A46-45 A Lung Whiteout That Contains a Dark Secret: Chylothorax as the First Manifestation of Lymphoma

Abstract Introduction Chylothorax is a rare phenomenon, accounting for only up to 3% of pleural effusions. These can be broadly classified as traumatic or nontraumatic, with traumatic being most common overall, usually caused by iatrogenic injury during surgery. Malignancy is the most common cause of nontraumatic chylothorax. Lymphoma, predominantly non-Hodgkins’ lymphoma, accounts for up to 70% of cases. We report a case of chylothorax in a patient with newly diagnosed low-grade follicular lymphoma presenting with respiratory and gastrointestinal complaints. Description A 54-year-old male with a history of type 2 diabetes on semaglutide and hypertension presented to the emergency department with progressive dyspnea, post-prandial vomiting, abdominal pain, 60 pounds of weight loss and lower extremity edema. Initial chest x-ray demonstrated a massive left-sided pleural effusion, with a follow-up CT chest with contrast revealing a large, 16.2 x 16.7 cm retroperitoneal mass inseparable from abdominal organs, with left axillary lymphadenopathy. A chest tube was placed with immediate drainage of 2 liters of milky fluid, resulting in relief of respiratory symptoms. Fluid analysis revealed triglycerides of 194 mg/dL and cholesterol of 52 mg/dL, consistent with chylothorax. Flow cytometry of pleural fluid and fine-needle aspiration of the mass demonstrated CD10+ B-cells with Ig-Lambda predominance, confirming a diagnosis of low-grade follicular lymphoma. The patient was started on bendamustine and rituximab while inpatient. Upon removal of the chest tube and initiation of treatment, there was no recurrence of pleural effusion. His hospital course was complicated by tumor lysis syndrome, which was treated, and he was discharged on prophylactic acyclovir and trimethoprim-sulfamethoxazole. Discussion Chylothorax is typically considered a late-stage manifestation of disease. The constellation of symptoms on initial presentation was unique. The patient owed many of his symptoms, including weight loss, abdominal pain and postprandial vomiting to semaglutide. His primary complaint prompting a visit to the emergency department was progressive dyspnea. The large retroperitoneal tumor likely caused a mass effect, leading to gastrointestinal symptoms and possibly thoracic duct obstruction resulting in chylothorax. This condition is typically managed by treating the underlying cause. Prompt drainage resulted in symptomatic relief, and upon diagnosis, he was placed on a low-fat diet, which reduces chyle production. Furthermore, initiation of systemic treatment resulted in no recurrence of fluid accumulation, likely through reduction of tumor size and mass effect. This case highlights chylothorax as a rare initial manifestation of lymphoma and demonstrates the importance of early detection and treatment to ensure complete resolution. This abstract is funded by: None