You also don’t see large lymph nodes in the mediastinum or near the hilum or central part of the lung, which are often seen in other types of pneumonia.
In the region of the mediastinum, the trachea divides into two branches called bronchi. Each bronchus leads to a separate lung and divides and subdivides into smaller and finer tubes, somewhat like the branches of a tree.
The most common cause of chylothorax is when the thoracic duct accidently gets damaged during a thoracic surgery, but it can also be caused by tumors in the mediastinum that press up against the thoracic duct and compress it shut.