Infectious | Bacterial pneumonia | Tuberculous pleurisy | Parasites | Fungal disease | Viral pneumonias (eg, influenza, coronavirus disease 2019 [COVID-19]) | Nocardia, Actinomyces | Subphrenic abscess | Hepatic abscess | Splenic abscess | Hepatitis | Spontaneous esophageal rupture | Cholecystitis | Iatrogenic or trauma | Central venous catheter misplacement/migration | Drug-induced (eg, nitrofurantoin, dantrolene, methysergide, dasatinib, amiodarone, interleukin-2, procarbazine, methotrexate, clozapine, phenytoin, beta blocker, ergot drugs) | Esophageal perforation | Esophageal sclerotherapy | Enteral feeding tube in pleural space | Radiofrequency ablation of pulmonary neoplasms | Hemothorax | Chylothorax | Malignancy-related | Carcinoma | Lymphoma | Mesothelioma | Leukemia | Chylothorax | Paraproteinemia (multiple myeloma, Waldenstrom's macroglobulinemia) | Paramalignant effusions | Other inflammatory disorders | Pancreatitis (acute, chronic) | Benign asbestos pleural effusion | Pulmonary embolism | Radiation therapy | Uremic pleurisy | Sarcoidosis | Postcardiac injury syndrome | Acute respiratory distress syndrome (ARDS) | Immunoglobulin G4-related disease (fibroinflammatory) | | Increased negative intrapleural pressure with accompanying pleural malignancy or inflammation | Lung entrapment | Cholesterol effusion (eg, due to tuberculosis, rheumatoid arthritis) | Connective tissue disease | Lupus pleuritis | Rheumatoid pleurisy | Mixed connective tissue disease | Eosinophilic granulomatosis with polyangiitis (Churg-Strauss) | Granulomatosis with polyangiitis (Wegener's) | Familial Mediterranean fever | Endocrine dysfunction | Hypothyroidism | Ovarian hyperstimulation syndrome | Lymphatic abnormalities | Malignancy | Chylothorax (eg, yellow nail syndrome, lymphangioleiomyomatosis, lymphangiectasia) | Movement of liquid from abdomen to pleural space | Pancreatitis | Pancreatic pseudocyst | Meigs' syndrome | Chylous ascites | Malignant ascites | Subphrenic abscess | Hepatic abscess (bacterial, amebic) | Splenic abscess, infarction | Miscellaneous | Endometriosis | Drowning | Electrical burns | Capillary leak syndromes | Extramedullary hematopoiesis | |