Case Presentation: A 23 year old male presented to the emergency department with left sided pleuritic chest pain radiating to the back, mild cough, clear sputum and shortness of breath for 2 days. He had a history of alcohol abuse related acute pancreatitis one year ago and had another episode of pancreatitis with infected pseudocysts 2 months back. He denied any abdominal pain, nausea, vomiting, fever or chills. Lab work revealed lipase of 190 u/L and amylase of 390 u/l. Chest CT scan showed a new large left-sided pleural effusion, and the pseudocysts surrounding the pancreas had decreased in size when compared to the previous CT scan 2months ago. Thoracentesis was done, draining 1000 cc of brownish-red exudative fluid having an amylase level of 18425 u/L, which revealed the uncommon diagnosis of a pancreatico-pleural fistula (PPF). Magnetic Resonance Cholangiopancreatography (MRCP) was also performed that reported collapsed pancreatic duct with no necrotizing pancreatitis, smaller pseudocysts with a larger collection remaining in the left anterior abdomen and normal biliary structures. A second thoracentesis 2 days later showed a rapidly increasing amylase level of 27380 u/L. Given his ongoing symptoms and recurrent pleural effusions, he was transferred to a pancreatico-biliary center where he was treated with pancreatic stent placement, Percutaneous Endoscopic Gastrostomy (PEG) tube insertion, pleural catheter placement for continued drainage and Endoscopic Ultrasound (EUS) guided cysto-gastrostomy double stents placement. Follow up CT scan of the abdomen showed near resolution of the abdominal fluid collection in the lesser sac and interval decrease in collection size in left upper quadrant.  He was discharged home after a few weeks.

Discussion: Pancreatico-pleural fistula can be rare complication of pseudocysts, which can be very challenging to manage. Use of amylase level in pleural fluid analysis is helpful in making a diagnosis. MRCP is the initial imaging modality of choice to confirm the presence of PPF. Treatment may be conservative but in some cases drainage of the pseudocysts may be required by surgical or endoscopic measures.

Conclusions: Massive pleural effusion in a patient with pancreatic pseudocyst is a rare but serious complication. It may arise from a direct connection between the pseudocyst and the pleural cavity via a PPF. Rarely, this may be the primary presentation of a pseudocyst that can make it a diagnostic challenge leading to management difficulties. We have reported here a rare case of PPF presenting as a large unilateral pleural effusion, managed by endoscopic cysto-gastrostomy which is associated with less morbidity as compared to conventional surgical options.