Assisted Thoracoscopic Surgery 1. Nan-Yung Hsu, Chia-Ling Chang, Shung-Shung Sun , Chih-Shiun Shih, Ping-Ru Chen 1. Division of Chest Surgery, Department of Surgery and Department of Nuclear Medicine, China Medical University Hospital, Taichung, Taiwan, R.O.C.. Ectopic mediastinal parathyroid adenoma (EMPA) is not accessible by standard cervical surgical approaches. Although sternotomy is a common procedure for resecting EMPA, videoassisted thoracoscopic surgery (VATS) is a safe and effective alternative which produces aesthetically acceptable results. We describe a case of a 55-year-old woman on dialysis with chronic renal failure and persistent hyperparathyroidism resulting from an EMPA which was removed successfully by VATS. ( Mid Taiwan J Med 2003;8:332-5). Key words ectopic mediastinal parathyroid adenoma, hyperparathyroidism, video-assisted thoracoscopic surgery. INTRODUCTION. Five to fifteen percent of patients on dialysis with renal hyperparathyroidism develop complications and require surgical intervention [1]. Bone pain, skin itching, and soft tissue calcification are indications for surgery [2]. Ectopic parathyroid adenoma is a frequent cause of persistent or recurrent hyperparathyroidism after parathyroidectomy in patients with chronic renal failure on dialysis [3,4]. Recent improvements in diagnostic imaging such as 99mTc-methoxyisobutylisonitrile (MIBI), have allowed ectopic parathyroid adenoma in the mediastinum to be identified preoperatively [5]. With video-assisted thoracoscopic surgery (VATS), ectopic mediastinal parathyroid adenoma (EMPA) can be excised successfully by the Received : August 11, 2003. Revised : November 15, 2003. Accepted : November 18, 2003. Address reprint requests to : Nan-Yung Hsu, Division of Chest Surgery, Department of Surgery, China Medical University Hospital, 2 Yuh-Der Road, Taichung 404, Taiwan, R.O.C.. shortest possible route without the need for sternotomy [6-9]. We report a case of a 55-yearold woman on dialysis with chronic renal failure, persistent hyperparathyroidism, and symptoms of progressive renal osteodystrophy. MIBI scintigraphy and chest CT detected EMPA on the right side of the anterior mediastinum. The adenoma was resected successfully by VATS. Her serum parathyroid hormone level returned to normal and she recovered well. The patient has been free of symptoms and signs of hyperparathyroidism during 3 years of follow-up. CASE REPORT. A 55-year-old female patient with a history of end stage renal disease on maintenance hemodialysis for 8 years had diffuse bone pain on admission to this hospital. Her serum calcium was 3.38 mmol/L (high normal, 2.83 mmol/L) and her parathyroid hormone was 334.72 pg/mL (high normal, 54 pg/mL). Chest CT revealed an enhanced 2 cm 2 cm nodule on the right upper.

(2) Nan-Yung Hsu, et al.. 333. Fig. 1. Chest CT reveals an enhanced 2 cm 2 cm nodule in the right superior anterior mediastinum (arrow).. Fig. 2. 99mTc MIBI parathyroid scan demonstrates persistent focal increased tracer uptake in the right superior mediastinum (arrow).. superior mediastinum (Fig. 1). Subsequent MIBI parathyroid scan demonstrated persistent focal increased tracer uptake in the right superior mediastinum (Fig. 2). EMPA was diagnosed and VATS was performed via the right side. A doublelumen endotracheal tube was inserted and the patient was placed in a posterolateral thoracotomy position under general anesthesia. Four trocar sites were used, and all were performed by a standard 10-mm rigid thoracoscope with a 0 degree angle. The well-defined 2 cm 2 cm nodule located on the superior mediastinum near the superior vena cava and the right lobe of the thymus was resected by standard thoracoscopic instrumentation. Pathological examination of a frozen nodule section confirmed parathyroid adenoma. The operation lasted 90 min. The postoperative course was uneventful, and postoperative calcium concentrations and parathyroid hormone levels returned to normal. She was discharged from our hospital on the seventh postoperative day. The patient has been well and free of symptoms and signs of hyperparathyroidism during 3 years of follow-up.. are as high as 20% [10], ectopic parathyroid adenoma can exist as secondary hyperparathyroidism in patients with chronic renal failure on dialysis [3,4]. CT is reliable for detecting parathyroid glands larger than 1.5 cm; however, the procedure is less capable of identifying smaller glands. The 99m Tc-MIBI scan, on the other hand, offers an 86% success rate at detecting tumors greater than 1 g, and a 100% success rate at tumors larger than 2 g [9]. Embryologically, the inferior parathyroid glands originate from the third bronchial pouch with the thymus, which may explain why most ectopic parathyroid glands are found in close proximity to the thymus gland. Microscopically, thymic tissue in fat was disclosed on its capsule in this study. It was reported by Medrano et al that four of seven ectopic parathyroid glands were intrathymic and the remaining three, parathymic in location [9]. Many surgical methods for resecting EMPA have been reported in the literature, including medial sternotomy [11,12], partial sternotomy [3], subxiphoid video-mediastinoscopy [13], and VATS [6-9]. However, the VATS approach results in fewer postoperative complications. For example, only 1 in 7 patients (14%) suffered minor complications in a report by Medrano et al [9], while the complication rate associated with sternotomy was 19% according to Conn et al [11],. DISCUSSION. The incidence of patients on dialysis who develop various musculoskeletal complications has been increasing [3]. Although 90% of hyperparathyroidism is primary and estimates of the prevalence of mediastinal parathyroid glands.

