 Introduction/Background Chyle is primarily formed in the intestines and is composed of proteins, lipids, electrolytes, and lymphocytes. A chylous pleural effusion, or chylothorax, is a highly morbid condition defined by the presence of chyle within the pleural respiratory compromise, immunosuppression, malnutrition, and even death [1-3]. A review of the etiology, diagnosis, and management of chylothorax is presented in addition to an evaluation of relevant imaging studies. Etiology Chylothoraces can be categorized etiologically as traumatic or nontraumatic. Collectively, the incidence of chylothorax is approximately 1 per 6000 admissions [1]. Historically, nontraumatic etiologies accounted for up to 72% of cases. Most recently, the largest study reports that traumatic etiologies account for 54% of cases [1,4-7]. The discrepancy may reflect the growth in thoracic oncologic resections or specific referral patterns. Diagnosis Chylothorax most commonly presents with dyspnea, although chest pain, fever, and fatigue may also occur. Chyle is odorless, alkaline, sterile, and milky in appearance, although the appearance may vary based on the nutritional status of the patient. Increasing fatty intake increases the volume and can change the color of the fluid and has been described for the diagnosis of a chyle leak. The hallmark of chylous effusion is the presence of chylomicrons in the fluid. Objective diagnostic criteria include a pleural fluid triglyceride level >110 mg/dL and a ratio of pleural fluid to serum triglyceride level of >1.0. A ratio of pleural fluid to serum cholesterol level of <1.0 distinguishes chylothorax from cholesterol pleural effusions, which may present similarly [2,3]. Management The diagnosis is confirmed by draining the fluid for studies; this is also palliative. After replacing fluid and protein losses, a decision about conservative versus invasive therapies can be made.
Chylothorax Treatment Planning.  Introduction/Background Chyle is primarily formed in the intestines and is composed of proteins, lipids, electrolytes, and lymphocytes. A chylous pleural effusion, or chylothorax, is a highly morbid condition defined by the presence of chyle within the pleural respiratory compromise, immunosuppression, malnutrition, and even death [1-3]. A review of the etiology, diagnosis, and management of chylothorax is presented in addition to an evaluation of relevant imaging studies. Etiology Chylothoraces can be categorized etiologically as traumatic or nontraumatic. Collectively, the incidence of chylothorax is approximately 1 per 6000 admissions [1]. Historically, nontraumatic etiologies accounted for up to 72% of cases. Most recently, the largest study reports that traumatic etiologies account for 54% of cases [1,4-7]. The discrepancy may reflect the growth in thoracic oncologic resections or specific referral patterns. Diagnosis Chylothorax most commonly presents with dyspnea, although chest pain, fever, and fatigue may also occur. Chyle is odorless, alkaline, sterile, and milky in appearance, although the appearance may vary based on the nutritional status of the patient. Increasing fatty intake increases the volume and can change the color of the fluid and has been described for the diagnosis of a chyle leak. The hallmark of chylous effusion is the presence of chylomicrons in the fluid. Objective diagnostic criteria include a pleural fluid triglyceride level >110 mg/dL and a ratio of pleural fluid to serum triglyceride level of >1.0. A ratio of pleural fluid to serum cholesterol level of <1.0 distinguishes chylothorax from cholesterol pleural effusions, which may present similarly [2,3]. Management The diagnosis is confirmed by draining the fluid for studies; this is also palliative. After replacing fluid and protein losses, a decision about conservative versus invasive therapies can be made.