Bilateral Chylothorax due to Lymphatic Reflux Into the Visceral Pleura From Thoracic Duct Obstruction.

A chylothorax associated with lymphatic reflux is extremely rare. A 77-year-old woman presented with exertional dyspnea. Chest radiography revealed bilateral pleural effusion, and thoracentesis confirmed chyle. Idiopathic chylothorax was diagnosed as no secondary cause was identified. Lymphangiography revealed thoracic duct obstruction cranial to the hilum. A follow-up computed tomography scan showed marked accumulation of contrast material in both the lung parenchyma and hilar regions, a pattern suggestive of lymphatic reflux into the lungs. After left-sided thoracentesis, contralateral pleural effusion decreased, followed by reaccumulation on the left side. These findings indicate an altered chyle distribution after thoracentesis and highlight the role of lymphatic reflux in chylothorax pathogenesis. Recognition of this mechanism may assist diagnosis and guide treatment strategies when no secondary cause can be identified.