(3) 334. Ectopic Parathyroid Adenoma. and 21% as reported by Russell et al [12]. The VATS approach also leaves fewer surgical wounds than other surgical methods. The subxiphoid approach may be suitable for biopsy procedures; however, it requires placement of additional ports if instruments are needed for resection. Hence the subxiphoid approach would not seem to offer any significant advantages over the VATS approach as it was reported in the literature [6-9] and in this study. REFERENCES. 1. Rothmund M, Wagner PK. Total parathyroidectomy and autotransplantation of parathyroid tissue for renal hyperparathyroidism. A one- to six-year follow-up. Ann Surg 1983;197:7-16. 2. Chou FF, Lee CH, Lee CT. Muscle force and bone mineral density after parathyroidectomy and subcutaneous autotransplantation for secondary hyperparathyroidism. World J Surg 1999;23:452-7. 3. Kao CL, Chou FF, Chang JP. Minimal invasive surgery for resection of parathyroid tumor in the aortopulmonary window. J Cardiovasc Surg (Torino) 2003;44:139-40. 4. Marakovic J, Biocina B, Sutlic Z, et al. Surgical treatment of mediastinal parathyroid adenoma. Acta Med Croatica 2002;56:65-8. 5. Ipponsugi S, Takamori S, Suga K, et al. Mediastinal parathyroid adenoma detected by 99mTc-. methoxyisobutylisonitrile: report of a case. Surg Today 1997;27:80-3. 6. Ott MC, Malthaner RA, Reid R. Intraoperative radioguided thoracoscopic removal of ectopic parathyroid adenoma. Ann Thorac Surg 2001;72: 1758-60. 7. Prinz RA, Lonchyna V, Carnaille B, et al. Thoracoscopic excision of enlarged mediastinal parathyroid glands. Surgery 1994;116:999-1005. 8. Furrer M, Leutenegger AF, Ruedi T. Thoracoscopic resection of an ectopic giant parathyroid adenoma: indication, technique, and three years follow-up. Thorac Cardiovasc Surg 1996;44:208-9. 9. Medrano C, Hazelrigg SR, Landreneau RJ, et al. Thoracoscopic resection of ectopic parathyroid glands. Ann Thorac Surg 2000;69:221-3. 10.Soler R, Bargiela A, Cordido F, et al. MRI of mediastinal parathyroid cystic adenoma causing hyperparathyroidism. J Comput Assist Tomogr 1996; 20:166-8. 11. Conn JM, Goncalves MA, Mansour KA, et al. The mediastinal parathyroid. Am Surg 1991;57:62-6. 12. Russell CF, Edis AJ, Scholz DA, et al. Mediastinal parathyroid tumors: experience with 38 tumors requiring mediastinotomy for removal. Ann Surg 1981;193:805-6. 13.Hutter J, Junger W, Miller K, et al. Subxiphoidal videomediastinoscopy for diagnostic access to the anterior mediastinum. Ann Thorac Surg 1998;66: 1427-8..

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