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Radioisotope-navigated video-assisted thoracoscopic operation for ectopic mediastinal parathyroid
Case report Radioisotope-navigated video-assisted thoracoscopic operation for ectopic mediastinal parathyroid Naoyoshi Onoda, MD, PhD, Tetsuro Ishikawa, MD, PhD, Nobuya Yamada, MD, PhD, Terue Okamura, MD, PhD, Hideki Tahara, MD, PhD, Masaaki Inaba, MD, PhD, Tsutomu Takashima, MD, Yoji Sakate, MD, and Kosei Hirakawa-YS Chung, MD, PhD, Osaka, Japan
From the Department of Surgical Oncology, Department of Oncology, Department of Radiology, and Department of Metabolism, Endocrinology and Molecular Medicine; Osaka City University Graduate School of Medicine, Osaka, Japan
ECTOPIC PARATHYROID ADENOMA in the mediastinum has been found in a small percentage of hyperparathyroidism cases. Conventional surgical approaches to these mediastinal lesions, such as sternotomy or thoracotomy, are major, invasive procedures. Recently, thoracoscopic operations of the mediastinal parathyroid gland have been used as an alternative, minimally invasive approach.1,2 Still, sometimes we have experienced difficulty in intraoperatively identifying the small lesion underneath the mediastinal pleura using the thoracoscopic view. 99m technetium-methoxyisobutylisonitrile (Tc-MIBI) scintigraphy is reported to be a reliable tool for identifying the location of the hyperplastic parathyroid gland. Moreover, intraoperative radioisotope (RI)-navigation using a handheld gamma counter was reported to be advantageous for finding the lesion during neck exploration.3,4 Herein, we report a case of a mediastinal parathyroid tumor that was removed successfully and safely with an RI-navigated, minimally invasive thoracoscopic operation, and we discuss the usefulness of and indications for this procedure. CASE REPORT A 58-year-old woman was referred to our hospital for further examination of a recurrent elevation of the Reprint requests: Naoyoshi Onoda, MD, PhD, Department of Oncology, Institute of Geriatrics and Medical Science, Osaka City University Graduate School of Medicine, 1-4-3, Asahimachi, Abeno-ku, Osaka 545-8585, Japan. Surgery 2002;132:17-9. Copyright 2002, Mosby, Inc. All rights reserved. 0039-6060/2002/$35.00 + 0 11/57/125172 doi:10.1067/msy.2002.125172
serum parathyroid hormone after parathyroidectomy. She was introduced to hemodialysis in 1983. Surgical removal of the 4 hyperplastic parathyroid glands and autotransplantation on her left arm were performed in 1994. In 1997, she started to feel bone pain in her spine, and a compression fracture of the thoracic spine bone was found. The serum calcium and parathyroid hormone levels were gradually elevated. She was then referred to our hospital. On physical examination, she was found to have severe kyphosis of her thoracic spine. On blood examination, marked elevations of her serum intact-parathyroid hormone levels (1282.0 pg/mL) (normal range: 74 to 273) and alkaline phosphatase level (567 IU/L) were found. Her serum calcium levels (9.6 mg/dL) and phosphate level (7.3 mg/dL) had been corrected. Magnetic resonance imaging showed a small round mass of 1.5 cm in diameter in the upper mediastinal area of the aortic arch (Fig 1, A). 99mTcMIBI scintigraphy demonstrated a small hot spot of RI accumulation in her upper mediastinum at 15 minutes (Fig 1, B) and 120 minutes after a radiotracer (600 MBq) intravenous injection. Surgical removal of the mediastinal tumor with the thoracoscopic minimally invasive technique was planned.1,2 Although the lesion was displayed by several imaging techniques, we recognized that identifying the tumor could be difficult because of the severe deformity of her thorax and the displacement of mediastinal structures. Thus, intraoperative RI-navigation was conducted by using 99mTc-MIBI and a handheld gamma probe. 99mTc-MIBI (300 MBq = 0.3 mCi/kg)3 was injected, and the early phase image obtained 15 minutes later was similar to the image taken before. The patient was then transferred to the operation room and was fixed in a right lateral position under general anesthesia. A 10-mm port was placed in the 6th intercostal space, and thoracoscopy was performed 2 hours after 99mTc-MIBI injection. No tumorous lesion could be found by a video view alone. A second 5-mm port was then placed in the 7th intercostal space for a thin scope (5-mm diameter), and a gamma probe SURGERY 17
