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

## TL;DR

A rare case of bilateral chylothorax is reported, possibly caused by lymphatic reflux into the lungs due to thoracic duct obstruction.

## Contribution

This case highlights a novel mechanism of chylothorax involving retrograde lymphatic flow rather than direct leakage.

## Key findings

- Lymphangiography and CT scans showed contrast accumulation in lung parenchyma and hilar regions, indicating lymphatic reflux.
- Thoracentesis altered chyle distribution, with effusion shifting between sides.
- The case suggests lymphatic reflux may be a cause of idiopathic chylothorax when no secondary cause is found.

## Abstract

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.

We report a rare case of bilateral idiopathic chylothorax that may have resulted from retrograde lymphatic flow into the lungs secondary to thoracic duct obstruction. Lymphangiography and follow‐up CT demonstrated contrast accumulation in the perihilar lymphatic channels and lung parenchyma, supporting the hypothesis of retrograde lymphatic flow rather than direct ductal leakage.