Ann Thorac Surg 2009;88:2006-2008. doi:10.1016/j.athoracsur.2009.04.138
© 2009 The Society of Thoracic Surgeons
Case Reports
Mediastinal Thoracic Duct Cyst
Keith D. Mortman, MD*
Section of Thoracic Surgery, Washington Hospital Center, Washington, DC
Accepted for publication April 21, 2009.
* Address correspondence to Dr Mortman, Section of Thoracic Surgery, Washington Hospital Center, 110 Irving St, NW, Washington, DC 20010
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Abstract
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Thoracic duct cysts of the mediastinum are rare. This case report describes a 68-year-old woman who was successfully treated with surgical resection. The clinical and radiographic presentation and pathology are discussed, and the pertinent literature is reviewed.
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Introduction
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The differential diagnosis of a mediastinal lesion typically depends on the age of the patient and the location of the mass in the mediastinum. In adults, anterior mediastinal masses account for 65% of mediastinal lesions. Conversely, 52% of mediastinal masses in the pediatric population are found in the posterior mediastinum [1]. Solid neoplasms are most often encountered in each mediastinal compartment. Bronchogenic cysts are the most common mediastinal cystic mass, and these are usually found in the subcarinal or paratracheal regions [2]. Esophageal duplication cysts and neuroenteric cysts are other types of foregut cysts that can be found throughout the mediastinum. Cysts of the thoracic duct can be located anywhere along its course from the cysterna chyli in the abdomen to its insertion with the subclavian and internal jugular veins in the neck. Mediastinal thoracic duct cysts are exceedingly rare, with only a handful of case reports previously published [3, 4]. Herein, a recent case of a mediastinal thoracic duct cyst is reported and the relevant literature is reviewed.
A 68-year-old woman who is a nonsmoker presented with a 3-month history of nonproductive cough, mild dyspnea on exertion, and chest pressure. Aside from a past medical history of gastroesophageal reflux disease, she was healthy. Room air pulse oximetry was 98% and there were no pertinent findings on physical examination. Prior to her referral to our clinic, she was treated for an upper respiratory infection. When antibiotics failed to clear her symptoms, a chest roentgenogram was performed. This revealed a large, retrocardiac mass. A chest computed tomographic scan confirmed the presence of a 6.5-cm low-density retrocardiac lesion (Fig 1). There was no enhancement with intravenous contrast. A transesophageal echocardiogram showed a 6.0 x 6.0 cm well-circumscribed, retrocardiac mass with consolidation and septation but no cardiac compression or invasion. Magnet resonance imaging with gadolinium demonstrated a 5.9 x 6.7 x 7.2 cm mediastinal lesion with mass effect on the inferior vena cava. Note was also made of a distended cysterna chyli (Fig 2). Surgical resection of the mediastinal mass was recommended due to the presence of symptoms and to prevent further growth and compression of adjacent structures. Intraoperative flexible bronchoscopy showed no abnormalities in the airway. Flexible esophagoscopy revealed a small hiatal hernia with Barrett's esophagus, but no other mucosal abnormality to indicate a fistula or communicating cyst. Also, extrinsic compression of the esophagus with leftward deviation was appreciated. A right thoracotomy was performed and the posterior mediastinum was explored. A 7-cm well-circumscribed cyst was found to be arising from the thoracic duct. Afferent and efferent limbs of the thoracic duct were well visualized and were doubly clipped and divided. After removing the mediastinal cyst from the chest (Fig 3), it was opened and found to contain a large amount of brown fluid and brown particulate matter. Histology showed a benign cyst lined by hyalinized fibrous connective tissue surrounded by patchy collections of small lymphocytes (Fig 4). Central hemorrhage with an organizing blood clot was also demonstrated. On the third postoperative day after instituting a regular diet, the patient was noted to have chylous drainage from the chest tube with a triglyceride level of 416 mg/dL and a cell count differential of 83% lymphocytes. After conservative measures failed, the patient was returned to the operating room for exploration on the postoperative day 11. Despite administering heavy cream by mouth preoperatively, an active leak was not identified. The previously placed clips on the thoracic duct were noted to be present and secure. Mass ligation of the tissues between the azygos vein and the aorta at the level of the diaphragmatic hiatus was performed. There were no further complications and she was discharged home on a regular diet 3 days after the second procedure. On follow-up examination 6 months postoperatively, she was noted to be in excellent health with a normal chest roentgenogram and no limitations in her activities.
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Fig 2. Coronal T2-weighted magnetic resonance image showing thoracic duct cyst (short arrow) and distended cysterna chyli (long arrow).
