The cause of pancreatic hydrothorax most commonly involves which of the following mechanisms?

• A. Pancreatitis or pancreatic pseudocyst rupture
• B. Myocardial infarction
• C. Bacterial pneumonia
• D. Pulmonary embolism

Answer: (A)

Pancreatic hydrothorax arises when pancreatic secretions escape into the pleural space due to disruption of the pancreatic duct or rupture of a pancreatic pseudocyst, creating a fistulous tract into the thorax. In pancreatitis, the duct can rupture and pancreatic fluid tracks through a diaphragmatic defect or via lymphatic channels, most commonly reaching the left pleural space. This transdiaphragmatic leakage brings amylase-rich fluid into the pleural cavity, defining the effusion as pancreatic in origin. Other conditions like myocardial infarction, pneumonia, or pulmonary embolism can cause pleural effusions, but they do not involve leakage of pancreatic enzymes into the pleura.