Mediastinal Parathyroid Adenoma Resection Through Robotic Video-Assisted Thoracoscopy Utilizing Firefly Fluorescence

Introduction:

Parathyroid adenomas are ectopic in up to 20% of patients with 1%–2% located in the mediastinum and inaccessible through cervical incisions. ¹ Primary hyperparathyroidism (PHP) from such adenomas presents unique diagnostic and surgical challenges. In addition to the routine comprehensive biochemical evaluation to confirm PHP, preoperative imaging is key. Mediastinal parathyroid adenomas (MPAs) have most effectively been identified by Sestamibi-Tc99m scan and computed tomography of the chest, including recent advances using 4DCT protocols.^2–4 Despite improved preoperative localization, intraoperative observation of a small parathyroid in the mass of mediastinal thymic tissue is exceptionally difficult. Indocyanine green (ICG) fluorescence has been used with diverse surgical applications to illuminate tissues of interest, including parathyroids. ⁵ The da Vinci Si surgical robots (Intuitive Surgical, Sunnyvale, CA) have built-in Firefly™ technology (Novadaq Technologies, Mississauga, Canada) that detects ICG fluorescence in real time. This video illustrates an innovative strategy for removal of MPAs by using robotic video-assisted thoracoscopy (VATS) with Firefly.

Case:

A 66-year-old woman with incidental hypercalcemia was found to have PHP based on elevated serum calcium 10.8 mg/dL (nl 8.6–10.6) and ionized calcium 5.7 mg/dL (nl 4.5–5.3), elevated parathyroid hormone 89 pg/mL (PTH, nl 15–65), and normal levels of vitamin D25, albumin, creatinine, and 24-hour urine calcium. She had fatigue, memory changes, arthralgias, and osteoporosis. Sestamibi-Tc99m imaging localized a parathyroid adenoma to the mid-anterior mediastinum. A subsequent neck ultrasonography showed a normal thyroid gland without identifying parathyroid disease. 4DCT was thus used to delineate the precise anatomic relationship between mediastinal structures and guide operative planning. Because the adenoma was inferior to the innominate vein, we elected a surgical approach through the left thoracic cavity. The patient received Sestamibi-Tc99m injection 1 hour before surgery to allow ex vivo radiotracer detection in the excised specimen. Patient positioning was typical for VATS (supine, three ports in lateral left chest). The video illustrates optimal timing of ICG injection and technical steps to expose anterior mediastinal anatomy and perform the thymectomy. ICG uptake into the MPA was best seen only after skeletonizing the innominate vein as the adenoma was located deeper and more medial than expected. The thymectomy specimen was externalized and then examined to confirm that the MPA was resected in its entirety: the gamma probe detected greatest radioactivity within a grossly intact 10 × 9 × 7 mm nodule, which was hypercellular parathyroid tissue by histology. Intraoperative PTH decreased appropriately from 198 to 19 pg/mL after MPA removal. The patient had an uncomplicated postoperative course and was discharged home 2 days later. Six-month follow-up revealed calcium 9.6 mg/dL, PTH 45 pg/mL, mid-normal range vitamin D 25 (41 ng/mL), and symptom resolution.

Conclusion:

To our knowledge, this is the first reported case of robotic VATS, facilitated by Firefly, for removal of a mediastinal ectopic parathyroid adenoma. We highlight key steps in the management of MPAs: the need for precise preoperative localization with dual imaging, benefits of novel minimally invasive robotic surgery, and innovative use of fluorescence for in vivo visualization, radiotracer for ex vivo detection, and intraoperative PTH for biochemical confirmation of cure.

No competing financial interests exist.

Runtime of video: 6 mins 55 secs