Pancreaticopleural Fistula: A Rare Cause of Massive Pleural Effusion

Abstract

Pancreaticopleural fistula (PPF) is a rare sequel of chronic pancreatitis in adults (1–5). We describe a child with idiopathic chronic pancreatitis who presented with a massive pleural effusion caused by PPF. Only two similar cases have been briefly documented previously (6). The pathogenesis, clinical features, and management of this complication of chronic pancreatitis are discussed. CASE REPORT A 4-year-old girl presented to her local Accident and Emergency Department with acute-onset dyspnea. She had been well until 5 months previously, when she began complaining of intermittent, nonspecific abdominal pain. She had subsequently become lethargic and was noted to have loose, pale stools. One month before admission shortness of breath developed and a wheeze that had not responded to treatment with bronchodilators. At presentation she had marked respiratory distress associated with a large right-sided pleural effusion (Fig. 1). Routine hematology and biochemistry test results were normal apart from a mildly elevated white blood cell count (13.3 × 109/L) and a slightly low plasma albumin concentration (35 g/L). A diagnostic pleural tap yielded heavily blood-stained, sterile fluid. Computed tomography of her chest and abdomen confirmed a large right-sided pleural effusion with mediastinal shift, but also revealed a hypodense pancreas containing areas of calcification. Pleural fluid amylase (12,170 IU/L) and plasma amylase (751 IU/L) were both markedly elevated. Further imaging investigations were undertaken to precisely delineate her pancreatic disease. Magnetic resonance cholangiopancreatography (MRCP) showed a dilated, tortuous, irregular pancreatic duct and marked parenchymal atrophy consistent with chronic pancreatitis, together with a pancreatic pseudocyst adjacent to the pancreatic head. Endoscopic retrograde cholangiopancreatography (ERCP) confirmed the ductal abnormalities of chronic pancreatitis without a dominant ductal stricture. It also demonstrated the pseudocyst communicating with the right pleural cavity via a pancreaticopleural fistula (Fig. 2).FIG. 1.: Chest radiograph at presentation showing a large right-sided pleural effusion.FIG. 2.: Endoscopic retrograde cholangiopancreatography demonstrating a posterior pancreatic pseudocyst (C) with a fistula track (F) extending to the right pleural cavity. The pancreatic duct (PD) is dilated, irregular, and tortuous, in keeping with chronic pancreatitis.Initial management was conservative, with chest tube drainage, total parenteral nutrition, and an intravenous infusion of octreotide (1–3 μg/(kg · h)). During the next 2 weeks, there was persistent reaccumulation of pleural fluid and subsequent bacterial infection of the effusion. Surgical treatment was advised, and the patient underwent longitudinal pancreaticojejunostomy: the dilated pancreatic duct, which communicated posteriorly with the pseudocyst and fistula track, was filleted throughout its length and anastomosed to a Roux-en-Y loop of jejunum (7). Postoperatively, the pleural effusion resolved rapidly and completely. Moderately severe pain from chronic pancreatitis required a gradual withdrawal of opioid analgesia and family support from a clinical psychologist. After full enteral feeding was established, steatorrhea and biochemical evidence of pancreatic exocrine insufficiency (low fecal chymotrypsin concentrations) developed, which required treatment with pancreatic enzyme supplements. The patient was also treated with oral antioxidants in an attempt to slow the progress of chronic pancreatitis (8). Eighteen months after surgery, she remains well and pain-free, with a normal growth velocity and no evidence of type 2 diabetes. Results of detailed investigations of the cause of her chronic pancreatitis were all negative; structural pancreatic and biliary anomalies, drug-induced damage, hyperlipidemia, hypercalcemia, organic acidemia, vasculitis, cystic fibrosis (mutation analysis), and α-1-antitrypsin deficiency were specifically excluded. Because the child had been adopted, a detailed family history was not available, but analysis results for cationic trypsinogen gene mutations also proved negative. DISCUSSION Pleuropulmonary complications of pancreatitis are well-described. Small