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A
A
B
B Fig 1. Preoperative imaging of ectopic parathyroid adenoma. A, Magnetic resonance imaging demonstrated possible small, low-intensity mass (arrows) in anterior-upper mediastinum on aortic arch. Marked deformity of thoracic cavity was noted. B, 99mTc-MIBI scintigraphy demonstrated small hot spot in upper mediastinum. No accumulation was found in neck. (Navigator GPS and thoraco-probe; United States Surgical, Norwalk, Conn) was inserted through the first 10-mm port. Radioactivity was surveyed by contacting the tip to the mediastinal pleura. As shown in Fig 2, A, approximately 2-fold activity was demonstrated at a spot approximately 2 cm in diameter in the upper mediastinum. A third 5-mm port was then placed in the 3rd intercostal space for the second forceps, and a 2-cm-long incision was made on the mediastinal pleura on the spot detected by the probe. A round tumor of 1.5 cm in diameter was found just beneath the pleura (Fig 2, B). No invasive growth was found around the tumor, and the tumor was removed with a few grams of blood loss. The entire operation time was 50 minutes, and the time needed for RI-navigation was only 5 minutes. The resected tumor was 1.5 1.5 1.2 cm and weighed 2.1 g. The tumor was round with a thin capsule. Microscopically,
Fig 2. Representative views of video-assisted thoracoscopy are shown. A, No tumorous lesion was found by simple thoracoscopic examination. Radioactivity per 1 second is indicated on referenced areas, showing approximately 2fold activity at point where ectopic parathyroid adenoma was located. B, Intraoperative thoracoscopic view of ectopic parathyroid gland (arrow) located underneath mediastinal pleura. the tumor was composed of chief cells with round nuclei and clear cytoplasm without cell atypia and was diagnosed as an ectopic hyperplastic parathyroid gland. On the 14th day, the patient went without event back to her local hospital to continue hemodialysis, supplemented with alfacalcidol (2 µg) and calcium lactate (6 g). The serum levels of parathyroid hormone and calcium were decreased to 41 pg/mL and 6.2 mg/dL, respectively, on the 7th day. No symptoms suggesting hypoparathyroidism or hyperparathyroidism have been found up to this time.
DISCUSSION Ectopic parathyroid swelling with hyperparathyroidism is often found, as in our case, in patients with chronic renal failure, known as compromised hosts. Thus, to apply minimally invasive video-assisted thoracoscopic surgery (VATS)1,2 in these cases is considered reasonable and suitable. As Prinz et al1 stated, the location of the lesion should be evaluat-
Onoda et al 19
Surgery Volume 132, Number 1 ed precisely before the operation. However, lesions are often hidden beneath the pleura or located between the mediastinal structures. Moreover, a fine sense of touch is not available in VATS, so sometimes it is difficult to find the small lesions located beyond the mediastinal pleura, especially in cases with a deformed thorax, such as ours. We have already applied VATS in 4 cases of ectopic mediastinal parathyroid gland, and in those, it took 30 to 60 minutes to identify the lesion intraoperatively even if the location had been precisely identified preoperatively in relation to the other normal visible structures. To overcome this difficulty, shorten the operation time, and reduce the stress to the surgeon, we combined the RI-navigation method with VATS to identify underlying small lesions. Preoperative RI detection and intraoperative navigation with 99mTc MIBI is a very elegant tool for pointing out the responsive lesion in the parathyroid operation, and the reliability of the method has already been reported.3,4 The mean emitted radioactivity of the parathyroid adenoma in the neck was reported to be 32% higher than that of the background neck emission.3 In our case, we observed radioactivity at the point of the hyperplastic gland that was more than double that of the background neck emission. As shown in Fig 1, B, the background radioactive emission in the mediastinum was similar to that in the neck. High background radioactivity is unavoidable in the neck, even when a probe with very strict directional resolution is used, because of 99mTc-MIBI accumulation in the thyroid gland. However, we were able to flame off the background radioactivity of the heart in VATS by directing the probe so as not to point at the heart while it was surveying.
