Gen Thorac Cardiovasc Surg DOI 10.1007/s11748-015-0587-y
Robotic resection of a mediastinal parathyroid cyst Pauline Go1 • Jenna Watson1 • Zhichun Lu2 • Arthur Carlin1 • Zane Hammoud3
Received: 3 August 2015 / Accepted: 1 September 2015 Ó The Japanese Association for Thoracic Surgery 2015
Abstract Mediastinal parathyroid cysts (PC) are rare, benign lesions, reported in fewer than 150 cases worldwide. Although most are asymptomatic and discovered incidentally on imaging, symptoms of dyspnea, dysphagia, hoarseness, palpitations, hypercalcemia, and innominate or jugular venous thrombosis have been reported. Sternotomy or thoracotomy has traditionally been the approach used to resect mediastinal PCs. We describe the first reported case of a robot-assisted resection of a mediastinal PC. Keywords Robotic Mediastinum Thoracoscopy VATS Parathyroid
Introduction Mediastinal parathyroid cysts (PC) are rare, benign lesions, first described in 1925 by de Quervain . Fewer than 150 cases have been reported worldwide . PC are reported to cause dyspnea, dysphagia, hypercalcemia and thrombosis [3–5]. In most cases, PC are asymptomatic and discovered incidentally on radiographic imaging [2, 6]. Differential diagnosis includes bronchogenic cyst, duplication cyst, & Zane Hammoud [email protected] Pauline Go [email protected] 1
Department of Surgery, Henry Ford Hospital, Detroit, MI, USA
Department of Pathology and Laboratory Medicine, Henry Ford Hospital, Detroit, MI, USA
Division of Thoracic Surgery, Henry Ford Hospital, 2799 W. Grand Blvd, K-14, Detroit, MI 48202, USA
thymic cyst, and esophageal or pleuropericardial cysts . Resection has traditionally been accomplished by sternotomy or thoracotomy. However, thoracoscopic resection has been reported [2, 4, 8]. We describe a case of robotassisted resection of a mediastinal PC.
Case report A 61-year-old male with history of hypertension, chronic renal insufficiency (CRI) and chronic obstructive pulmonary disease (COPD) presented with exertional dyspnea and fatigue over 2–3 years. Physical examination was unremarkable. Computed tomography (CT) revealed a well-demarcated, homogenous right paratracheal cystic mass measuring 8.5 9 8.4 cm, extending to the thoracic inlet, causing significant tracheal and esophageal deviation and innominate vein compression. Magnetic resonance imaging (MRI) demonstrated a cystic mass with mild hyperintensity on T1 and hyperintensity on T2 weighting (Fig. 1). Endobronchial ultrasound (EBUS) revealed a well-demarcated cyst causing 70 % tracheal narrowing. Transbronchial needle aspiration (TBNA) removed 250 mL of dark brown fluid, with substantial improvement in tracheal patency and symptoms. Fluid analysis was positive for hemosiderin and cytology was negative for malignancy. A presumptive diagnosis of bronchogenic cyst was made and resection planned. Prior to surgery, the patient underwent repeat EBUSTBNA with aspiration of 270 mL of fluid to facilitate operative manipulation of the cyst. At surgery, he was intubated using a fiberoptic bronchoscope and single lung ventilation was utilized. Diagnostic thoracoscopy was performed verifying no pleural disease. Carbon dioxide was insufflated to a pressure of 8 mmHg. Five ports were
Gen Thorac Cardiovasc Surg Fig. 1 a MRI demonstrating 8.5 9 8.4 cm homogenous, cystic lesion with b compression and anterior displacement of the right innominate vein, c significant tracheal compression and deviation and d extension to the thoracic inlet
Fig. 2 Port placement schematic (5th port not shown)
used (Fig. 2) and the da Vinci Si surgical system (Intuitive Inc., Sunnyvale, CA, USA) docked. The cyst was located above the azygous vein, on the main trachea. The vagus
nerve and azygous vein were draped over the cyst and were successfully dissected and preserved. The cyst wall was thick and did not have the typical thin-walled appearance of a bronchogenic cyst. Given this appearance, a piece of cyst wall was sent for frozen analysis and confirmed to be benign. Further dissection proximally revealed the cyst to be densely adherent to the subclavian vein and innominatecaval junction, extending to the base of the neck. Therefore, the cyst was transected, leaving a small portion attached to the vessels. Operative blood loss was negligible. Total operative time was 4.5 h, with under 4 h spent at the console. The patient was extubated in the operating room and his postoperative course was unremarkable. Final pathology revealed a cystic parathyroid gland with intracystic hemorrhage. Microscopically, the cyst wall had focal flattened epithelial lining and contained islets of normal parathyroid cells, which stained positive for parathyroid hormone (PTH). Review of preoperative records from the patient’s primary care physician (PCP) revealed elevated serum calcium of 11.9 mg/dL (range 8.6–10.3 mg/dL) and PTH of 232 pg/mL (range 15–65 pg/ mL). On postoperative follow-up, his dyspnea and fatigue had completely resolved. Given a history of CRI and persistent elevation in PTH with non-suppressed calcium, technetium sestamibi scan with neck dissection and completion parathyroidectomy was offered. However, since he was
Gen Thorac Cardiovasc Surg
asymptomatic, he elected to undergo surveillance with his PCP. One month postoperatively his calcium and PTH had decreased to 10 mg/dL and 89 pg/mL, respectively.
