https://orcid.org/0009-0004-0912-615X
Abstract
Mediastinal ectopic parathyroid adenomas are an uncommon cause of primary hyperparathyroidism and a frequent source of failed cervical exploration. We report three patients with deeply located mediastinal adenomas treated using minimally invasive thoracoscopic approaches—two robot-assisted (RATS) and one video-assisted (VATS). Preoperative localization was achieved with SPECT/CT and, when required, 18F-fluorocholine PET/CT, enabling accurate identification of lesions in para-aortic and aortopulmonary regions. Complete excision was confirmed in all cases by intraoperative parathyroid hormone monitoring according to the Miami criterion. One patient developed a minor pneumothorax; no major complications occurred. All patients achieved a durable biochemical cure. These cases highlight the role of multimodal imaging and demonstrate that minimally invasive thoracoscopic surgery represents a safe and effective treatment option for complex mediastinal ectopic parathyroid adenomas, with the choice of surgical approach tailored to lesion characteristics and surgical expertise.
Introduction
Primary hyperparathyroidism (PHPT) is among the most frequent endocrine disorders and is usually caused by a solitary cervical adenoma [1]. Ectopic parathyroid glands occur in 1%–2% of cases and may give rise to persistent or recurrent hyperparathyroidism when missed at neck exploration [2]. Deeply situated mediastinal adenomas remain particularly challenging because of their variable embryologic descent and close relationship to critical intrathoracic structures.
Accurate preoperative localization is essential to avoid failed operations. Although 99mTc-sestamibi SPECT/CT remains the standard functional imaging modality, its sensitivity declines for small or deeply positioned lesions [3]. In such circumstances, 18F-fluorocholine PET/CT provides superior contrast and anatomical definition, often revealing lesions undetected by conventional imaging [4, 5].
Historically, deep mediastinal ectopic adenomas required sternotomy or thoracotomy, leading to substantial postoperative morbidity. Minimally invasive thoracoscopic approaches have since supplanted open surgery. Both video-assisted thoracoscopic surgery (VATS) and robot-assisted thoracoscopic surgery (RATS) are established minimally invasive techniques that provide effective access to deeply located mediastinal lesions [6]. Here, we report three consecutive patients with mediastinal ectopic parathyroid adenomas managed successfully by RATS or VATS, emphasizing imaging-guided planning, operative technique, and outcomes.
Case series
Three patients with PHPT due to mediastinal ectopic parathyroid adenomas were treated using minimally invasive thoracoscopic approaches.
A 55-year-old woman was referred for asymptomatic hyperparathyroidism (PTH 140 pg/mL, calcium 11.4 mg/dL). Cervical ultrasonography was non-localizing. 99mTc-sestamibi SPECT/CT demonstrated a 16 × 6 mm hypermetabolic focus in the left anterior mediastinum, adjacent to the great vessels. Given the deep location, a transcervical approach was considered unsafe, and a robot-assisted thoracoscopic resection was performed. The adenoma, located between the ascending aorta and pulmonary artery beneath the left phrenic nerve, was excised en bloc. Intraoperative PTH decreased from 330 pg/mL to 59 pg/mL (>80% reduction), confirming a biochemical cure according to the Miami criterion [7]. Histopathological examination revealed a parathyroid adenoma. The postoperative course was complicated by a small pneumothorax requiring short-term drainage. The patient remains asymptomatic and normocalcemic at the 3-year follow-up.
A 77-year-old woman presented with fatigue and hypercalcemia (calcium 10.9 mg/dL, PTH 183 pg/mL). Ultrasonography was inconclusive, while SPECT/CT showed uptake in the aortopulmonary window. This finding was further confirmed by 18F-fluorocholine PET/CT. Following a multidisciplinary evaluation, a left-sided robot-assisted thoracoscopic approach was selected. The adenoma, embedded within pericardial fat, was completely excised (Video 1). Intraoperative PTH levels decreased from 298 pg/mL to 89 pg/mL (>70% reduction) within 15 minutes. Histopathological examination revealed a parathyroid adenoma. The postoperative course was uneventful, and the patient was discharged on postoperative Day 3. She remains normocalcemic with complete symptom resolution at 1-month follow-up.
A 62-year-old man with long-standing hyperparathyroidism (PTH 365 pg/mL, calcium 13 mg/dL) was found to have a retrosternal mediastinal lesion above the aortic arch on SPECT/CT (Figs 1 and 2). Additional mediastinal and abdominal lymphadenopathy was identified on 18F-FDG PET/CT, performed for differential diagnostic purposes. A video-assisted thoracoscopic approach was undertaken using a three-port technique combined with a muscle-sparing minithoracotomy to allow both adenoma resection and lymph node sampling. The ectopic gland and enlarged nodes were excised without complications. Intraoperative PTH decreased by more than 60%, confirming a cure. Histopathological examination revealed a parathyroid adenoma and reactive lymphoid hyperplasia. The postoperative course was uneventful, and the patient remains biochemically cured under hematologic follow-up.
