Robotic-Assisted Resection of Middle Mediastinal Ectopic Parathyroid Adenoma

A sixty-one-year-old woman presented with a history of incidentally noted hypercalcemia and worsening bone pain over the preceding weeks. Her past medical history included gastroesophageal reflux and previous smoking history with no prior thoracic surgeries. Labs demonstrated a calcium level of 11.4 mg/dL with an elevated parathyroid hormone (PTH) of 130 pg/mL. Parathyroid hormone related peptide was negative.

A Sestamibi scan noted increased radionucleotide uptake in the middle mediastinum, and CT scan confirmed a 1.7 cm nodule in the aortopulmonary window. Because of the lesion’s anterior position relative to the trachea, it was best accessed from the right chest. The potential risk of left recurrent laryngeal nerve injury was also decreased with a right-sided approach.

The surgery began with the patient in the left lateral decubitus position with a double lumen endotracheal tube. Four Thoracoport incisions were made, three in the eighth intercostal space and one in the anterior sixth space. A thirty-degree camera was placed in the eighth space midaxillary line port.

Next, the lung was reflected anteriorly, and the surgery proceeded with subcarinal dissection. The esophagus was then mobilized from the left tracheobronchial angle. The left mainstem bronchus was then mobilized, and the carina was freed, as well as the inferior trachea and bilateral mainstem bronchi. The team then turned their attention to the pleura along the superior vena cava (SVC), incising it and removing level four nodes to facilitate further exposure. The azygous vein was then divided, and an assistant port was added in the anterior fourth intercostal space to facilitate further dissection along the anterior trachea. At this point, an additional instrument port was placed posteriorly in the seventh intercostal space to allow for a more direct view of the mediastinum. The camera was moved one space posterior, and the dissection was continued.

Next, the team dissected further medially, between the trachea and SVC, visualizing the right main pulmonary artery along the inferior aspect of the dissection. The pericardium was entered with release of significant fluid, with further dissection demonstrating the ascending aorta. Additional dissection mobilized the middle mediastinal tissue from the surrounding airway and vascular structures. Indocyanine green was administered, allowing for confirmation of the nodule in its expected anatomic location. Using a no-touch technique, this was carefully resected. The left recurrent laryngeal nerve along the left anterior lateral aspect of the trachea was visualized and avoided. Ten minutes following resection, PTH level was measured, showing a decrease from 130 to 40 pg/mL. The patient's postoperative course was uncomplicated, and her calcium levels have since normalized.

For any parathyroid surgery, a PTH level should be taken both preoperatively as well as at five to ten minute intervals following removal of the adenoma. Because of its short half-life, the PTH should drop by at least 50 percent within ten minutes of resection. It is essential to avoid rupturing the adenoma capsule, as tissue deposits can lead to parathyromatosis, implants of functional tissue resulting in persistent hyperparathyroidism.

References

1. LoCicero Ja, LoCicero JIIIa, Shields TW. Shield's General thoracic surgery. Eighth edition / Joseph LoCicero. ed.
2. Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice. 20th ed: Elsevier; 2016.

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