Clear 99mTc-MIBI accumulation in the lesion and clear thoracic space without adhesion was necessary for this technique to be applied. The indications for the use of this technique might be limited because of the cost, risk of radiation exposure, and necessity for intimate cooperation between the surgeon, radiologist, and respective staffs of the dialysis room and operation room. Furthermore, most lesions can be identified precisely only from the video view. However, by using the navigation technique to identify the ectopic parathyroid hidden beneath the pleura, we could minimize not only the time, but also the unnecessary wound in the mediastinum. Moreover, the stress imposed on the surgeon by searching for the lesion and confirming its complete removal is far lower when this technique is used. This RI-navigated VATS is likely to be one of the most reliable and safe methods for removing ectopic parathyroid in the mediastinum. We believe that this technique will contribute to better prognoses for patients with hyperparathyroidism by reducing the operative complications and expanding the surgical indications. REFERENCES 1. Prinz RA, Lonchyna V, Carnaille B, Wurtz A, Proye C. Thoracoscopic excision of enlarged mediastinal parathyroid glands. Surgery 1994;116:999-1005. 2. Ishikawa T, Nishimura S, Michigami S, Nishiguchi Y, Yoshikawa K, Nagayama M, et al. Thoracoscopic excision of mediastinal parathyroid tumor. Final program and abstracts. SAGES 1997;74. 3. Norman J, Chheda H. Minimally invasive parathyroidectomy facilitated by intraoperative nuclear mapping. Surgery 1997;122:998-1004. 4. Norman J, Denham D. Minimally invasive radioguided parathyroidectomy in the reoperative neck. Surgery 1998;124:1088-93.
From the Department of Surgical Oncology, Department of Oncology, Department of Radiology, and Department of Metabolism, Endocrinology and Molecular Medicine; Osaka City University Graduate School of Medicine, Osaka, Japan
ECTOPIC PARATHYROID ADENOMA in the mediastinum has been found in a small percentage of hyperparathyroidism cases. Conventional surgical approaches to these mediastinal lesions, such as sternotomy or thoracotomy, are major, invasive procedures. Recently, thoracoscopic operations of the mediastinal parathyroid gland have been used as an alternative, minimally invasive approach.1,2 Still, sometimes we have experienced difficulty in intraoperatively identifying the small lesion underneath the mediastinal pleura using the thoracoscopic view. 99m technetium-methoxyisobutylisonitrile (Tc-MIBI) scintigraphy is reported to be a reliable tool for identifying the location of the hyperplastic parathyroid gland. Moreover, intraoperative radioisotope (RI)-navigation using a handheld gamma counter was reported to be advantageous for finding the lesion during neck exploration.3,4 Herein, we report a case of a mediastinal parathyroid tumor that was removed successfully and safely with an RI-navigated, minimally invasive thoracoscopic operation, and we discuss the usefulness of and indications for this procedure. CASE REPORT A 58-year-old woman was referred to our hospital for further examination of a recurrent elevation of the Reprint requests: Naoyoshi Onoda, MD, PhD, Department of Oncology, Institute of Geriatrics and Medical Science, Osaka City University Graduate School of Medicine, 1-4-3, Asahimachi, Abeno-ku, Osaka 545-8585, Japan. Surgery 2002;132:17-9. Copyright 2002, Mosby, Inc. All rights reserved. 0039-6060/2002/$35.00 + 0 11/57/125172 doi:10.1067/msy.2002.125172
