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Pancreatitis with or without pseudocyst formation or pancreatic pleural fistula is the most common cause of amylase elevation in pleural fluid. Rupture of the esophagus is the second most common group and malignant effusion is the third.1 Other causes include pancreatic ascites and pancreatic duct trauma. Defect in the wall of the gastrointestinal tract (eg, perforated peptic ulcer) will allow pancreatic secretion to enter the peritoneal cavity. Similarly, peritoneal fluid amylase elevations may be found in the presence of necrotic bowel. Peritoneal fluid, containing such amylase, can find its way into a pleural space.