Thoracic duct injury is a major complication of neck surgery and involves local and systemic complications, with nutritional and metabolic disorders and immunosuppression which increase operative morbidity and mortality. Around 75% of the lymphatic flow ends through the thoracic duct on the left side of the neck, at the junction of the internal jugular vein and the subclavian vein. Thoracic duct injury is a difficult intraoperative diagnosis because of its low flow output^1,2. Fear of iatrogenic injury should not prevent complete oncologic resection.

We report the case of a 24-year-old woman with a history of total thyroidectomy with right lymph node dissection for papillary thyroid carcinoma. Postoperative staging was T3a N1b M0 with high risk of recurrence. The endocrinologists indicated 150 mCi of I-131, and seven days later a whole-body scintigraphy was ordered. There were four areas of iodine uptake, three in the central region of the neck (surgical bed) and another in the right supraclavicular region, indicating the presence of thyroid tissue. On ultrasound the thyroid space did not present abnormal findings. A heterogeneous lymph node measuring approximately 1.2 cm x 0.6 cm with punctiform hyperechoic images was visualized in the right supraclavicular region. Adjacent to this lesion, there was a hypoechoic fluid-filled lesion measuring approximately 2.6 cm x 1.2 cm which could be related to the history of cancer. The lymph nodes in the left jugulo carotid chain presented diffuse thickening of the cortex with absent fatty hilum; the largest lymph node measured 0.8 x 0.3 centimeters.

Fine needle aspiration (FNA) of the right lateral neck lymph node was performed with measurement of thyroglobulin in the washout fluid. The cytology revealed presence of blood, few mature lymphocytes and thyroglobulin levels of 2.73 ng/mL.

A diagnosis of lymph node recurrence was made, and the patient underwent right neck dissection of level IV and Vb lymph nodes and left neck dissection of levels II, III, IV lymph nodes. A cervical drain was left in the surgical bed. The final diagnosis of the pathology report was metastases from papillary thyroid carcinoma in three right lymph nodes in level IV and in three left lymph nodes in level IV. On postoperative day 2 the patient presented generalized abdominal pain. Laboratory tests and an abdominal ultrasound were ordered. The abdominal ultrasound showed intra-abdominal free fluid, so we decided to perform a contrast-enhanced CT scan of the thorax, abdomen and pelvis. There was abundant free fluid in the peritoneum and retroperitoneum occupying all the regional spaces, with higher density in some sectors. Bilateral moderate pleural effusion (Fig. 1).

Figure 1 Computed tomography scan of the thorax and abdomen: bilateral pleural effusion and free fluid in all the compartments. 

The paracentesis yielded chylous fluid suggestive of inadvertent ligation of the thoracic duct (Fig. 2).

Figure 2 Drainge with chylous output. 

The paracentesis fluid analysis reported cell count 140/mm³, LDH 254 UI/L, glucose 1.13 g/L, milkcolored fluid, amylase 68 UI/L. There was no chylous output from the drain placed in the neck.

Medical treatment was decided: enteral feeding was stopped, and total parenteral feeding was started through a right subclavian catheter; treatment included administration of octreotide and percutaneous drainage. Under ultrasound guidance, a 12-French and a 10-French multipurpose pigtail drainage catheters were placed in the right pleural cavity and in the left iliac fossa, respectively. Chylous fluid was obtained from both drainages. Chylous fluid was obtained from both drainages. During the first days, 600 mL of fluid drained from the thoracic drainage and 150 mL from the abdominal drainage, with progressive decrease in the output until it reached zero 5 days later. Ocreotide was stopped on day 7.

A new CT scan of the neck, thorax, abdomen and pelvis with injection of IV contrast agent was performed on day 10 after medical treatment was started. Scattered air bubbles were observed in the left lateral region of the neck and at the suprasternal level; there was a cutaneous orifice probably secondary to surgery, the thyroid gland was not visualized, and there were no lymph nodes enlarged. Other findings were minimal right pleural effusion with the drain in the basal region and minimal pericardial effusion, absence of left pleural effusion and minimal free abdominal fluid at the level of the pelvis with the drain placed in the left lumbar region.

As the patient had a favorable outcome, oral diet was started with medium-chain triglycerides and the right pleural drain was removed. Parenteral nutrition was stopped under the supervision of the nutrition support service of our institution. The patient was discharged on postoperative day 17 and 13 days after percutaneous drains were placed and medical treatment was started due to the favorable outcome, with indication of follow-up in the outpatient clinic. The abdominal drain was removed 7 days after hospital discharge. During her last visit, the patient was in good general status and was being followed up by the department of endocrinology. Thoracic duct injuries are rare affecting 1-2.5% of head and neck surgery dissections¹. They are more common after thyroidectomies with lymph node dissection², and are more likely to occur in surgical reinterventions, as in our case. The clinical presentation with chylothorax and chyloperitoneum in the setting of these lesions is extremely rare. In our case, the most probable cause is ligation of the thoracic duct in the neck, that is why there was never chylous output through the drainage and producing increased pressure in the cisterna chyli.

The aim of conservative medical treatment of these lesions is to reduce chyle flow, resulting in spontaneous closure of the fistula. This can be achieved by implementing medium-chain triglyceride diet which are absorbed directly into the portal circulation³. Total oral fasting and total parenteral feeding is another option. Somatostatin and octreotide, a somatostatin analog, have different effects in the body, as reducing lymph flow and triglyceride concentration, constituting an important tool in the management of this type of lesions^3-5.

Most authors agree that, if there has been no reduction in the amount of chyle produced after 5 days, patients should return to the operating room for exploration and surgical treatment⁶. Conservative treatment is not recommended in those patients with chylous output > 500 mL/day for 5 consecutive days when, despite treatment, drainage output does not decrease or when there are serious metabolic and nutritional complications; in these cases, surgical treatment is the first choice^5,6.

In conclusion, early diagnosis allows for appropriate medical treatment, which consists of suppressing oral feeding, indicating total parenteral nutrition and somatostatin analogues and follow-up by nutrition specialists. Surgical treatment should not be delayed when this conservative therapy does not achieve good results.