Left cervical chyloma following right thyroidectomy. (Original Article).

Abstract

Cervical chylomas are rare entities, as only four cases have been previously reported. All of these previous cases involved the left side, all vere related to the thoracic duct, and all occurred following trauma or surgery. We report a new case of a left-sided chyloma that was unusual because it arose following a right-sided subtotal thyroidectomy. The chyloma arose as a left supraclavicular mass within 3 months of the thyroidectomy, and it slowly enlarged over a period of 9 years. Following evaluation by computed tomography, the mass was excised, and the patient recovered uneventfully. We also review what is known about the diagnosis and treatment of cervical chylomas.

Introduction

Only four cases of cervical chylomas have been previously reported in the literature. (1-4) All were left-sided, all were related to the thoracic duct, and all were secondary to trauma or surgery (table). In this article, we describe an unusual case in which a left cervical chyloma developed following a right hemithyroidectomy.

Case report

A 30-year-old woman had undergone a right-sided thyroidectomy for the treatment of benign thyroid disease. Thyroid ultrasound at that time revealed that the patient's right lobe was 5 x 4 x 4 cm and the left lobe was 6 x 1.8 x 1.6 cm. No surrounding adenopathy or mass was noted. The patient recovered from surgery without complication.

Three months postoperatively, the patient noted the onset of left neck swelling in the supraclavicular fossa. A mass was identified and aspirated. Five years later, she experienced a recurrence, and her neck mass measured 12 x 3.8 x 2.2 cm on sonography. No treatment was given at that time. Two years later, the patient reported another neck mass. Computed tomography (CT) identified it as a cystic mass posterior to the sternocleidomastoid muscle. The mass displaced the carotid sheath structures posteromedially. She gradually experienced dysphagia and discomfort in her left neck. The patient declined surgery for the neck mass.

Nine years following her thyroid surgery, a follow-up CT revealed the presence of a 12 x 5-cm cystic mass adjacent to an intact left thyroid lobe (figure 1). Surgical exploration revealed that the mass measured 10 x 8 cm and was located anterior to the inferior jugular vein (figure 2). The cyst was filled with white fluid. No obvious attachment to the thoracic duct was identified, but all attachments and vessels were individually ligated, and the entire mass was excised. An active drain was placed during the immediate postoperative period. This drain was subsequently converted to a passive drain, and a pressure dressing was applied for 1 week. Upon removal of the drain and dressing, no evidence of recurrence was detected. On biochemical analysis, the triglyceride level in the cystic fluid was 4,030 mg/dl and the albumin level was 2.6 g/dl. At the 3-year follow-up, the patient remained chyloma-free, and her symptoms had resolved.

Discussion

In 1565, the thoracic duct was discovered in a horse by Eustachio, an Italian anatomist; this duct was discovered in man by Veslingus in 1634. (1) Until Lampson performed the first successful ligation of the thoracic duct in 1948, surgeons had believed that this procedure would be uniformiy fatal. (1) Since then, however, thoracic duct ligation has been shown to greatly reduce the morbidity and mortality associated with chyle leaks.

Chylomas are rare cystic formations of the thoracic duct or its large tributaries. The thoracic duct drains lymph from most of the body, the exceptions being the right hemithorax, the right upper limb, and the right head and neck. It has been reported to terminate on the left side in 75 to 92% of patients and on the right side in fewer than 5%. (5) The thoracic duct passes behind the great vessels and in front of the branches of the thyrocervical trunk and other vessels that branch off the subclavian artery. It enters the venous system at the junction of the internal jugular vein and subclavian vein, close to the phrenic and vagus nerves. During dissection of these structures, it is possible to damage the thoracic duct. (6) These are the most likely sites of injury during left neck dissections. (7) The thoracic duct is prone to injury during neck dissection because of its tortuous anatomic course and its thin walls.

The right lymphatic duct drains the right side of the head, neck, and chest wall; it also drains the right lung and the lower half of the left lung, the heart, the dome of the liver, and the right diaphragm via the bronchomediastinal trunk. (4) The termination points of these ducts are highly variable, which increases the likelihood of injury to portions of the duct that are located where they would not normally be expected. Aside from the jugulosubclavian junction, the thoracic duct can also terminate in the internal jugular vein, the subclavian vein, and the left brachiocephalic (innominate) vein, and each duct can have multiple termination points into each of these veins. (8)

The thoracic duct has also been known to divide into right and left branches in the upper part of its thoracic course. The left branch courses as previously described, while the right branch terminates into the right subclavian vein with the right lymphatic duct. This is why chylous fistulas can occasionally be seen with right neck dissections. (9 10)

The lymphatic system serves to collect and transport large molecules, such as extravasated plasma proteins, absorbed lipids, and excess tissue fluids that have leaked from the interstitial spaces back into the bloodstream. Chyle, a turbid milky fluid, is made up of lymph fluid and emulsified fat, triglycerides, proteins (mostly albumin), and glucose. The system produces 2 to 4 L of lymph daily.

