Lymphocyte predominant exudative pleural effusions: a narrative review

Background and Objective: An estimated 1.5 million people develop pleural effusion each year in the United States. Although substantial progress has been made in understanding pleural effusion, establishment of a definite diagnosis usually necessitates thoracentesis with pleural fluid analysis. Lymphocyte predominant pleural effusion is defined as an exudative effusion with lymphocytes over 50% of the total white cell count. The purpose of this review article is to elaborate on the different causes of lymphocyte predominant pleural effusion and the unique biochemical and cellular characteristics of pleural fluid in these conditions. Methods: This review is based on a PubMed search of English-language articles published between 1955 and 2020, using search terms including pleural effusion and lymphocyte predominant to generate a comprehensive literature list that highlights characteristics of pleural fluid in the different conditions associated with lymphocyte predominant pleural effusion. Key Content and Findings: Tuberculosis and malignancy account for the majority of lymphocyte predominant pleural effusions. While less common, a number of conditions such as rheumatoid arthritis, post cardiac injury syndrome, chylothorax, sarcoidosis, yellow-nail syndrome, and uremia have also been described as potential causes of lymphocyte predominant pleural effusions. Conclusion: Once an exudative effusion is identified, cell count and differential can further help narrow the differential diagnosis. Other diagnostic modalities including imaging and thoracoscopy with biopsy can also assist in achieving an accurate diagnosis. Management options include treatment for the underlying cause and/or symptoms, particularly in recurrent malignant pleural effusion.