Abnormal Pulmonary Lymphatic Flow in Patients with Lymphatic Anomalies and Respiratory Compromise.

BACKGROUND: Pulmonary involvement in lymphatic anomalies (LA) is associated with significant morbidity and mortality. Recently described Dynamic Contrast Enhanced Magnetic Resonance lymphangiography (DCMRL) is capable of imaging the lymphatic system in a variety of pulmonary lymphatic disorders.

RESEARCH QUESTION: The objective of this study is to describe the central lymphatic anatomy in patients with LA and pulmonary involvement on DCMRL.

STUDY DESIGN AND METHODS: This prospective observational study enrolled 16 LA patients (mean age 17 years, range 6-63, F/M-9/7) with pulmonary involvement. All patients underwent DCMRL. The lymphatic system was assessed for the presence of mediastinal masses, interstitial lung disease, size and tortuosity of the thoracic duct (TD) and presence of abnormal pulmonary lymphatic flow.

RESULTS: T2 weighted imaging showed: Mediastinal soft tissue masses in 10 patients, diffuse pulmonary interstitial thickening in 13 patients, bone involvement in 15 patients. DCMRL revealed abnormal pulmonary lymphatic flow in 14/16 patients. Abnormal pulmonary lymphatic flow originated from the TD in 3/14, retroperitoneum in 6/14, and both TD and retroperitoneum in 4/14. In 9/16 patients, the TD was dilated and tortuous. In two patients, the TD was not identified and in 5 patients, it was normal.

INTERPRETATION: Abnormal pulmonary lymphatic flow/ perfusion from the TD or retroperitoneum into lung parenchyma occurred in the majority of patients in this study. These findings can explain the interstitial lung disease and chylothorax resulting in deterioration of respiratory function in these patients. Future studies will determine, if mechanical cessation of this abnormal flow can improve pulmonary function and prolong survival in LA patients.