Video-Assisted Thoracoscopic Surgery Is a Safe and Feasible Technique for Mediastinal Parathyroid Lesions

Abstract

Introduction:

Hyperfunctional ectopic parathyroid glands in the mediastinum pose a challenge to diagnosis and require optimal surgical management. Video-assisted thoracoscopic surgery (VATS) has emerged as a promising minimally invasive approach, offering potential benefits in terms of both patient comfort and oncological principles. This study aimed to evaluate the effectiveness and safety of VATS for the treatment of hyperfunctional ectopic parathyroid glands in the mediastinum.

Methods:

Among the 538 patients with mediastinal tumors who underwent thoracoscopic surgery at Istanbul University (2008–2021), 11 exhibited hyperfunctional ectopic parathyroid glands. The localization of the glands was performed using various diagnostic techniques, including neck ultrasound, sestamibi scan, CT (computerized tomography), and SPECT (Single-photon emission computed tomography). VATS (Video-assisted thoracoscopic surgery) was used to remove ectopic parathyroid glands in all 11 patients, with no need for conversion to open surgery.

Results:

The pathological results showed that VATS successfully removed the ectopic glands in all 11 patients. Serum parathyroid hormone (PTH) levels were monitored intraoperatively, and frozen sections were used to confirm the presence of parathyroid adenomas in all cases. Postoperative analysis showed that PTH levels dropped by at least 50% within 10–15 minutes after adenoma removal.

Conclusion:

VATS is a safe and effective method for the treatment of hyperfunctional ectopic parathyroid glands in the mediastinum with a low risk of complications.

Introduction

The superior parathyroid glands originate from the fourth pharyngeal pouch, whereas the inferior parathyroid glands originate from the third pharyngeal pouch. Unlike their superior counterparts, the inferior parathyroid glands must traverse a greater distance to reach the classic cervical anatomical position.¹ Consequently, ectopic inferior parathyroid glands are frequently found within or around the thymus, given their shared origin from the third pharyngeal pouch.²

Understanding the concept of primary and secondary hyperparathyroidism is essential for the surgical intervention precision. Primary hyperparathyroidism predominantly stems from a solitary parathyroid adenoma, accounting for approximately 85% of all cases. Conversely, secondary hyperparathyroidism often manifests as hyperplasia rather than adenoma, affecting multiple mediastinal parathyroid glands.^3–4 This distinction underscores the importance of discerning the histopathological aspects preceding surgical interventions.⁵

Ectopic parathyroid glands can complicate hyperparathyroidism management, necessitating surgical intervention in approximately 15% of cases.² While most ectopic glands in the superior mediastinum can be accessed through a cervical incision, a small subset (1%–3%) may require thoracic surgical procedures.⁶ The precise localization of hyperfunctional mediastinal parathyroid is paramount in such cases.

Hyperfunctional parathyroid glands can manifest anywhere within the mediastinum, with common sites. including the thymus, periaortic region, and the peritracheal area.⁷ Preoperative localization techniques, such as neck ultrasound, sestamibi scans, and computed tomography, are essential for surgical planning, optimizing the choice of approach and minimizing invasiveness.⁶

The importance of evaluating cervical parathyroid gland status cannot be overstated, particularly in patients with prior surgeries.³ The classic approach advocates neck exploration before mediastinal exploration, unless specific indications dictate otherwise.⁸

Advancements in localization techniques have revolutionized the surgical strategies for hyperfunctional mediastinal parathyroids.⁹ Minimally invasive approaches, such as partial sternotomy and video-assisted thoracoscopic surgery (VATS), are increasingly preferred, offering reduced complications compared with traditional median sternotomy.¹⁰

Intraoperative parathyroid hormone (PTH) monitoring and frozen section analysis serve as valuable adjuncts, facilitating real-time decision-making and confirmation of parathyroid adenomas. These methodologies contribute to the precision and efficacy of surgical intervention in patients with hyperparathyroidism.^11,12

Patients and Methods

Eleven of 538 patients with mediastinal tumors underwent thoracoscopic surgery between January 2008 and December 2021 at Istanbul University, Istanbul Medical Faculty Department of Thoracic Surgery. Eleven patients diagnosed with mediastinal parathyroid tumors were included in this study, and patient data were analyzed retrospectively.

We examined the clinical presentation, symptoms, preoperative radiologic findings, preoperative scintigraphy results, preoperative and postoperative serum calcium levels, serum phosphorus levels, serum PTH levels, postoperative early and late complications, chest tube drainage, length of hospital stay, and pathological examination findings.

All patients were observed by a multidisciplinary team of endocrinologists, endocrine surgeons, radiologists, and thoracic surgeons who were experienced on mediastinal surgery.

