Chylothorax due to thrombosis of the jugular and subclavian veins in a patient with gastric cancer: a case report

BACKGROUND: Chylothorax is a rare condition due to leakage of chyle in the thoracic cavity. When large amounts of chyle leak into the thoracic cavity, it can lead to severe respiratory, immune, and metabolic complications. Chylothorax has many potential underlying etiologies, and the most common causes are traumatic chylothorax and lymphoma. Venous thrombosis of the upper extremities is a rare cause of a chylothorax. CASE PRESENTATION: A 62-year-old Dutch man with a medical history of gastric cancer, treated with neoadjuvant chemotherapy and surgery 13 months prior, presented with dyspnea and a swollen left arm. Computed tomography thorax showed bilateral pleural effusion that was more prominent on the left side. The computed tomography scan further revealed thrombosis of the left jugular and subclavian veins and osseal masses suggesting cancer metastasis. Thoracentesis was performed to confirm the suspicion of gastric cancer metastasis. The obtained fluid was milky with a high level of triglycerides, but contained no malignant cells; hence, the diagnosis of the pleural effusion was chylothorax. Treatment with anticoagulation and a medium-chain-triglycerides diet was started. Furthermore, bone metastasis was confirmed with a bone biopsy. CONCLUSION: Our case report demonstrates chylothorax as a rare cause of dyspnea in a patient with pleural effusion and a history of cancer. Therefore, this diagnosis should be considered in all patients with a history of cancer with new-onset pleural effusion and thrombosis of the upper extremities or clavicular/mediastinal lymphadenopathy.