serum parathyroid hormone after parathyroidectomy. She was introduced to hemodialysis in 1983. Surgical removal of the 4 hyperplastic parathyroid glands and autotransplantation on her left arm were performed in 1994. In 1997, she started to feel bone pain in her spine, and a compression fracture of the thoracic spine bone was found. The serum calcium and parathyroid hormone levels were gradually elevated. She was then referred to our hospital. On physical examination, she was found to have severe kyphosis of her thoracic spine. On blood examination, marked elevations of her serum intact-parathyroid hormone levels (1282.0 pg/mL) (normal range: 74 to 273) and alkaline phosphatase level (567 IU/L) were found. Her serum calcium levels (9.6 mg/dL) and phosphate level (7.3 mg/dL) had been corrected. Magnetic resonance imaging showed a small round mass of 1.5 cm in diameter in the upper mediastinal area of the aortic arch (Fig 1, A). 99mTcMIBI scintigraphy demonstrated a small hot spot of RI accumulation in her upper mediastinum at 15 minutes (Fig 1, B) and 120 minutes after a radiotracer (600 MBq) intravenous injection. Surgical removal of the mediastinal tumor with the thoracoscopic minimally invasive technique was planned.1,2 Although the lesion was displayed by several imaging techniques, we recognized that identifying the tumor could be difficult because of the severe deformity of her thorax and the displacement of mediastinal structures. Thus, intraoperative RI-navigation was conducted by using 99mTc-MIBI and a handheld gamma probe. 99mTc-MIBI (300 MBq = 0.3 mCi/kg)3 was injected, and the early phase image obtained 15 minutes later was similar to the image taken before. The patient was then transferred to the operation room and was fixed in a right lateral position under general anesthesia. A 10-mm port was placed in the 6th intercostal space, and thoracoscopy was performed 2 hours after 99mTc-MIBI injection. No tumorous lesion could be found by a video view alone. A second 5-mm port was then placed in the 7th intercostal space for a thin scope (5-mm diameter), and a gamma probe SURGERY 17
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A
A
B
B Fig 1. Preoperative imaging of ectopic parathyroid adenoma. A, Magnetic resonance imaging demonstrated possible small, low-intensity mass (arrows) in anterior-upper mediastinum on aortic arch. Marked deformity of thoracic cavity was noted. B, 99mTc-MIBI scintigraphy demonstrated small hot spot in upper mediastinum. No accumulation was found in neck. (Navigator GPS and thoraco-probe; United States Surgical, Norwalk, Conn) was inserted through the first 10-mm port. Radioactivity was surveyed by contacting the tip to the mediastinal pleura. As shown in Fig 2, A, approximately 2-fold activity was demonstrated at a spot approximately 2 cm in diameter in the upper mediastinum. A third 5-mm port was then placed in the 3rd intercostal space for the second forceps, and a 2-cm-long incision was made on the mediastinal pleura on the spot detected by the probe. A round tumor of 1.5 cm in diameter was found just beneath the pleura (Fig 2, B). No invasive growth was found around the tumor, and the tumor was removed with a few grams of blood loss. The entire operation time was 50 minutes, and the time needed for RI-navigation was only 5 minutes. The resected tumor was 1.5 1.5 1.2 cm and weighed 2.1 g. The tumor was round with a thin capsule. Microscopically,
Fig 2. Representative views of video-assisted thoracoscopy are shown. A, No tumorous lesion was found by simple thoracoscopic examination. Radioactivity per 1 second is indicated on referenced areas, showing approximately 2fold activity at point where ectopic parathyroid adenoma was located. B, Intraoperative thoracoscopic view of ectopic parathyroid gland (arrow) located underneath mediastinal pleura. the tumor was composed of chief cells with round nuclei and clear cytoplasm without cell atypia and was diagnosed as an ectopic hyperplastic parathyroid gland. On the 14th day, the patient went without event back to her local hospital to continue hemodialysis, supplemented with alfacalcidol (2 µg) and calcium lactate (6 g). The serum levels of parathyroid hormone and calcium were decreased to 41 pg/mL and 6.2 mg/dL, respectively, on the 7th day. No symptoms suggesting hypoparathyroidism or hyperparathyroidism have been found up to this time.
