Fig. 1

Flow chart and causes of pleural effusions with ADA ≥ 40 IU/L (n = 1134). Data are reported as numbers (%). ^aMesothelioma (n = 9), gastric cancer (n = 9), renal cell carcinoma (n = 8), hepatocellular carcinoma (n = 6), thymic carcinoma (n = 5), breast cancer (n = 4), cholangiocarcinoma (n = 3), pancreas cancer (n = 3), ovary cancer (n = 3), sarcoma (n = 3), thyroid cancer (n = 2), melanoma (n = 1), hypopharynx cancer (n = 1), esophageal cancer (n = 1), colon cancer (n = 1), cervix cancer (n = 1), dysgerminoma (n = 1), ampullary cancer (n = 1), and adenocarcinoma of unknown origin (n = 1). ^bPost-thoracic surgery (n = 24), hemothorax (n = 10), chronic empyema (n = 8), pneumothorax (n = 7), interstitial lung diseases (n = 7), non-tuberculous mycobacterial lung disease (n = 4), chylothorax (n = 3), congestive heart failure (n = 2), pulmonary thromboembolism (n = 1), esophageal perforation (n = 1), and pericarditis (n = 1). ^cPeritonitis (n = 13), liver abscess (n = 5), cholecystitis (n = 3), transcatheter arterial chemoembolization for hepatocellular carcinoma (n = 2), and post-abdominal surgery (n = 1). ^dParasite (n = 6), systemic lupus erythematosus (n = 4), rheumatoid arthritis (n = 3), adult-onset Still’s disease (n = 1), mixed connective tissue disease (n = 1), and hemophagocytic lymphohistiocytosis (n = 1). ADA = adenosine deaminase, MPE = malignant pleural effusion, PPE = parapneumonic effusion, TBP = tuberculous pleurisy