pleural effusions occur in 3% to 17% of patients with acute pancreatitis; these are typically left-sided and arise from chemically mediated inflammation of the diaphragm and pleura (1,6). Pancreatic enzyme concentration in the pleural fluid is at most moderately elevated, and the effusion resolves along with the pancreatitis. In contrast, PPF is characterized by a large pleural effusion rich in amylase and is a rare complication of chronic pancreatitis. Chronic inflammation of the pancreas and obstruction of the main pancreatic duct results in posterior rupture of the duct and the formation of a posterior pseudocyst. Pancreatic fluid leaks into the retroperitoneum and thence to the pleural cavity either via a natural diaphragmatic hiatus or directly through the diaphragm (1,6). The effusion is usually unilateral and serosanguinous but may be bilateral or heavily blood-stained, as it was in our patient. Concomitant pericardial effusions are rare (1). Pancreaticopleural fistula is described as a complication of alcohol-related chronic pancreatitis in adults (1–5). We found only one report of PPF in children. Wakefield et al. (6) described two boys, aged 3 and 4 years, in whom this complication developed. In both boys, the cause of the chronic pancreatitis was unknown. Diagnosis of PPF is often delayed because respiratory symptoms may predominate initially, and the underlying pancreatic disease is frequently asymptomatic (1–6). In some patients, a history of abdominal pain or steatorrhea can be found, but the first clue to pancreatic disease may be the finding of a high pleural fluid amylase concentration. Detailed radiologic imaging is required to confirm the diagnosis. Abdominal ultranography and computed tomography usually show evidence of chronic pancreatitis and may demonstrate a pseudocyst (1,2,4). MRCP, which is noninvasive and does not require additional contrast, has been used to show PPF in adults (4). However, although MRCP revealed the gross disease in our patient, the precise anatomical definition needed for surgery was only delineated by ERCP. ERCP is probably the investigation of choice in small children (6). Initial treatment of the patient with a PPF is aimed at suppressing pancreatic activity to promote resolution of the pleural effusion and closure of the fistula. Experience in adults has shown that chest tube drainage, parenteral nutrition, and somatostatin or octreotide infusion may be successful in up to 40% of cases (1,6). Indications for surgery include persistence of the effusion, bacterial infection of the pseudocyst and/or pleural fluid (which may be fatal), and recurrence of the effusion after reintroduction of oral intake (1,6). A leak from the distal pancreatic duct or a pseudocyst in the tail of the pancreas can be treated by distal pancreatectomy (1). Rarely, a proximal duct stricture can be managed by endoscopic insertion of a pancreatic duct stent (4). Pancreaticojejunostomy is usually required for the more typical proximal duct rupture not responding to medical therapy. The aim of surgery is to achieve free internal drainage of the obstructed pancreatic duct and pseudocyst, allowing resolution of the pleural effusion and spontaneous closure of the fistula. The results of surgery for PPF in adults are good, achieving resolution of the pleural effusion and control of pancreatic symptoms in 80% to 95% of patients (9). Longitudinal pancreaticojejunostomy for symptomatic chronic pancreatitis in children is also associated with a good long-term outcome. DuBay et al. (10) reported on 12 children who were monitored for a median of 15 years after surgery: 8 experienced further episodes of pancreatitis, but symptoms were severe in only 1; 11 were considered to have a good or excellent outcome; nutritional status improved in all, and type 2 diabetes developed in none. In conclusion, PPF is a rare cause of massive pleural effusion. Presenting symptoms are often respiratory and may overshadow any features of chronic pancreatitis. A history of abdominal pain and/or steatorrhea or the radiologic finding of pancreatic calcification should prompt measurement of pleural fluid amylase, which is markedly elevated in PPF. Definitive diagnosis is made by ERCP. If conservative treatment is unsuccessful, then pancreaticojejunostomy should be performed.