Histiocytic pleural effusion: the strong clue to malignancy

Abstract Background There have been many studies on the clinical characteristics of neutrophilic, lymphocytic, and/or eosinophilic pleural effusion. While caring for patients with effusion, we found that histiocytic effusion (HisPE) was not uncommon. However, few explored HisPE. The purpose present study to determine and etiologies Methods In this retrospective study, HisPE defined as fluid white blood cells comprised ≥ 50% histiocytes. Using a data warehouse, among all aged >18 years who underwent thoracentesis analysis between January 2010 December 2019 at Ulsan University Hospital were enrolled. A total 295 (9.0%) 3279 identified patients. Among them, 201 exudative included. Clinical extracted from medical records analyzed. Results HisPE, major causes malignant ( n = 102 [50.7%]), parapneumonic 9 [4.5%]), tuberculous pleurisy [4.5%]). main types cancer lung 42 [41.2%]), breast 16 [15.7%]), stomach 11 [10.8%]). cancers, adenocarcinoma 34 [81.0%]) most common histology. Conclusions leading cause malignancy, particularly cancer. Physicians should consider possibility disease if histiocytes are predominantly in