A rare complication: lymphocele following a re-operative right thyroid lobectomy for multinodular goitre

Abstract

Lymphatic leakage is a rare complication of thyroid surgery, the risk of which increases in the presence of malignancy and correlates with the extent of surgery. Although primarily associated with left-sided thoracic duct injuries, lymphatic leaks may occur following right-sided neck dissections for metastatic thyroid cancer. However, the development of a lymphocele following a right-sided lobectomy for benign disease is exceptionally rare. The authors present the case of a patient who developed a cervical lymphocele 10 days after a re-operative right thyroid lobectomy for a multinodular goitre. The patient was successfully managed conservatively with a combination of dietary modification and high-dose octreotide. The reason for her presentation was most likely the result of an occult injury to a congenitally-aberrant lymphatic duct, brought into the operative field by postsurgical adhesions. The case serves to highlight the importance of subtle variations in lymphatic anatomy in the context of a re-operative thyroidectomy.

Background

In the UK, it is estimated that in excess of 10 000 thyroid operations are performed annually.¹ However, despite the proximity of major neurovascular structures, thyroid surgery is associated with a low morbidity and mortality. Significant lymphatic leakage as a consequence of thyroid surgery is infrequent and typically results from damage to the proximal thoracic duct during left-sided neck dissection in the context of thyroid malignancy. However, lymphatic leakage following a right-sided operation for benign disease is a particularly rare event, with only one potential case previously reported.² We present the case of a 58-year-old female patient in whom a lymphocele developed following a right re-operative thyroidectomy for a colloid goitre. This case is of particular importance as it highlights the existence of this complication, serving as a caution to others, and emphasises the benefits of conservative management using a high-dose somatostatin analogue and a specialised diet to resolve this rare condition.

Case presentation

A 58-year-old female of Caucasian descent presented with a right-sided multinodular goitre causing compressive symptoms. Of note, she had previously undergone an uncomplicated left-sided thyroid lobectomy for a colloid goitre 19 years before. The patient had a medical history of asthma, hypothyroidism, essential hypertension and vitamin-D deficiency, but was otherwise well.

The patient elected to undergo surgical management of her goitre and a re-operative right thyroid lobectomy was therefore organised. During the operation, the existing cervicotomy scar was excised and residual scar tissue and adhesions were divided to expose the right thyroid lobe. Macroscopically, the remaining thyroid tissue was noted to be densely nodular with evidence of previous manipulation and adhesions. The operation proceeded without complication and the right recurrent laryngeal nerve and right parathyroid glands were successfully identified and preserved. Postoperatively, the patient was well and was discharged 2 days later. The patient continued to feel well until the 10th postoperative day when she described an unusual sensation in her neck. The following day, she noted an anterior neck swelling at the site of her thyroidectomy (figure 1). The swelling gradually increased in size, but the patient remained apyrexial and systemically well with no dysphagia or airway compromise. The patient sought medical attention and, on arrival in hospital, an abscess was suspected and approximately 50 ml of purulent fluid was aspirated from the neck. The following day, the fluid had re-accumulated and the patient was taken to theatre for a washout of her wound. During the operation, a large volume of what appeared to be pus was washed out with saline and hydrogen peroxide and a vacuum drain was inserted. On the 1st day following her re-operation, the patient’s drain was noted to contain approximately 400 ml of milky fluid. At this point, a lymphatic leak was suspected.

Figure 1.

Appearance of the patient’s neck before surgical drainage (image courtesy of RL Strange).

Investigations

The fluid (figure 2) was sent for biochemical analysis and a significantly raised triglyceride level of 19.53 mmol/l served to confirm its chylous nature. Of note, cultures of the fluid obtained intraoperatively were negative for bacterial growth.

Figure 2.

Gross appearance of the chylous fluid draining from the patient’s neck.

Differential diagnosis

The principle differentials in this case were wound infection with a pyogenic collection, seroma or a delayed haematoma.

Treatment

Following identification of the chyle leak, the patient was commenced on an enteric ultra-low-fat diet and a three times-daily regimen of intramuscular octreotide. The drain output was carefully monitored over the subsequent days; however, it remained at approximately 300 ml per day. Therefore, on the 10th day following her washout, the dose of octreotide was doubled to 200 micrograms three times daily. Following this, the drain output declined sufficiently for the drain to be removed. The patient was discharged 48 h later on a 7-day course of octreotide.

Outcome and follow-up

In the following weeks, the patient went on to make an excellent recovery with no further re-accumulation of chyle (figure 3).

Figure 3.

Appearance of the patient’s neck after discharge from hospital, following her second operation (image courtesy of RL Strange).

Discussion

Lymphatic leakage is a rare, but recognised, complication of thyroid surgery and affects approximately 0.25% of cases.³ However, the incidence rises in patients undergoing thyroidectomy for malignant disease and correlates with the extent of any concomitant neck dissection. In one Korean study, the risk of lymphatic leak following thyroidectomy for malignant disease was 1.8% overall, but the risk rose to 6.2% in those also undergoing bilateral neck dissection.⁴

The diagnosis of a chyle leakage is typically based upon the identification of a triglyceride-rich, milky effluent. A fluid triglyceride level in excess of 100 mg/dl (approximately 5.5 mmol/l) supports the diagnosis of a chylous leak.⁵ In this case, the level was more than three times greater than this value.

