Answer C. Chyle
Discussion
Her physical examination, chest imaging and pleural fluid studies
were consistent with chylous effusion secondary to SVC syndrome and
anomalous lymphatic drainage.
Chyle is a noninflammatory, alkaline, and bacteriostatic fluid
composed mainly of fat, cholesterol, electrolytes, proteins, glucose,
and abundant lymphocytes. A chylothorax is defined as accumulation of
chyle in the pleural space. 1,2 The thoracic duct transports
between 1.5 and 2.5 L of chyle daily (maximum 4 L/day in a healthy
adult). Flow varies depending on the diet, medications, intestinal
function, and physical activity, and it can increase by two- to 10-fold
for 2 to 3 hours after ingestion of fat, and by 20% after drinking
water.2 Disruption to the thoracic duct may cause improper drainage and development of a chylothorax. 1,2
Complications include malnutrition, respiratory distress, thrombosis,
fluid imbalance, and immunodeficiency (of note, our patient had low
immunoglobulin levels during admission).
The pleural fluid studies revealed elevated triglycerides and
leukocytes which is consistent with chyle and not serous, blood or pus.
There are several causes of chylothorax in infants and children which
vary according to the age of the child or mechanism of injury to the
thoracic duct. It may result from congenital abnormalities of the
lymphatics, which do not always present in the neonatal period.2 Pulmonary lymphangiomas and lymphangiectasia are the 2 major lymphatic abnormalities associated with chylothorax.2 Our patient’s underlying risk factors created the perfect storm for the development of a chylous effusion:
- SVC narrowing from prior cardiac surgeries à elevated venous
pressures in the region into which the thoracic duct drains à increase
pressure within the lymphatic system3
- intrinsic lymphatic abnormality, associated with trisomy 21
- increased lymphatic flow from an acute infection
Following the initial chest tube placement, 300 mL of milky fluid was
removed with improvement in her respiratory status. However,
significant chest tube output persisted despite initiation of total
parenteral nutrition (TPN) for a low fat diet. Ultimately, a SVC stent
was placed after which there was resolution of the chest tube drainage.
The chest tube was pulled and she was discharged home on a low fat diet.
Our patient was treated by Pediatric Hospital Medicine, PICU,
Cardiology, Gastroenterology, Pulmonology, Immunology, Palliative Care,
OT, PT, SLP, Nutrition services and underscores the importance of a
multidisciplinary team approach to these complex diagnoses. At pulmonary
follow up three weeks after her hospitalization, she was doing well
with no change in symptoms or physical examination after transitioning
to a regular diet.
References
-
Tutor, J. D. (2014). "Chylothorax in Infants and Children." Pediatrics 133(4): 722-73
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Solo-Martinez, M., et al. (2009). "Chylothorax: diagnosis and management in Children." Paediatr Respir Rev10(4):199-207
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Nossair, F., et al. (2018). "Pediatric superior vena cava syndrome: An evidence-based systematic review of the literature." Pediatric Blood & Cancer 65(9): e27225
