Pancreaticopleural fistula
Pancreaticopleural fistulae are a rare complication of acute or chronic pancreatitis whereby enzymatic pancreatic fluid, either from a pancreatic pseudocyst or directly from a disrupted duct, dissects into the pleural cavity. Pancreaticopleural fistulas may also develop in the setting of trauma or iatrogenic pancreatic duct disruption.
Epidemiology
Pancreaticopleural fistulas are seen in ~5% (range 3-7%) of pancreatitis patients. They most often occur in middle-aged men with a history of chronic alcoholism , although biliary duct obstruction is a more common etiology in children .
It is a rare cause (<1%) of pleural effusion . Fistula-associated pleural effusions are more common on the left side (~75% of cases) .
Clinical presentation
The most common presentation is that of recurrent large pleural effusion in the setting of acute or chronic pancreatitis. Patients classically complain of thoracic symptoms (especially dyspnea) moreso than abdominal pain .
The major described complication is infection of the pleural space and/or lung, resulting from a persistent fistulous communication with the gastrointestinal tract .
Pathology
Due to its enzymatic property, exocrine pancreatic secretions can dissect through fascial planes and communicating into adjacent tissue compartments. For example, dissection anteriorly leads to peritoneal communication, while dissection posteriorly leads to retroperitoneal communication.
Pancreaticopleural fistulas are thought to develop from rupture of a pancreatic collection or pseudocyst into the pleural space either via the aortic/oesophgeal hiatus or through the diaphragmatic muscle itself . Pseudocysts both anterior and posterior to the pancreas can result in pancreaticopleural fistula .
Some fistulas may occur secondary to direct pancreatic duct leak .
Radiographic features
The sensitivity of various imaging modalities to delineate the track is variable :
CT
CT can delineate the fistula track, but moreso depicts changes of pancreatitis. CT shows a hypodense fistulous track from the pancreatic duct, ascending upwards crossing the diaphragm through to the pleural cavity causing pleural effusion.
MRI
MRCP is the imaging modality of choice because it helps to diagnose the presence and site of fistula and to guide further management. Unlike ERCP, it is non-invasive and helps in visualization of the pancreatic duct beyond strictures. Like CT, it can also show changes in pancreatic parenchyma .
Treatment and prognosis
Management of non-healing fistula may require endoscopic or (if necessary) surgical repair. Although endoscopic intervention is often the first-line approach for management, patients may eventually require surgery to address persistent communication.
In general, if the pancreatic duct is normal or mildly dilated and there are no strictures proximal to the site of the leak, pleural drainage (e.g. thoracocentesis) with somatostatin analogs may permit healing and resolution.
Pancreatic duct disruption within the pancreatic head/body with stricture distal to the disruption may be addressed by ERCP-guided stent placement. However, pancreatic duct disruption with obstruction proximal to leak may require pancreatic resection or surgical enteropancreatic anastomosis .
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