A46-19 Was Invasive Micrometastasis the Culprit? An Unusual Case of Refractory Bilateral Chylothoraces

Abstract Introduction Chylothorax is one of the rare causes of pleural effusion that results from the leak of fat rich lymphatic fluid or chyle into the pleural space. It is mostly traumatic, resulting from iatrogenic injury to the thoracic duct or penetrating trauma, but can also be non-traumatic in the setting of an obstructing malignancy, infectious lymphadenitis, lymphatic flow anomalies. While hematological malignancies are a frequent cause of non-traumatic chylothorax, solid tumors obstructing the thoracic duct or infiltrating lymphatics are a far less common occurrence. Case A 65-year-old gentleman with metastatic esophageal squamous cell cancer presented with several weeks of progressive dyspnea and was hospitalized for acute hypoxic respiratory failure. He had undergone partial esophagectomy with chemoradiation a year before presentation and was on second line chemotherapy due to disease progression with new liver and bony metastases. He required recurrent endoscopic esophageal dilations for dysphagia, the most recent procedure having been performed two months prior. He underwent bilateral thoracenteses revealing transudative effusions, but with elevated triglycerides, consistent with chylothorax. Given rapidly reaccumulating effusions and worsening hypoxia, he underwent right-sided pigtail chest tube insertion and was managed with subcutaneous octreotide and total parenteral nutrition. However, in view of persistent high output chylothorax despite more than two weeks of medical therapy, cancer progression, and ongoing aspiration events, the patient opted for palliative management. He subsequently had bilateral palliative tunneled pleural catheters (TPC) placed and was discharged to home hospice. Discussion Bilateral chylothoraces are rare and have been described in sporadic case reports, most cases being traumatic in origin. Post-radiation fibrosis and thoracic duct injury secondary to esophageal dilation were considered potential etiologies but did not correlate temporally with the disease course. New pleural nodules on updated imaging suggested cancer progression. Although there was no visible compression of the thoracic duct by tumor, a micrometastatic process due to malignant infiltration of lymphatics was considered the likely etiology of the chylothoraces. Managing chylothorax can be challenging and requires a multi-disciplinary approach consisting of dietary fat reduction, pharmacological therapy with somatostatin analogs, and treatment of causative etiology. Persistent high output chylothorax despite optimal medical and dietary management may warrant advanced lymphatic imaging to identify the site of chyle leak for targeted intervention such as thoracic duct embolization or ligation. If the above definitive interventions have failed, or a more conservative approach is favored, refractory chylothorax can be managed via TPC as in this patient. This abstract is funded by: none