A 50-year-old man sought treatment in several hospitals because of a severe dry cough. The cough first appeared in December 2020 without obvious inducement, accompanied by a small amount of white foam sputum and sticky sputum. During 1 month, the patient's cough gradually worsened, with dyspnea after activities and paroxysmal dyspnea at night. Cough symptoms were associated with postural changes, such as standing up from sitting, bending over, or turning over during sleep, which could trigger severe coughs, and the patient even had transient amaurosis (self-reported syncope three times). The patient was hospitalized at Xinqiao Hospital of Army Military Medical University (Chongqing, China) on 11 January 2021, and discharged on 21 January 2021. Computed tomography (CT) of the chest showed bilateral pleural effusion (Figure 1A), which was later tested to be chylous fluid (Table 1). The cough was relieved after extracting the pleural fluid. However, the relief could only last for 1 day until the pleural effusion reappeared. The patient had to have pleural effusion extracted every other day to relieve his cough, and the amount of pleural effusion was very large (800-1,000 mL each time). It was suspected that the severe cough was related to recurrent pleural effusion. To determine the cause of such a serious pleural effusion, the patient received enhanced CT, which found an occlusion in the superior vena cava. Because the patient had a long history of dialysis because of uremia, he was recommended to go to the nephrology department to treat his superior vena cava occlusion.
The patient then visited the Department of Nephrology of our hospital. The patient was diagnosed with chronic kidney disease stage 5 in 2003 and received kidney transplantations in 2003 and 2017. The second transplantation failed. He had undergone dialysis for 8 years. In the first 6 months, a right internal jugular vein long-term catheter was used for dialysis, which was later changed to a left brachiocephalic arteriovenous fistula. Physical examination showed that the patient had erythema and edema on the face and neck, diffuse varicosities across the anterior chest, and distended jugular veins. Subsequent CT venography and digital subtraction angiography showed occlusion of the superior vena cava (Figure 1B) and extensive venous collateral vessels within the lower neck and superior mediastinum. The patient was admitted for hospitalization on 20 February 2021. To determine the cause of pleural effusion, 40 mL of pleural fluid was drawn from the right thoracic drainage tube and sent for pleural effusion analysis, exfoliated cell examination (thoracic tumor), and bacterial culture (tuberculosis infection).
The results of the pleural effusion analysis returned on 21st February, showing chyle positivity with elevated lymphocytes (Table 1). No abnormality was found in exfoliated cell examination. Ward rounds showed that the patient's temperature was normal, superficial lymph nodes were not palpable, the breath sounds were low and clear, and no rales were heard. Routine blood tests showed that leukocytes (7.77 x 109/L) and neutrophils (86.5%) were elevated. Because the inflammatory indicators increased in the pleural effusion and blood samples, the patient was given piperacillin-tazobactam (4.5 g q12 h) as treatment. At 1:00 p.m. that day, the patient experienced transient syncope. Sudden loss of consciousness occurred after coughing induced by positional changes from lying to sitting. The patient fell to the ground, without limb twitching, incontinence, or foaming at the mouth. The patient improved spontaneously after 5 s and did not complain of dizziness, headache, palpitations, chest tightness, or dyspnea. His blood pressure was 105/63 mmHg, and his heart rate was 88 times/min. No special treatment was carried out for this syncope.
On 22 February, several tests, including the detection of anti-tuberculosis antibody, sputum smear, sputum culture, and detection of acid-fast bacilli in sputum, were performed. The patient had been taking immunosuppressants since renal transplantation, which might increase the susceptibility to tuberculosis infection. Tuberculosis infection is a possible cause of chylothorax, so we decided to further search for evidence of tuberculosis infection. The bacterial culture of the pleural effusion showed positive results for Staphylococcus lugdunensis, so the antibiotic treatment was continued.
On 23 February, 1,000 mL of effusion was extracted from both lungs through thoracentesis. The pleural fluid analysis showed that the total cell counts decreased, suggesting that the antibiotic treatment was effective. Antibody tests for tuberculosis (gold labeled immunoassay) were weakly positive (+/-), but no Mycobacterium tuberculosis was detected in sputum specimens (sandwich cup method). According to the current examination results, the possibility of tuberculosis infection could be ruled out. Therefore, we speculated that superior vena cava occlusion was the most likely cause of recurrent chylothorax.
On 24th February, percutaneous balloon dilatation was performed to recanalize the superior vena cava (Figure 1C). The superior vena cava was clearly visualized and unobstructed. The collateral circulation mostly disappeared, and the stenosis was relieved.
The patient recovered well in the following days. Physical examination showed that the swelling of the face and neck obviously subsided. Three days after the operation (March 1), the patient received an ultrasound examination for the detection of pleural effusion. The results showed a flaky anechoic area in the bilateral chest, with a maximum depth of 46 mm in the right chest and 40 mm in the left chest. The location of the pleural fluid was not determined due to the small amount. On 3rd March, the patient received a chest CT again. Only a small amount of pleural effusion was found, and most of the lungs were dilated. The patient was discharged on the same day.
Follow-up was conducted after 4 months and 12 months. Chest CT showed no pleural effusion (Figure 1D). The patient reported that cough symptoms were eliminated. Based on the results, we can confirm that the obstruction of the superior vena cava caused the patient to develop recurrent chylothorax, and further stimulated severe postural change-related cough.