Surgical Technique

The operations were performed under general anesthesia using a double-lumen endotracheal tube. Carbon dioxide insufflation was not used perioperatively. A three-port VATS approach was used for tumors located in the anterior and superior mediastinum, with two 10-mm ports and a 5-mm port. Skin incisions were made in the second intercostal space along the anterior axillary line, fifth intercostal space along the middle axillary line, and fifth intercostal space along the submammary area. The portal approach is utilized for tumors localized in the posterior mediastinum. Approaching the posterior mediastinal lesions via biportal VATS while the patient was positioned in the lateral decubitus position, the first skin incision was made in the fourth intercostal space used as the utility port, and the second one was made in the seventh intercostal space along the midaxillary line. We used a fleet silicone drain via a 5-mm port. The drain was generally removed 24–48 hours after the surgery. All patients had adjusted serum calcium and PTH levels measured in the evening and the following morning.

Results

There were 7 women and 4 men. Age ranged from 16 to 72 years, with a median age of 42. There were no significant age differences between the sexes (P = 0.276). The patients underwent mediastinal parathyroid tumor resection via VATS, and their characteristics are summarized in Table 1. The patients presented with the following symptoms before surgery: weakness in 3, bone pain in 4, muscle cramps in 2, and night sweats in 2. Preoperative clinical examination was performed by the primary surgeon after a diagnosis of hyperparathyroidism. Routine preoperative biochemical evaluation was performed on each patient, and significant results are described in Table 1. Preoperative ^99mTc-MIBI scintigraphy was performed in 9 patients, which diagnosed 6 patients correctly. PET/BT was performed in 2 patients. The tumor was located in the superior mediastinum in 2 patients, anterior mediastinum in 7 patients, and posterior mediastinum in 2 patients. Nine patients underwent triportal surgery, and 2 of them had biportal surgery. There were no significant operative durations between port count selection and localization for tumor placement. The median hospital stay was not related to port selection and mediastinal tumor localization. Postoperatively, the only countable early complication was hypocalcemia in 3 patients who were treated with parenteral calcium administration. The median chest tube duration was 2 days (1–4 days), and no excessive drainage was observed on follow-up days. The median length of stay was 2.64 days (1–14 days). No readmissions occurred within 30 days. Table 2 shows postoperative detailed results alongside patient characteristics.

Table 1.

Patient Demographics and Preoperative Characteristics

Clinical data	Case1	Case2	Case3	Case4	Case5	Case6	Case7	Case8	Case9	Case10	Case11
Age (years)	42	16	40	72	65	17	38	62	55	64	42
Gender	Female	Male	Female	Male	Female	Male	Female	Female	Male	Female	Female
Symptom	Bone pain	Muscle cramps	Bone pain	Muscle cramps	Bone pain, weakness	Weakness	Weakness	Negative	Weakness	None	Bone pain
Tumor location in mediastinum	Posterior	Superior, anterior	Anterior	Superior	Anterior	Anterior	Anterior	Anterior	Posterior	Superior	Anterior
Tumor size (cm)	2	1.3	0.8	1	1.6	0.6	1.2	1.8	4.2	2.3	0.8
^99m Tc-MIBI scintigraphy	Positive	Positive	Positive	Negative	Positive	Negative	Positive	Negative	Positive	NA	NA
Serum calcium level (mg/dL)	12.0	12.5	10.75	11.2	11.6	10.9	10.7	11.8	12	10.2	10.5
Serum-corrected calcium level	12.5	12.3	10.8	11.4	11.4	10.7	10.6	11.8	11.9	10.2	10.3
Albumin	3.97	4.8	4.32	4.2	4.69	4.71	4.5	4.4	4.7	4.47	4.7
Serum phosphorus level (mg/dL)	2.2	3.1	2.01	1.8	2.6	3.6	2.1	3.3	2	2.8	2.2
Serum intact-PTH level (pg/dL)	162	110	113	104	569	86	58	122	542	43	100

Table 2.

Postoperative Findings and Pathological Results

Intra- and postoperative findings	Case1	Case2	Case3	Case4	Case5	Case6	Case7	Case8	Case9	Case10	Case11
Operation	2-port	3-port	3-port	3-port	3-port	3-port	3-port	3-port	2-port	3-port	3-port
Postoperative serum calcium level (mg/dL)	7.3	10.9	9.1	9.51	8.5	9.1	9.6	9.8	9.8	8.6	9.1
Corrected calcium level	7.7	10.7	9.3	9.8	8.3	8.9	9.6	9.9	9.6	8.6	8.9
Postoperative phosphorus level (mg/dL)	6.1	2.17	4	3.02	2.1	5.1	2.4	3.8	2.6	3.3	2.7
Postoperative serum intact-PTH level (pg/dL)	7	4.1	23.5	1.86	122.9	23.2	12.1	78	68.6	12	29.1
Intraoperative complication	—	—	—	—	—	—	—	—	—	—	—
Duration of chest tube drainage (day)	1	2	3	3	7	2	2	4	1	2	2
Postoperative complication	—	—	—	—	Hypocalcemia	Hypocalcemia		—	—	—	Hypocalcemia, pneumonia
Length of hospital stay (day)	1	2	3	3	8	2	2	4	2	2	14
Pathological examination findings	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid adenoma	Parathyroid carcinoma	Parathyroid adenoma

