Ann Thorac Surg 1997;64:238-240
© 1997 The Society of Thoracic Surgeons
Case Report
Mediastinoscopic Extirpation of Mediastinal Ectopic Parathyroid Gland
Kiyoshi Ohno, MD,
Keiji Kuwata, MD,
Yoshio Yamasaki, MD,
Hajime Yamasaki, MD,
Nobutaka Hatanaka, MD,
Shigetaka Yamamoto, MD
Department of Surgery, Osaka Kosei-Nenkin Hospital, Osaka, Japan
Accepted for publication February 14, 1997.
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Abstract
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We report a case of a 50-year-old man with hyperparathyroidism secondary to chronic renal failure who underwent extirpation of a mediastinal ectopic parathyroid gland by a transcervical approach under mediastinoscopy. This procedure provides an excellent approach to the mediastinal ectopic parathyroid gland, and is less invasive than median sternotomy or thoracotomy.
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Introduction
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Secondary hyperparathyroidism is likely to develop in patients with chronic renal failure, and parathyroidectomy is indicated in cases resistant to vitamin D metabolite therapy. Cases of mediastinal ectopic parathyroid gland have been occasionally reported, and the gland has been extirpated by a median sternotomy or thoracotomy. We recently extirpated a mediastinal parathyroid gland by a transcervical approach using a mediastinoscope.
A 46-year-old man receiving hemodialysis due to chronic renal insufficiency underwent cervical exploration for secondary hyperparathyroidism in November 1991. Two swollen superior parathyroid glands were resected, but no inferior parathyroid gland was detected. Postoperatively, the serum parathyroid hormone-related protein-C concentration decreased from 99.3 to 26.5 ng/mL (normal, 
0.5 ng/mL), but it increased gradually, and dry cough and pain in the left leg and right shoulder appeared in 1993. Because mass shadows suspected to be enlarged parathyroid glands were noted on the caudal side of the left thyroid lobe and in the mediastinum between the common carotid and subclavian arteries and the trachea immediately above the aortic arch by thallium-201 chloride scintigraphy (Fig 1
) and computed tomographic scan (Fig 2), the patient was admitted on March 29, 1995. On admission, the serum parathyroid hormone-related protein-C level was 48.3 ng/mL.
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Fig 1. . Thallium-201 chloride scintigraphy showed abnormal uptake on the caudal side of the left thyroid lobe (T1) and in the mediastinum (T2).
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Fig 2. . Chest computed tomography showed mass shadows near the left thyroid lobe (T1) and between the common carotid and subclavian arteries and the trachea immediately above the aortic arch (T2). (P = posterior.)
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To prevent postoperative complications due to bone fragility, we extirpated the parathyroid glands by a transcervical approach under mediastinoscopic guidance on April 4. The neck was extended in the supine position, a 6-cm left collar incision was performed along the previous operative scar, the anterior cervical muscles were separated, and the thyroid gland and trachea were exposed. A yellow mass measuring 18 x 16 x 10 mm observed on the caudal side of the left thyroid lobe was extirpated. Next, the patient was placed in a head-down position, the peritracheal sheath was incised in the same surgical field, and a mediastinoscope was inserted. The trachea was dissected from the surrounding tissues to the tracheal bifurcation, and an ultrasound probe was inserted. A mass was noted immediately above the aortic arch. The fat tissue around the tumor was freed using the dissecting forceps manipulated from inside the mediastinoscope. Because the range of manipulation possible from inside the mediastinoscope was narrow, we subsequently manipulated the dissecting and grasping forceps from outside the mediastinoscope to free the tissue completely, while monitoring the operating field endoscopically. The mediastinal adipose tissue enveloping the mass was detached, and a yellow mass measuring 20 x 15 x 15 mm located between the common carotid and subclavian arteries and trachea was extirpated (Fig 3).
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Fig 3. . This intraoperative photograph shows a mass (T) located between the trachea (Tr) and the common carotid artery (C).
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The extirpated masses were both hyperplasia of parathyroid gland on histopathologic examination. The removed parathyroid gland was not used for intramuscular implantation. It was not stored frozen for future use in implantation.
The patient has followed an uneventful course after the operation, although intravenous calcium administration was needed. Ostealgia disappeared, the dry cough was alleviated, and the serum parathyroid hormone-related protein-C level decreased to 1.7 ng/mL on the ninth postoperative day.
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Comment
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Chronic renal insufficiency tends to develop into secondary hyperparathyroidism. Parathyroidectomy is indicated for secondary hyperparathyroidism that shows limited responses to oral treatment with vitamin D metabolites, and detection and extirpation of all parathyroid glands is important in this operation. However, extirpation of all parathyroid glands at the initial operation is difficult, because supernumerary and ectopic parathyroid glands are present in about 10% [1] and 5% to 20% [2] of the patients, respectively, and not all parathyroid glands are swollen. We were able to extirpate only two superior parathyroid glands at the initial operation and detected two inferior parathyroid glands near the left thyroid lobe and in the mediastinum by thallium-201 chloride scintigraphy and computed tomographic scan 3 years and 5 months after the initial operation.
About one third of ectopic inferior parathyroid glands are present in the mediastinum [3]. Of these ectopic glands, those located in the thymic tissue are reported to be removed by giving traction to the thymus via a transcervical route without sternotomy even when the glands are present 4 cm caudal to the upper sternal margin [4]. On the other hand, parathyroid glands located between the common carotid and subclavian arteries and the trachea as in our case have been extirpated by a median sternotomy or thoracotomy [5]. However, increased bone fragility is often observed in patients with secondary hyperparathyroidism, and postoperative complications associated with fracture are occasionally induced by median sternotomy or thoracotomy. A less invasive procedure such as thoracoscopic or mediastinoscopic resection therefore is preferable. In the present case, mediastinoscopic rather than thoracoscopic parathyroidectomy provided an excellent approach to the mass.
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Footnotes
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Address reprint requests to Dr Ohno, Department of Surgery, Osaka Kosei-Nenkin Hospital, Fukushima-ku, Osaka 553, Japan.
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References
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- Conn JM, Goncalves MA, Mansour KA, McGarity WC. The mediastinal parathyroid. Am Surg 1991;57:62–6.[Medline]
- Rothmund M, Diethelm L, Brünner F, Kümmerle F. Diagnosis and surgical treatment of mediastinal parathyroid tumors. Ann Surg 1976;183:139–45.[Medline]
- Àkerström G, Malmaeus J, Bergström R. Surgical anatomy of human parathyroid glands. Surgery 1984;95:14–21.[Medline]
- Wells SA, Cooper JD. Mediastinal exploration in patients with persistent hyperparathyroidism. Ann Surg 1991;214:555–61.[Medline]
- Obara T, Fujimoto Y, Tanaka R, et al. Mid-mediastinal parathyroid lesions: preoperative localization and surgical approach in two cases. Jpn J Surg 1990;20:481–6.[Medline]
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Abstract
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