Abstract Introduction Chylous pleural effusions are uncommon, accounting for 1-3% of all pleural effusions. They are characterized by elevated triglyceride concentrations or the presence of chylomicrons within pleural fluid. Chronic chylothorax can result in significant nutritional loss, electrolyte disturbances, and most importantly immunosuppression due to lymphocyte and immunoglobulin depletion. We present a rare case of chronic chylothorax-associated immunosuppression complicated by Nocardia empyema. Case Presentation A 74-year-old man with COPD on home oxygen and a history of follicular lymphoma in remission since 2019 was admitted multiple times for recurrent pneumonia and bilateral pleural effusions. Thoracenteses performed during each hospitalization yielded an exudative effusion confirming chylothorax. Given concern for lymphoma recurrence, pleural cytology and flow cytometry were obtained but were negative. After discharge, pleural fluid cultures grew Nocardia species and he was readmitted. On readmission, laboratory evaluation demonstrated hypogammaglobulinemia and low CD4+ lymphocyte counts. Imaging revealed bilateral, partially loculated pleural effusions with worsening right-sided ground-glass opacities. MRI of the brain was unremarkable. The patient underwent right-sided chest tube drainage and was started on imipenem-cilastatin and linezolid, with plans to transition to tedizolid for a total of 12 months of therapy per infectious disease recommendations. Discussion Nocardia species are ubiquitous, weakly acid-fast, filamentous bacteria that predominantly infect immunocompromised hosts. Pulmonary nocardiosis is rare, accounting for approximately 6-7 cases per 100,000 hospital admissions, and empyema due to Nocardia has been described only in isolated case reports. This patient possessed multiple predisposing factors, including underlying lung disease, remote lymphoma, and chronic chylothorax. Persistent chylous drainage can lead to the loss of lymphocytes, immunoglobulins, and fat-soluble nutrients, producing a secondary immunodeficiency state that increases susceptibility to opportunistic pathogens such as Nocardia. While there are no previous reports of Nocardia causing chylothorax, it is conceivable that pulmonary nocardiosis in this case may have invaded the thoracic lymphatics, resulting in obstruction and chyle leakage. Nocardia has been shown to disseminate via lymphatic routes, lending biologic plausibility to this mechanism. This case highlights the importance of recognizing chronic chylothorax as a potential cause of secondary immunodeficiency, which may predispose patients to opportunistic infections even in the absence of overt malignancy or immunosuppressive therapy. Conclusion This case represents a rare instance of Nocardia empyema arising in the context of chylothorax-associated immune compromise. Clinicians should maintain a high index of suspicion for opportunistic infections in patients with chronic chyle leaks, particularly when recurrent effusions or atypical organisms are encountered. This abstract is funded by: none
Mubasher et al. (Fri,) studied this question.