The AAES’s (American Association of Endocrine Surgeons) guidelines for definitive management of primary hyperparathyroidism recommend a successful cure as a reduction in the PTH level by at least 50% within 10–15 minutes after the removal of the adenoma, which should be sustained on the first postoperative day.¹³ Compatible with the guidelines, all patients had a biochemical cure. The preoperative median PTH and serum Ca levels were 110 pg/dL (43–569 pg/dL) and 11.286 mg/dL (10.2–12.5 mg/dL), respectively. The postoperative median PTH and serum Ca levels were 23.2 pg/dL (1,9–122.9) and 9.21 mg/dL (7.3–10.9 mg/dL). Pathological examination findings indicated parathyroid adenomas in 10 patients and parathyroid carcinomas in 1 patient. The median tumor size was 13 mm (0.6 cm–4.2 cm).

The most frequent complication was transient hypocalcemia in 3 patients and pneumonia in 1 patient.

Discussion

Accurate preoperative localization is essential for successful surgical excision of an ectopic mediastinal parathyroid adenoma. Many patients with ectopic mediastinal parathyroid disease are diagnosed only after undergoing bilateral neck exploration, which does not cure the condition. Therefore, precise preoperative localization is key to ensuring successful outcomes.⁴

In cases of persistent primary hyperparathyroidism (PHPT), specialized imaging studies can be performed to locate the target lesion for surgical resection. These lesions can be small and difficult to distinguish from the surrounding tissues. As a result, they may need to be removed along with the surrounding tissue, such as the thymus in the case of intrathymic parathyroid adenomas, or with minimal surrounding tissue, as in the case of aortopulmonary parathyroid adenomas. The weight of the operative specimens can provide insight into the extent of tissue removal required to successfully remove an adenoma.

Parathyroid adenoma localization can be determined using 99mTc-MIBI scintigraphy and PET/CT.¹⁰

In this study, 99mTc-MIBI scintigraphy was conducted in 9 patients, correctly diagnosing 6 of them. The remaining 2 patients underwent PET/CT for further evaluation.

Ectopic mediastinal parathyroid tumors are commonly found in the thymus, with an incidence ranging from 67% to 80%.^13,14 In our study, 7 patients had tumors located in the thymus.

Since 2008, we have performed parathyroid adenoma surgery via VATS. We prefer a three-port approach for lesions located in the anterior and superior mediastinum, and a two-port approach for lesions located in the posterior mediastinum. When using a three-port approach, we used a semilateral decubitus position, whereas for a two-port approach, we preferred a lateral decubitus position.

In our study, the median chest tube duration and length of hospital stay were comparable with those reported in the literature. However, one patient had a longer hospital stay (14 days) due to postoperative hypocalcemia.

In our study, we successfully performed VATS in all cases without the need to resort to open surgery. We attribute this to our extensive experience with VATS thymectomy and a thorough preoperative examination of patients.

In the treatment of parathyroid adenomas, it is important to exercise caution during surgery to prevent postoperative metastasis and recurrence, which can occur if the tumor capsule is damaged during surgery.¹⁵ Rattner et al. emphasized the need for extreme care to prevent such complications.¹⁵ In addition, Akerström et al. emphasized that in addition to exercising caution during the procedure, surgeons should not divide the parathyroid gland in the surgical field.¹⁶ In our study, all 5 patients underwent complete thymectomy without intraoperatively grasping the tumor or the surrounding area, thereby preventing damage to the tumor capsule. We believe that this approach helped prevent postoperative recurrence of hyperparathyroidism.

Conclusions

VATS excision is a safe method for the treatment of parathyroid adenomas when accurate localization is performed.

Data Access Statement

The data used in this study are available upon request from the corresponding author, subject to any necessary permissions or approvals. All results related to the data already shared in the tables with the main content. Due to confidentiality agreements, certain restrictions may apply to accessing the data. Requests for access to the data should be directed to Arda SARIGÜL at sarigul.arda.md@gmail.com

Ethical Compliance

All procedures performed in studies involving human participants were in accordance with the ethical standards of Istanbul University Istanbul School of Medicine Ethics Committee (2023/704) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the Ethics Committee of Istanbul University Istanbul School of Medicine.

Footnotes

Author Contributions

S.D. and A.S. contributed to the design and implementation of the research. A.S. and E.E. contributed to the analysis of the results and to the writing of the article. B.Ö., A.D., M.K., and S.A.T. conceived the original and supervised the project.

Disclosure Statement

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding Statement

This study was not supported by any funding.

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