Ann Thorac Surg 2001;72:1758-1760
© 2001 The Society of Thoracic Surgeons
Case report
Intraoperative radioguided thoracoscopic removal of ectopic parathyroid adenoma
Michael C. Ott, MSca,
Richard A. Malthaner, MD*a,
Robert Reid, MDb
a Division of Thoracic Surgery, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada
b Department of Nuclear Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada
Accepted for publication January 19, 2001.
* Address reprint requests to Dr Malthaner, Division of Thoracic Surgery, London Health Sciences Centre, 375 South St, N345, London, Ontario, Canada N6A 4G5
e-mail: richard.malthaner{at}lhsc.on.ca
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Abstract
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Twenty-five percent of primary hyperparathyroidism is caused by ectopic mediastinal parathyroid glands, with 2% of these not accessible to standard cervical surgical approaches. Advancement in video-assisted thoracoscopic surgical techniques has decreased the need for sternotomy to successfully remove these ectopic glands. The thoracoscopic approach, however, is limited by the surgeon’s inability to always accurately visualize ectopic glands. Intraoperative radionuclide-guided dissection, using a thoracoscopic approach, provides a novel adjunct to the removal of occult ectopic parathyroid glands. We report a case of an occult ectopic parathyroid adenoma removed thoracoscopically using an intraoperative handheld gamma probe.
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Introduction
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Primary hyperparathyroidism is the leading cause of hypercalcemia in North America and is second only to malignancies as the cause of hypercalcemia in hospitalized patients. Eighty-five percent of all primary hyperparathyroidism is caused by parathyroid adenomas, whereas parathyroid hyperplasia and parathyroid carcinoma account for 15% and less than 1%, respectively. We report a patient who underwent an intraoperative radionuclide-guided thoracoscopic resection of an occult mediastinal ectopic parathyroid adenoma.
The patient was a 52-year-old woman with a past medical history that included a tonsillectomy, tubal ligation, appendectomy, hysterectomy, and cholecystectomy. As part of a routine yearly physical, her primary care physician ordered a bone mineral density scan that revealed advanced osteoporosis. During investigation of her osteoporosis, her serum calcium was elevated at 2.99 mmol/L (high normal, 2.62 mmol/L) and parathyroid hormone was also elevated at 28.4 pmol/L (high normal, 6.8 pmol/L). The patient was referred to a head and neck surgeon and underwent a bilateral neck, parathyroid, and limited superior mediastinal exploration. Three normal parathyroid glands were found. The left lower gland could not be identified. Postoperatively she remained hypercalcemic and was found to be persistently hyperparathyroid. Venous parathyroid hormone sampling was done and could not identify a clear source. A computed tomographic scan was equivocal. Magnetic resonance imaging and technetium-99m pertechnetate methoxy-isobutyl-isonitrite (99m-Tc MIBI) nuclear localization (Fig 1) suggested a focal abnormality in the anterior mediastinum.
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Fig 1. Preoperative 99m-Tc MIBI nuclear scan revealing a focus of increased uptake anteriorly in the left superior mediastinum (arrow).
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After normal intraoperative bronchoscopy, the patient was placed in the right lateral decubitus position and intubated with a double-lumen endotracheal tube for single lung ventilation. Before starting the operative procedure, the patient was injected with 20 Mbq of 99m-Tc MIBI. A thoracoscopic exploration using three 12-mm thoraco-ports was performed, but no abnormal tissue could be detected in the anterior mediastinum. The handheld gamma scintillation probe (Navigator Gamma Guidance System, AutoSuture, US Surgical, St. Laurent, QC, Canada) was then introduced through a thoraco-port in a sterile fashion and used to localize an area of increased 99m-Tc MIBI uptake within the left anterior mediastinum, anterior to the main pulmonary artery. This tissue was dissected out and was confirmed by pathologic frozen section to contain parathyroid tissue.
A repeat 99m-Tc MIBI scan done on postoperative day 1 confirmed that the area of abnormal uptake seen preoperatively in the anterior mediastinum was now absent (Fig 2). The patient’s serum calcium normalized at levels of 2.29 to 2.42 mmol/L and she was discharged without complications on postoperative day 5. The final pathology confirmed a 1-cm parathyroid adenoma. The 1-month follow-up revealed no complications and a serum calcium level remaining in the normal range.