When the thoracic duct is injured, two complications can arise: chylous leaks and cervical chylomas. Chylous leaks are associated with (1) metabolic derangements secondary to severe fluid, electrolyte, and protein loss, (2) a loss of lymphocytes that results in lymphocytopenia, (3) fistula formation, (4) skin-flap necrosis, and (5) carotid artery blowout. (11 12) The incidence of chyle leaks following neck dissection has been estimated to range from 1 to 5.8%. (5 10) Chylous leaks usually occur during the immediate postoperative period as chylous fistulas or as chylothorax. These leaks occur on the left side secondary to damage to the thoracic duct. They can also occur (1) following trauma, (2) as congenital malformations of lymphatic channels, (3) as a complication of diagnostic procedures, (4) after thoracic surgery, and (5) as a result of a neoplasms. (2 13) Cervical chylomas are a far less common complication. They can cause pain and compressive symptoms on adjacent cervical structures, such as the pleura . (2)

The differential diagnosis of a supraclavicular cystic mass includes a branchial cleft cyst, a cystic hygroma, a thyroglossal duct cyst, a cystic metastatic lesion, a cervical lymphatic cyst, a supraclavicular thoracic duct cyst, a hematoma, a seroma, or a chyloma, (2 13-15)

Establishing the diagnosis of a cervical chyloma requires a determination that the cyst fluid is of chylous origin and that the cyst is in the region of the thoracic duct. All reported cases, including ours, have been associated with either trauma or surgery (table). (1-4) Fluid analysis can be obtained by fine-needle aspiration of the mass. (13) In order to classify a cyst as a chyloma, the fluid analysis should identify an elevated triglyceride level (>100 mg/dl) or an elevated chylomicron level (>4%). Elevation of either of these levels indicates a high likelihood of chybus leakage. CT and ultrasound can help determine the location and extent of the mass. (2) Lymphangiography or lymphoscintigraphy can also be useful in making the diagnosis and in making an intraoperative identification of the mass. (2,14)

Conservative management of a chyloma includes aspiration or drainage of the mass and the application of compressive dressings. Dietary management should include instituting a medium-chain triglyceride diet or delaying the feeding of the patient. Total parenteral nutrition is generally considered to not be beneficial in the management of thoracic duct damage, (16) although some authors have found it to be useful. (5) An agent such as povidone-iodine, a fibrin sealant, or tetracycline can be instilled into the cyst to sclerose the leak. (3,17)

The size of the lesion, a failure of conservative management, and the presence of compressive symptoms are indications for surgical excision of a chyloma. Ligation of the thoracic duct can be accomplished with a minimum of significant morbidity. (18-20)

Our case was interesting because the patient developed a left chyloma even though her initial neck surgery had been performed on the right side. CT revealed that the left side of her thyroid gland was normal, a finding that argued against left neck manipulation as a cause. The chyloma likely occurred secondary to a retraction injury on a portion of her thoracic duct that arched more superomedially than would be expected. Langford et al reported that a thoracic duct can extend as much as 5 cm above the clavicle. (9) The occurrence of a cyst so close to the initial surgery suggests a temporal relationship, but we cannot rule out the possibility that the chyloma arose spontaneously and coincidentally.

Table

Comparison of reported cases of cervical chyloma

                        Age/
Case report             sex   Etiology

O'Neill, 1965 (1)       53/F  Motor vehicle accident
Sinclair et al,         30/F  Motor vehicle accident
 1987 (2)                     with left clavicular
                              fracture
Seelig et al, 1998 (3)  65/F  Left vertebral and
                               subclavian
                              endarterectomy
Miller, 2000 (4)        78/F  Radical neck dissection
Madnani and             30/F  Right thyroidectomy
 Myssiorek, 2003*

                        Definitive
Case report             treatment                Follow-up

O'Neill, 1965 (1)       Thoracic duct ligation   No recurrence at 3 yr
Sinclair et al,         Right thoracotomy with   Not reported
 1987 (2)                thoracic duct ligation

Seelig et al, 1998 (3)  Povidone-iodine          No recurrence at 10 mo
                        irrigation

Miller, 2000 (4)        Dissection and ligation  No recurrence at 6 mo
Madnani and             Dissection and ligation  No recurrence at 3 yr
 Myssiorek, 2003*

* Present report.

References

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(2.) Sinclair D, Woods E, Saibil EA, Taylor GA. "Chyloma": A persistent post-traumatic collection in the left supraclavicular region. J Trauma 1987;27:567-9.

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(8.) Bannister LH, ed. Gray's Anatomy. 38th ed. New York: Churchill Livingstone, 1995:1606-15.

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(13.) Wax MK, Treloar ME. Thoracic duct cyst: An unusual supraclavicular mass. Head Neck 1992;14:502-5.

(14.) Lopez OL, Rodriguez-Maisano E, Delevuax JL. Thoracic duct malformations. Lymphoscintigraphic diagnoses. Clin Nucl Med 1986;11:479-81.

(15.) Myers LL, Pena MT, Sudesh R, et al. Unilocular cervical lymphatic cyst in an adult. Am J Otolaryngol 2000;21:412-15.

(16.) al-Khayat M, Kenyon GS, Fawcett HV, Powell-Tuck J. Nutritional support in patients with low volume chylous fistula following radical neck dissection. J Laryngol Otol 1991;105:1052-6.

(17.) Metson R, Alessi D, Calcaterra TC. Tetracycline sclerotherapy for chylous fistula following neck dissection. Arch Otolaryngol Head Neck Surg 1986;112:651-3.

(18.) Stuart WJ. Operative injuries of the thoracic duct in the neck. Edinborough Med J 1907;22:301-17.

(19.) Loe RM. Injuries of the thoracic duct. Arch Surg 1946;53:448-55.

(20.) Lucente FE, Diktaban T, Lawson W, Biller HF. Chyle fistula management. Otolaryngol Head Neck Surg 1981;89:575-8.

From the Department of Ototaryngology and Communicative Disorders, Long Island Jewish Medical Center, Long Island Campus of the Albert Einstein College of Medicine, New Hyde Park, N.Y.

Reprint requests: David Myssiorek, MD, Long Island Jewish Medical Center, 270-05 76th Ave., New Hyde Park, NY 11040. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

Originally presented at the Eastern Section meeting of the Triological Society; Jan. 25-27, 2002; Philadelphia.