triglyceride over 110 in pleural fluid suggests chylothorax

If you see milky white appearance while doing thoracentesis, you should obtain triglyceride levels to rule out chylothorax.

Chylothorax happens mostly because of thoracic duct obstruction or disruption.

source

Malignancy itself can cause an exudative pleural effusion, but the characteristic "milky white" appearance is typically seen with chylothorax.  Triglycerides >110 mg/dL strongly support the diagnosis.  Chylothorax is a relatively rare cause of pleural effusion, usually due to traumatic or non-traumatic disruption of the thoracic duct.  The most common non-traumatic cause is thoracic duct obstruction due to malignancy, sarcoidosis, or retrosternal goiter, and infections such as tuberculosis and filariasis.  Traumatic disruption most commonly occurs in central venous catheter placement (subclavian approach) and esophageal surgery.  When associated with cirrhosis, congestive heart failure, or nephritic syndrome, the chylothorax may be transudative.