DISCUSSION Ectopic parathyroid swelling with hyperparathyroidism is often found, as in our case, in patients with chronic renal failure, known as compromised hosts. Thus, to apply minimally invasive video-assisted thoracoscopic surgery (VATS)1,2 in these cases is considered reasonable and suitable. As Prinz et al1 stated, the location of the lesion should be evaluat-
Onoda et al 19
Surgery Volume 132, Number 1 ed precisely before the operation. However, lesions are often hidden beneath the pleura or located between the mediastinal structures. Moreover, a fine sense of touch is not available in VATS, so sometimes it is difficult to find the small lesions located beyond the mediastinal pleura, especially in cases with a deformed thorax, such as ours. We have already applied VATS in 4 cases of ectopic mediastinal parathyroid gland, and in those, it took 30 to 60 minutes to identify the lesion intraoperatively even if the location had been precisely identified preoperatively in relation to the other normal visible structures. To overcome this difficulty, shorten the operation time, and reduce the stress to the surgeon, we combined the RI-navigation method with VATS to identify underlying small lesions. Preoperative RI detection and intraoperative navigation with 99mTc MIBI is a very elegant tool for pointing out the responsive lesion in the parathyroid operation, and the reliability of the method has already been reported.3,4 The mean emitted radioactivity of the parathyroid adenoma in the neck was reported to be 32% higher than that of the background neck emission.3 In our case, we observed radioactivity at the point of the hyperplastic gland that was more than double that of the background neck emission. As shown in Fig 1, B, the background radioactive emission in the mediastinum was similar to that in the neck. High background radioactivity is unavoidable in the neck, even when a probe with very strict directional resolution is used, because of 99mTc-MIBI accumulation in the thyroid gland. However, we were able to flame off the background radioactivity of the heart in VATS by directing the probe so as not to point at the heart while it was surveying.
Clear 99mTc-MIBI accumulation in the lesion and clear thoracic space without adhesion was necessary for this technique to be applied. The indications for the use of this technique might be limited because of the cost, risk of radiation exposure, and necessity for intimate cooperation between the surgeon, radiologist, and respective staffs of the dialysis room and operation room. Furthermore, most lesions can be identified precisely only from the video view. However, by using the navigation technique to identify the ectopic parathyroid hidden beneath the pleura, we could minimize not only the time, but also the unnecessary wound in the mediastinum. Moreover, the stress imposed on the surgeon by searching for the lesion and confirming its complete removal is far lower when this technique is used. This RI-navigated VATS is likely to be one of the most reliable and safe methods for removing ectopic parathyroid in the mediastinum. We believe that this technique will contribute to better prognoses for patients with hyperparathyroidism by reducing the operative complications and expanding the surgical indications. REFERENCES 1. Prinz RA, Lonchyna V, Carnaille B, Wurtz A, Proye C. Thoracoscopic excision of enlarged mediastinal parathyroid glands. Surgery 1994;116:999-1005. 2. Ishikawa T, Nishimura S, Michigami S, Nishiguchi Y, Yoshikawa K, Nagayama M, et al. Thoracoscopic excision of mediastinal parathyroid tumor. Final program and abstracts. SAGES 1997;74. 3. Norman J, Chheda H. Minimally invasive parathyroidectomy facilitated by intraoperative nuclear mapping. Surgery 1997;122:998-1004. 4. Norman J, Denham D. Minimally invasive radioguided parathyroidectomy in the reoperative neck. Surgery 1998;124:1088-93.