Which of the following statements are true?

C. The commonest causes of chylothorax are trauma and tumor.

D. The thoracic duct can be ligated with impunity.

DISCUSSION: Chylothorax is most often the result of trauma; however, spontaneous chylothorax is also a manifestation of tumor and should be investigated to identify occult malignancies. Chyle in the thorax is characteristically milky white but can be mistaken for the pseudochylothorax of rheumatoid disease or tuberculosis. If necessary, a diagnosis can be confirmed by lymphangiography. This also facilitates ligation of the thoracic duct, should this become necessary to control the loss of chyle.