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Comment
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The most common cause for persistent hyperparathyroidism post neck exploration is an occult solitary ectopic adenoma. It has been estimated that 11% to 25% of all patients with primary hyperthyroidism have ectopic mediastinal hyperfunctioning parathyroid tissue [1]. However, only 2% of ectopic parathyroid locations are not accessible through standard cervical excision.
The available preoperative localization methods of ultrasound, computed tomography, and magnetic resonance imaging have a diagnostic accuracy of 57% to 68% dependent on size and location of the pathologic parathyroid tissue. Radionuclide localization has been used because of the limitations with conventional imaging modalities. Radio-guided parathyroidectomy using handheld gamma counters during cervical exploration has been reported [2]. This technique allows more accurate unilateral neck explorations, decreased operative time, decreased morbidity, and better patient care.
The most challenging aspect of parathyroid operation remains those individuals with hyperfunctioning mediastinal parathyroid tissue that is not accessible through cervical incisions. Previously, such patients would have had a sternotomy with mediastinal exploration. Two techniques have evolved to avoid sternotomy and mediastinal exploration for ectopic parathyroid tissue. Angiographic ablation appears to decrease morbidity and negate the requirement for operation. This procedure, however, has a failure rate of 40%. The second technique uses video-assisted thoracoscopic surgery (VATS). There are several reports in the literature of successful resections of ectopic parathyroid tissue using VATS [3–6]. In one small series of patients with VATS for mediastinal ectopic parathyroid tissue, the only complication reported was intercostal neuralgia (seen in 1 of 7 patients) [3]. Sternotomy for removal of ectopic parathyroid tissue has a 19% to 21% complication rate including pulmonary complications (effusions, pneumonitis, and pneumothorax), wound complications, deep venous thrombosis, and atrial fibrillation [3, 6]. The VATS also demonstrated decreased number of hospital days when compared to conventional sternotomy [3].
The success of VATS depends on accurate localization before operation, with little use of intraoperative localization other than direct visualization. The successful resection of ectopic parathyroid tissue using VATS is limited by the visual distinctness of the ectopic tissue in comparison to surrounding structures. With smaller parathyroid adenomas, it may be visually difficult to separate normal from abnormal tissue, making complete surgical resections difficult. In this patient we combined VATS with intraoperative radionuclide-guided dissection for a small adenoma that could not be seen with the thoracoscope. The handheld gamma scintillation probe aided in the localization and dissection of the adenoma. The probe is readily available at centers already performing sentinel node biopsies for cancer. This novel approach takes advantage of both the minimal invasiveness of VATS and the increased accuracy of radionuclide-guided dissection and resection. We believe that radionuclide-guided dissection with VATS reduces unnecessary dissection and may decrease operative time and risk.
In conclusion, the intraoperative radionuclide-guided dissection through a thoracoscopic approach was used to successfully resect an occult ectopic mediastinal parathyroid adenoma. This technique provides a distinct advantage over conventional VATS when ectopic parathyroid tissue is not easily visualized.
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References
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Medrano C., Hazelrigg S.R., Landreneau R.J., Boley T.M., Shwago R.N., Grasch A. Thoracoscopic ressection of ectopic parathyroid glands. Ann Thorac Surg 2000;69:221-223.[Abstract/Free Full Text]
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Dackiw A.P.B., Sussman J.J., Fritsche H.A., et al. Relative contributions of technetium Tc 99m sestambi scintigraphy, intraoperative gamma probe detection, and the rapid parathyroid hormone assay to the surgical management of hyperparathyroidism. Arch Surg 2000;135:550-557.[Abstract/Free Full Text]
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Medrano C., Hazelrigg S.R., Landreneau R.J., Boley T.M., Shwago R.N., Grasch A. Thoracoscopic ressection of ectopic parathyroid glands. Ann Thorac Surg 2000;69:221-223.
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Smythe W.R., Bavaria J.E., Hall R.A., Kline G.M., Kaiser L.R. Thoracoscopic removal of mediastinal parathyroid adenoma. Ann Thorac Surg 1995;59:236-238.[Abstract/Free Full Text]
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Furrer M., Leutenegger A.F., Ruedi T.H. Thoracoscopic resection of an ectopic giant parathyroid adenoma: indication, technique and three year follow-up. Thorac Cardiovac Surgeon 1996;44:208-209.
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Prinz R.A., Lonchyna V., Carnaille B., Wurtz A., Proye C. Thoracoscopic excision of enlarged mediastinal parathyroid glands. Surgery 1994;116:999-1005.[Medline]
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Abstract
Introduction
