Abstract Background Chylothorax, defined as the accumulation of chyle in the pleural space, is a rare form of pleural effusion that results from disruption or obstruction of the thoracic duct. Although iatrogenic injury during surgery is the most frequent cause, non-surgical etiologies such as malignancy account for a significant proportion of cases encountered by pulmonologists in the inpatient setting. Due to the lack of research and standardized treatment protocols, physicians often face challenges in managing this condition. This case series describes the clinical features, management strategies, and outcomes of three patients with malignant chylothorax treated at our institution. Methods We retrospectively analyzed three patients diagnosed with chylothorax secondary to malignancy during 2025 at Loyola University Medical Center. One patient had metastatic renal cell carcinoma and the other two had lymphomas. Diagnosis was confirmed by pleural fluid analysis showing triglyceride levels 110 mg/dL, cholesterol levels 200 mg/dl and a milky appearance. The underlying malignancies included lymphoma in two cases and metastatic renal cell carcinoma in one. Clinical data, management approaches (including dietary modification, pharmacologic therapy, and interventions), and patient outcomes were reviewed. Results All patients presented with progressive dyspnea and large pleural effusions identified on imaging. Two patients had right-sided effusions, and one had a left-sided effusion. Initial management in two patients included thoracentesis, a low-fat, high-protein oral diet emphasizing restriction of long-chain triglycerides (LCTs), and octreotide 200 µg administered subcutaneously three times daily until hospital discharge. Although continuation of octreotide for 14 days was planned, insurance approval could not be obtained. One patient underwent thoracentesis and dietary modification only, declining octreotide therapy. The patient with metastatic renal cell carcinoma experienced recurrent effusions requiring three thoracenteses and an interventional radiology (IR) lymphangiogram. The effusion did not resolve until initiation of a low-fat, high-protein diet combined with octreotide therapy, after which the patient remained free of recurrence. The patients with lymphoma responded favorably to systemic chemotherapy, achieving complete resolution of their chylothoraces. Conclusion Malignant chylothorax remains an uncommon but challenging complication of advanced cancer. Conservative measures, including drainage via thoracentesis, dietary modification, and octreotide, can provide symptomatic benefit, while disease-directed therapy gets started. Larger studies are needed to guide standardized treatment protocols for malignancy-related chylothorax. This abstract is funded by: None
Leuzzi et al. (Fri,) studied this question.