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Fig 4. Histology showing morphologic features of a thoracic duct cyst. (Hematoxylin and eosin stain, x100.)
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Comment
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Cysts of the thoracic duct can occur either above or below the diaphragm. Supradiaphragmatic thoracic duct cysts are typically found in the neck. Mediastinal thoracic duct cysts are quite uncommon. Carbone [5] described the first mediastinal thoracic duct cyst, which was discovered at postmortem examination. The first report of a subdiaphragmatic thoracic duct cyst is credited to Albers in 1836 [6]. Only 32 cases of mediastinal thoracic duct cysts have been reported since Emerson's first antemortem description in a 20-year-old female college student who presented with recurrent attacks of substernal soreness, exertional dyspnea, and a nonproductive cough [6]. Through a posterior mediastinotomy and thoracotomy, he removed a 5.5 x 4.0 cm ovoid, thin-walled cyst arising from the thoracic duct at the level of the seventh vertebral body. The patient was discharged on postoperative day 15. The cause of the thoracic duct cyst is believed to be secondary to a congenital weakness in the wall of the duct, as well as degenerative and lymphangiomatous changes from infection and inflammation [3].
The ages of the patients previously reported ranged from 20 to 86 years, and there is no predominant gender predisposition in these patients. The sizes of the cysts have ranged from 2 to 15 cm with an average of 7 cm. With smaller mediastinal cysts, patients may be asymptomatic. Symptoms from larger mediastinal cysts are usually secondary to compression of adjacent organs. Common symptoms include dyspnea, chest discomfort, nonproductive cough, and dysphagia [7]. These symptoms may be aggravated by food intake.
Bronchogenic and esophageal duplication cysts account for the majority of mediastinal cysts and thoracic duct cysts are rarely believed to be in the differential diagnosis. Magnetic resonance imaging is not routinely required for managing mediastinal cysts but may be able to demonstrate communication of the cyst with the thoracic duct or the cysterna chyli. The high-signal intensity of the T2-weighted images is credited to the high lipid and protein content in the cyst. Percutaneous needle aspiration of the cyst is not mandatory but may confirm the high lipid concentration. As with all mediastinal cysts, however, percutaneous needle aspiration runs the theoretical risk of infecting an otherwise sterile thoracic duct cyst.
Surgical resection of mediastinal cysts, including thoracic duct cysts, is indicated once they are discovered. These cysts are removed to relieve symptoms and to prevent further growth, infection, and possible malignant transformation. The most common postoperative complication is chylothorax. Although chylothorax may respond to conservative measures, it often requires reoperation when it is a complication of surgery. To avoid chylothorax after the resection of a mediastinal thoracic duct cyst, it is critical to ligate both the afferent and efferent limbs of the thoracic duct. Despite this, however, chylothorax may still occur (as in this case). If the original thoracic duct ligatures or clips are clearly demonstrated at reoperation, then mass ligature of the tissues between the aorta and azygos vein at the level of the diaphragmatic hiatus should result in resolution of the chylothorax. Surgical resection is curative and recurrence of a mediastinal thoracic duct cyst has not been reported. In symptomatic patients who are unsuitable for surgical resection, percutaneous or endoscopic aspiration with the injection of a sclerosing agent may be considered.
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References
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- Azanow KS, Pearl RH, Zurcher R, et al. Primary mediastinal masses: a comparison of adult and pediatric populations J Thorac Cardiovasc Surg 1993;106:67-72.[Abstract]
- DeCamp MM, Swanson SJ, Sugarbaker DJ. The mediastinumIn: Baue AE, editor. Glenn's Thoracic and Cardiovascular Surgery. 6th ed.. Stamford, CT: Appleton and Lange; 1996. pp. 654.
- Mattila PS, Tarkkanen J, Mattila S. Thoracic duct cyst: a case report and review of 29 cases Ann Otol Rhinol Laryngol 1999;108:505-508.[Medline]
- Karajiannis A, Krueger T, Stauffer E, Ris HB. Large thoracic duct cyst—a case report and review of the literature Eur J Cardiothorac Surg 2000;17:754-756.[Abstract/Free Full Text]
- Carbone T. Cisti del dotto toracico Gior d Accad Med Torino 1892;40:136-144.
- Emerson GL. Supradiaphragmatic thoracic-duct cyst: an unusual mediastinal tumor New Engl J Med 1950;242:575-578.
- Turkyilmaz A, Eroglu A. A giant thoracic duct cyst: an unusual cause of dysphagia J Thorac Cardiovasc Surg 2007;134:1082-1083.[Free Full Text]
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Abstract
Introduction