Preoperative contrast-enhanced CT scan (axial view) demonstrating the retrosternal mediastinal ectopic parathyroid adenoma in Case 3. The lesion is located posterior to the sternal manubrium and superior to the aortic arch, deep within the anterior mediastinum, making a transcervical approach unsafe.
Preoperative 18F-fluorocholine PET/CT of Case 3. (A) Sagittal fused PET/CT image showing intense focal uptake at the retrosternal level, confirming the presence and depth of the ectopic parathyroid adenoma. (B) Axial fused PET/CT image illustrating the lesion’s mediastinal position relative to the great vessels and sternum, providing essential guidance for thoracoscopic planning.
Discussion
Ectopic mediastinal parathyroid adenomas represent a small proportion of PHPT but are a frequent cause of failed cervical exploration. Their embryologic origin from the third and fourth branchial pouches explains their variable intrathoracic distribution—most commonly within thymic or para-aortic fat or in the aortopulmonary (AP) window—often in close proximity to major vascular structures. This anatomical complexity makes both diagnosis and surgical management particularly challenging.
Accurate preoperative localization is essential for selecting the optimal surgical approach. Although 99mTc-sestamibi SPECT/CT remains the standard imaging modality, its sensitivity decreases for small or deeply located mediastinal lesions. In such cases, 18F-fluorocholine PET/CT provides superior spatial resolution and contrast, improving lesion detection when conventional imaging is inconclusive [3]. This advantage was evident in our series, where fluorocholine PET/CT enabled clear identification of an AP-window adenoma that was only faintly visualized on sestamibi imaging.
Historically, deeply located mediastinal adenomas required sternotomy or thoracotomy, procedures associated with significant morbidity [8]. Minimally invasive thoracoscopic techniques have largely replaced open surgery. Both VATS and RATS are established minimally invasive approaches that allow safe and effective resection of mediastinal ectopic parathyroid adenomas. The choice of surgical technique should be individualized according to lesion location, surgeon experience, and institutional expertise [9, 10]. Given the limited number of patients in our series and the predominance of robotic procedures, no comparison between the two approaches can be drawn.
In all patients, intraoperative parathyroid hormone monitoring confirmed complete excision according to the Miami criterion, and a durable biochemical cure was achieved. Only one minor postoperative pneumothorax occurred, supporting the safety and reproducibility of these minimally invasive approaches.
Rather than supporting one minimally invasive approach over the other, our findings underline the feasibility of thoracoscopic management when combined with appropriate preoperative localization and intraoperative PTH monitoring. Larger comparative studies are warranted to determine whether one minimally invasive approach offers clinically relevant advantages over the other in terms of operative outcomes, complications, and cost-effectiveness.
In summary, minimally invasive thoracoscopic approaches provide a safe and effective treatment for mediastinal ectopic parathyroid adenomas. Our experience highlights the importance of accurate preoperative localization, appropriate patient selection, and intraoperative parathyroid hormone monitoring in achieving successful surgical outcomes, regardless of the minimally invasive thoracoscopic technique adopted.
Conclusion
Minimally invasive thoracoscopic surgery provides a safe and effective option for the management of deeply located mediastinal ectopic parathyroid adenomas that are inaccessible through a cervical approach. Both robot-assisted and video-assisted thoracoscopic approaches can be successfully employed in appropriately selected patients, with the choice of technique tailored to lesion characteristics and surgical expertise. When combined with advanced imaging and intraoperative parathyroid hormone monitoring, these approaches enable accurate localization, complete excision, and durable biochemical cure in anatomically complex cases.
Author contributions
All authors contributed to data collection, surgery, writing, and approval.
Supplementary material
Supplementary material is available at Journal of Surgical Case Reports online.
Conflicts of interest
No conflicts of interest declared.
Funding
No funding received.
Data availability
Data available upon request.
Ethics statement
Written informed consent was obtained from all patients.
Patient perspective
All patients expressed satisfaction with the minimally invasive thoracoscopic approach, highlighting rapid recovery, minimal discomfort, and prompt normalization of calcium levels. They reported confidence in the preoperative counseling and surgical process and appreciated the multidisciplinary management. None experienced postoperative hypocalcemic symptoms, and all resumed daily activities quickly, reinforcing the perceived value of a tailored, minimally invasive strategy.