Comment First described in 1880 by the Swedish anatomist Sandstro¨m, PC are rare, non-neoplastic lesions, usually found in the neck . In 1925, Swiss surgeon de Quervain reported the first removal of a mediastinal PC . Since then, fewer than 150 cases have been reported worldwide . It has been postulated that the atypical location of PC results from descent or enlargement of cervical parathyroid tissue into the mediastinum due to their weight and intrathoracic negative pressure or formation from heterotopic mediastinal parathyroid glands . Dyspnea resulting from tracheal deviation or narrowing, dysphagia from esophageal compression, and hoarseness from impingement upon the recurrent laryngeal nerve are the most commonly reported symptoms arising from large mediastinal PC . Thrombosis of the innominate and jugular veins has also been reported [4, 5]. In most cases, PC produces no symptoms and are discovered incidentally on imaging [2, 6]. PC associated with hyperparathyroidism are classified as functioning cysts and are reported to cause hypercalcemic crisis and other stigmata of hypercalcemia [3, 4, 7]. Functioning PC in the setting of multiple endocrine neoplasia type 1 (MEN 1) has also been reported . Although the origin of PC is not fully elucidated, several theories have been proposed to explain their etiology. This includes (1) fluid accumulation within a parathyroid gland, forming a retention cyst, (2) development from a rudimentary fetal complex of gland-like structures derived from parathyroid or thymic tissue (Ku¨rsteiner canals), (3) formation by coalescence of preexisting microcysts, (4) result of cystic degeneration of a parathyroid gland or preexisting adenoma, and (5) formation from the embryologic remnants of the third or fourth branchial cleft . Preoperative diagnosis of PC can be difficult and definitive diagnosis is usually only established after resection. CT, MRI and ultrasonography can all be used to characterize the mass to be cystic while fine-needle aspiration of a clear, watery fluid is suggestive of the diagnosis. Furthermore, analysis of the fluid from the cyst showing a PTH level exceeding that of a simultaneous serum level has been used to confirm the diagnosis of cervical PC [10, 11] and may also be diagnostic in the case of mediastinal PC. All functioning mediastinal PCs, and any non-functioning PC producing local symptoms, should be resected and complete neck exploration considered to exclude other parathyroid gland involvement . Needle aspiration may
be considered definitive therapy for a small, asymptomatic PC since many cervical cysts have been treated successfully in this manner [10, 11]. Historically, sternotomy or thoracotomy has been the preferred approach for resection . However, use of video-assisted thoracoscopic surgery (VATS) has been described, with successful resection of PC as large as 12 cm [2, 4, 8]. To our knowledge, this is the first reported case of PC resection using robot assistance. The main advantage of robotic assistance is the improved visualization provided by the three-dimensional, magnified, highdefinition camera of the robotic system. Given the operating surgeon’s (ZTH) experience with robot-assisted surgery, it was felt that such improved visualization may be helpful given the proximity of the cyst to vital mediastinal structures. Because definitive diagnosis had not been established at the time of surgery, preoperative aspiration of the cyst was necessary to avoid capsular rupture while manipulating the mass and rule out malignancy, which would have mandated a more aggressive, oncologic resection. Our case demonstrates the importance of including PC in the differential diagnosis of a mediastinal cystic lesion. The diagnosis may be established or suspected preoperatively with a cyst fluid PTH that exceeds serum level. All functioning and non-functioning PC causing local symptoms should be resected. Although it is the author’s opinion that use of the robot in the hands of an experienced surgeon is ideal for mediastinal resections, the approach utilized depends on the cyst location, suspicion of malignancy, and surgeon comfort.
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