Prompt management of lymphatic leakage is of paramount importance in thyroid surgery as, if left unchecked, it may lead to a chylothorax, fluid and electrolyte shifts, or may compromise wound healing.⁶ The management of chyle leaks in the perioperative period has been the focus of several publications; however, the principles of management remain consistent.^{6 7} Ideally, management should involve intraoperative identification and ligation of the damaged lymphatic duct. However, in practice, identification is difficult unless the leak is very large. Furthermore, the situation is often compounded by low lymphatic volumes in patients who have been starved preoperatively.⁷ In the postoperative period, most authors advocate the use of dietary modification to reduce the production of chyle. Enteric regimes typically involve the use of low-fat diets, which may be supplemented by medium-chain fatty acids that are absorbed directly into the portal venous system, bypassing the lymphatics.⁸ Alternatively, total parenteral nutrition may be used to negate any gastrointestinal absorption of fat. Octreotide is also frequently used as an adjunct to conservative therapy as it is thought to reduce intestinal fat absorption and lymph production.⁸ Currently, there appears to be no consensus with regard to dosing; however, in this case, increasing the dose to 200 micrograms three times per day had an apparent beneficial effect in terms of reducing drainage volumes. If a drain is present, there is some evidence that high pressure (−600 mm Hg), as opposed to low pressure, suction drainage is of benefit with regard to reducing the duration of leakage.⁹ Should the conservative approach fail, more invasive therapeutic measures may be employed. These include the injection of sclerosing agents such as tetracycline or OK-432, embolisation or re-operation and formal ligation of the affected lymphatic vessel. For large refractory leaks, there remains the option of thorascopic ligation of the thoracic duct.^{6 7}

Postoperative lymphatic leakage is primarily thought to be the result of injury to the thoracic duct as it loops above the clavicle towards its termination at the junction of the left internal jugular and subclavian veins.¹⁰ Unsurprisingly, the majority of cases to date have followed left-sided thyroid surgery where the thoracic duct is vulnerable, crossing from a medial to lateral position posterior to the left common carotid artery.⁴ However, some studies have noted the occurrence of lymphatic leakage following right-sided surgery. One prospective study found that 8.9% of right-sided neck dissections for metastatic thyroid cancer were complicated by lymphatic leaks.¹¹ It is possible that such occurrences followed injury to the right lymphatic trunk, which typically drains into the right jugulosubclavian angle and may be joined by the right jugular and bronchomediastinal lymphatic trunks. The precise configuration of this structure may also vary. In particular, the right thoracic trunk has been found to empty variously into the right internal jugular or subclavian vein.¹² Furthermore, the right bronchomediastinal trunk may join the right lymphatic trunk from a posterosuperior position,¹² which might result in closer proximity to the thyroid gland. However, the anatomy of this region may be further complicated by the presence of an aberrant thoracic duct. In the developing embryo, there exist paired right and left thoracic ducts; however, only certain portions of this paired system persist to make up the adult thoracic duct. In particular, the distal portion of the right duct and the proximal part of the left duct, joined together by an anastamotic branch, persist into later life. Unsurprisingly, the pattern of persistence of the various parts of the paired thoracic ducts may vary. In some cases, the thoracic duct has been found to divide into right and left branches, with the right branch emptying into the right subclavian or internal jugular vein.^{10 13} Indeed, a recent radiological study found the incidence of a visible right-sided duct to be 4%.¹⁴ A further variation comprises a single right-sided thoracic duct which, in one case, emptied into the right internal jugular vein through three separate terminal branches.¹³

Despite the existence of anatomical anomalies, a right-sided chyle leak following a thyroid lobectomy for benign disease, where no lymphadenectomy has been performed, is extremely unusual. To date, there appears to have been only one previous case described, where a left-sided cervical chyloma appeared after a right thyroid lobectomy for benign disease.² However, the chyloma was only definitively diagnosed 9 years after the original surgery, making aetiological certainty difficult. In the current case, it is possible that the patient’s anatomy was aberrant, bringing a large lymphatic vessel such as a right thoracic duct, bronchomediastinal or right lymphatic trunk into the surgical field. This may have been exacerbated by the presence of multiple adhesions as a consequence of her first thyroid operation. Interestingly, there is some evidence that lymphatic flow and duct size increases in those with cardiac disease, particularly those with mitral valve dysfunction and left ventricular aneurysms.¹² Although there was no history of manifest valvular disease in this case, there is evidence from animal studies that hypertension can increase lymphatic flow.¹⁵ It is therefore conceivable that the delay in the patient’s lymphocele becoming clinically apparent was due to a gradual re-establishment of arterial hypertension as well as re-establishment of a normal, more lipid-rich, diet. Ultimately, this case serves to highlight the potential impact of rare and subtle variations in lymphatic anatomy on common surgical procedures, especially in re-operative cases.

Learning points.

• The thoracic duct may terminate on the right side, with or without prior bifurcation.

• The potential for aberrant lymphatic anatomy and consequent injury must be considered carefully in any cervical operation.

• Conservative management with a combination of dietary modification and a high-dose somatostatin analogue appears to be effective in cervical chyle leaks.