Chylothorax is defined as the extravasation of chyle from the thoracic duct or another lymph vessel to the pleural space, due to injury or rupture. The most common cause is traumatic, while most non-traumatic chylothorax is caused by neoplastic disease (mainly lymphoma).1,2

Other causes have been described, including infections, systemic diseases (sarcoidosis, lupus, etc.), jugular vein thrombosis, etc. Central venous thrombosis (CVT) produces increased pressure in the thoracic duct that can cause it to rupture, with leakage of chyle into the pleural cavity. This is a rare event, associated in most cases with thrombotic complications of central venous catheters.3,4 In other cases, CVTs may be due to prothrombotic diseases, such as cancer, inflammatory diseases, and chronic infections.3

The diagnosis of chylothorax is established when the level of triglycerides in pleural fluid is greater than 110mg/dl; values of less than 50mg/dl exclude the diagnosis, while for values between 50 and 110mg/dl, the diagnosis is confirmed by the presence of chylomicrons.4,5

The importance of this disease lies in the fact that chyle is very rich in nutrients (fat, fat-soluble vitamins, proteins) and also contains cells (mainly T lymphocytes). If left untreated, therefore, it can cause immunodeficiency, severe malnutrition, and coagulopathy, etc., and may even be life-threatening.4

We report the case of a 61-year-old man, recipient of a double-lung transplant due to chronic obstructive pulmonary disease (COPD) in April 2017, whose initial progress was satisfactory. Eight months after transplantation, he was admitted to hospital for cytomegalovirus replication in plasma with 5039copies/ml. Skin lesions were also observed on both legs, and had been appearing in outbreaks for the past 2 weeks. Skin punch biopsy was performed, with the following result: “Leukocytoclastic vasculitis. Skin punch showing epidermis with discrete, significant histologic changes. The superficial dermis shows neutrophilic infiltrate surrounding vascular structures associated with endothelial necrosis, extravasation of red blood cells, and karyorrhexis”. Eleven months after surgery, the patient presented a decline in forced expiratory volume in 1 second (FEV1) of 1 liter associated with decreased vesicular breath sounds in the right hemithorax on pulmonary auscultation, so he was admitted for further study. Chest X-ray on admission showed a new right pleural effusion. The study of pleural fluid obtained by thoracentesis found a milky fluid suggestive of chylothorax, so during the same procedure a 20 F chest drain was placed, with collection of 2500ml of liquid. Biochemistry of the fluid showed triglycerides 2462mg/dl. Cervical-chest-abdominal computed tomography (CT) revealed the presence of intraluminal thrombi of acute appearance in the right subclavian vein and left accessory jugular vein, with chronic thrombosis of the left jugular vein.

Standard treatment for chylothorax began, with chest drain, total fasting, complete parenteral nutrition4 and subcutaneous octreotide6–8 for a period of 14 days, in addition to initiating anticoagulation with low molecular weight heparin at a dose of 1mg/kg body weight. Four days after reintroducing an oral fat-free diet, the milky fluid reappeared, so conservative treatment began again for a period of 12 days. It returned again after restarting oral intake, so surgical treatment was indicated.

Surgery consisted of the identification and ligation of the thoracic duct and its accessory branches4 by video-assisted thoracic surgery (VATS). Initial progress was good, but at 48h, a massive right hemothorax developed that required surgical reintervention with polytransfusion of blood products and admission to the post-surgical recovery unit. During the postoperative period, the patient developed acute renal failure that required an adjustment of the dose of tacrolimus. Two weeks after surgery, a clinical picture emerged consistent with acute rejection, so treatment began with corticosteroid boluses of 500mg/12h for 3 days, with satisfactory resolution of the syndrome.

Coinciding with the high-dose corticosteroid treatment, the patient developed a surgical wound infection, which was treated by negative pressure therapy and subsequent surgical closure. There was no relapse of the chylothorax. He was finally discharged in a satisfactory manner.

Thrombosis of the left jugular vein as a cause of chylothorax is an extremely rare entity, according to the literature reviewed.9–11 However, this entity has not previously been reported following lung transplantation.

The most important cause of CVT is related to catheters, but other causes such as systemic diseases have also been described. In our case, the patient did not undergo central venous manipulation. Eight months post-transplantation, he presented cytomegalovirus (CMV) replication in plasma, coinciding with the development of leukocytoclastic vasculitis12 treated with oral prednisone at doses of up to 60mg/day.

In leukocytoclastic vasculitis, vascular injury occurs due to the deposit of circulating immune complexes, which activate the endothelial cells, the fibrinolytic process, and the complement cascade that can lead to intravascular thrombosis.12 Some types of vasculitis, such as Behçet's disease, are known to be related to deep vein thromboses,13,14 so the presence of vasculitis in an immunosuppressed, polymedicated patient could have a role in the pathogenesis of the CVT that caused the chylothorax.

Anticoagulation is the mainstay of treatment for central venous thrombosis, and plays an important role in cases of CVT-related chylothorax when vessel recanalization is achieved.3,15 In our case, anticoagulation was administered, but the expected recanalization was not achieved after one month of conservative treatment, so surgery was performed.

Lung-transplant patients present various complications, such as those described in this case, so rare associations of multiple nosological entities that may be derived from immunosuppression or from infectious states must be ruled out. These patients are extremely complex and pose a diagnostic and therapeutic challenge.